Physics Letters B 740 (2015) 83–104 Contents lists available at ScienceDirect Physics Letters B www.elsevier.com/locate/physletb Search for new resonances decaying via WZ to leptons in proton–proton collisions at √ s = 8 TeV .CMS Collaboration � CERN, Switzerland a r t i c l e i n f o a b s t r a c t Article history: Received 13 July 2014 Received in revised form 27 October 2014 Accepted 14 November 2014 Available online 18 November 2014 Editor: M. Doser Keywords: CMS Physics Technicolor A search is performed in proton–proton collisions at √ s = 8 TeV for exotic particles decaying via WZ to fully leptonic final states with electrons, muons, and neutrinos. The data set corresponds to an integrated luminosity of 19.5 fb−1. No significant excess is observed above the expected standard model background. Upper bounds at 95% confidence level are set on the production cross section of a W′ boson as predicted by an extended gauge model, and on the W′WZ coupling. The expected and observed mass limits for a W′ boson, as predicted by this model, are 1.55 and 1.47 TeV, respectively. Stringent limits are also set in the context of low-scale technicolor models under a range of assumptions for the model parameters. © 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/). Funded by SCOAP3. 1. Introduction Many extensions of the standard model (SM) predict heavy charged gauge bosons, generically called W′ , that decay into a WZ boson pair [1–6]. These extensions include models with ex- tended gauge sectors, designed to achieve gauge coupling unifi- cation, and theories with extra spatial dimensions. There are also models in which the W′ couplings to SM fermions are suppressed, giving rise to a fermiophobic W′ with an enhanced coupling to W and Z bosons [7,8]. Further, searches for W′ bosons that de- cay into WZ pairs are complementary to searches in other decay channels [9–19], many of which assume that the W′ → WZ de- cay mode is suppressed. New WZ resonances are also predicted in technicolor models of dynamical electroweak symmetry break- ing [20–22]. This Letter presents a search for exotic particles decaying to a WZ pair with W → �ν and Z → ��, where � is either an elec- tron (e) or a muon (μ), ν denotes a neutrino, and the W and Z bosons are allowed to decay to differently flavored leptons. The data were collected with the CMS experiment in proton–proton collisions at a center-of-mass energy √ s = 8 TeV at the CERN LHC and correspond to an integrated luminosity of 19.5 fb−1. Previous searches in this channel have been performed at the Tevatron [23] and at the LHC [24–26]. The results have typically been interpreted within the context of benchmark models such as an extended gauge model (EGM) [2] and low-scale technicolor (LSTC) mod- � E-mail address: cms-publication-committee-chair@cern.ch. els [21,22]. The search conducted by CMS at √ s = 7 TeV [25] ex- cluded EGM W′ bosons with masses below 1143 GeV and set strin- gent LSTC limits under a range of assumptions regarding model parameters. Complementary searches have also been conducted using the hadronic decays of the W and Z bosons [27–32]. The search at √ s = 8 TeV presented in this paper focuses on the fully leptonic channel, which is characterized by a pair of same-flavor, opposite-charge, isolated leptons with high transverse momentum (pT) and an invariant mass consistent with that of the Z boson. A third, high-pT, isolated, charged lepton is also present, along with missing transverse momentum associated with the neutrino. Background arises from other sources of three charged leptons, both genuine and misidentified. The primary background is the irreducible SM WZ production. Non-resonant events with no genuine Z boson in the final state, such as top quark pair (tt̄), multijet, W + jet, Wγ + jet, and WW + jet production, are also con- sidered. Only the first of these is expected to make a significant contribution. Also included are events with a genuine Z boson de- caying leptonically and a third misidentified or nonisolated lepton, such as Z + jets (including Z +heavy quarks) and Zγ processes. The final background category includes events with a genuine Z boson decaying leptonically and a third genuine isolated lepton, dom- inated by ZZ → 4� decays in which one of the four leptons is undetected. Although irreducible, this contribution is not expected to be significant because of the small ZZ production cross section and dilepton decay branching fraction. The search presented here follows the method applied in the previous analysis [25], whereby a counting experiment is used to compare the number of observed events to the number of http://dx.doi.org/10.1016/j.physletb.2014.11.026 0370-2693/© 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/). Funded by SCOAP3. http://dx.doi.org/10.1016/j.physletb.2014.11.026 http://www.ScienceDirect.com/ http://www.elsevier.com/locate/physletb http://creativecommons.org/licenses/by/3.0/ mailto:cms-publication-committee-chair@cern.ch http://dx.doi.org/10.1016/j.physletb.2014.11.026 http://creativecommons.org/licenses/by/3.0/ http://crossmark.crossref.org/dialog/?doi=10.1016/j.physletb.2014.11.026&domain=pdf 84 CMS Collaboration / Physics Letters B 740 (2015) 83–104 expected signal and background events. However, the new anal- ysis benefits from the increase in center-of-mass energy to 8 TeV and also from improvements in lepton identification, particularly at high pT. An increase in sensitivity is achieved at high W′ masses by using optimized isolation criteria that successfully take into account collimated leptons from highly boosted Z bosons. The larger center-of-mass energy alone increases the signal pro- duction cross section by roughly 45–70% for W′ masses between 1000–1500 GeV, while the improved lepton isolation criteria con- tribute a 50% increase in signal efficiency over the same range. Additional improvements related to the optimization of selection criteria are also incorporated. Finally, as in the previous anal- ysis [25], the results are interpreted within the context of W′ bosons in extended gauge models and vector particles in LSTC models. 2. The CMS detector The central feature of the CMS apparatus is a superconduct- ing solenoid of 6 m internal diameter, providing a magnetic field of 3.8 T. Within the superconducting solenoid volume are a sili- con pixel and strip tracker, a lead tungstate crystal electromagnetic calorimeter (ECAL), and a brass and scintillator hadron calorime- ter (HCAL), each composed of a barrel and two endcap sections. Muons are measured in gas-ionization detectors embedded in the steel flux-return yoke outside the solenoid. Extensive forward calorimetry complements the coverage provided by the barrel and endcap detectors. The ECAL energy resolution for electrons with transverse energy ET ≈ 45 GeV from Z → ee decays is better than 2% in the central region of the ECAL barrel (|η| < 0.8), and is between 2% and 5% elsewhere. For low-bremsstrahlung electrons, where 94% or more of their energy is contained within a 3 × 3 array of crystals, the energy resolution improves to 1.5% for |η| < 0.8 [33]. Muons are measured in the pseudorapidity range |η| < 2.4, with detection planes made using three technologies: drift tubes, cathode strip chambers, and resistive-plate chambers. Matching muons to tracks measured in the silicon tracker results in a pT resolution between 1 and 5%, for pT values up to 1 TeV [34]. The particle-flow method [35,36] consists in reconstructing and identifying each single particle with an optimized combination of all subdetector information. The energy of photons is directly ob- tained from the ECAL measurement, corrected for zero-suppression effects. The energy of electrons is determined from a combi- nation of the track momentum at the main interaction vertex, the corresponding ECAL cluster energy, and the energy sum of all bremsstrahlung photons attached to the track. The energy of muons is obtained from the corresponding track momentum. A more detailed description of the CMS detector, together with a definition of the coordinate system used and the relevant kine- matic variables, can be found elsewhere [37]. 3. Event simulation The pythia 6.426 event generator [38] and the CTEQ6L1 [39] parton distribution functions (PDFs) were used for producing the EGM W′ and LSTC signal samples. For the detailed simulation of the W′ samples, pythia was used for parton showering and hadronization with the Z2* tune [40] for the underlying event simulation. Cross sections are scaled to next-to-next-to-leading or- der (NNLO) values calculated with fewz 2.0 [41], and range from 27.96 fb to 0.33 fb for W′ masses between 1000 and 1500 GeV. Characteristic signal widths are between 100 and 168 GeV for the same mass range and are dominated by the detector resolution, since the natural widths vary from 33 to 54 GeV. For the LSTC study we assume that the technihadrons ρTC and aTC decay to WZ. Since these two states are expected to be nearly mass-degenerate [22], they would appear as a single fea- ture in the WZ invariant mass spectrum, and we hereafter refer to them collectively as ρTC. Since we do not expect a difference in the kinematics between the W′ and LSTC signals, we use the W′ samples as the default for the analysis, with the cross sections for LSTC as given by pythia. We consider the same relationship between the masses of the ρTC and πTC technihadrons as used in Refs. [25] and [42], MπTC = 3 4 MρTC − 25 GeV, and also investi- gate the dependence of the results on the relative values of the ρTC and πTC masses. The relationship between the masses signif- icantly affects the ρTC branching fractions [42]. If MρTC < 2MπTC , the decay ρTC → WπTC dominates, such that the branching frac- tion B(ρTC → WZ) < 10%. However, if the ρTC → WπTC decay is kinematically inaccessible, B(ρTC → WZ) approaches 100%. Follow- ing Ref. [42] we also assume that the LSTC parameter sin χ is equal to 1/3. Changes in this parameter affect the branching fractions for decay into WZ and WπTC. The MadGraph 5.1 [43] and powheg 1.1 [44–47] generators are interfaced to pythia for parton showering, hadronization, and sim- ulation of the underlying event. The SM WZ process, which is the dominant irreducible background, was generated with MadGraph. The ZZ process, which contributes when one of the leptons is either outside the detector acceptance or misreconstructed, was generated using powheg. The instrumental backgrounds were pro- duced using MadGraph and include Z + jets, tt̄, Zγ , WW + jets, and W + jets. The background contribution from QCD multijet events and from Wγ events was also studied in the simulation and found to be negligible. Next-to-leading order (NLO) cross sections are used with the exception of the W + jets process, where the NNLO cross section is used. The W′ signal and SM processes used to estimate background were modeled using a full Geant4 [48] sim- ulation of the CMS detector. For all the simulated samples, the additional proton–proton in- teractions in each beam crossing (pileup) were modeled by super- imposing minimum bias interactions (obtained using pythia with the Z2* tune) onto simulated events, with the multiplicity distri- bution matching the one observed in data. 4. Object reconstruction and event selection The WZ → 3�ν decay is characterized by a pair of same- flavor, opposite-charge, high-pT isolated leptons with an invariant mass consistent with a Z boson, a third, high-pT isolated lep- ton, and a significant amount of missing transverse momentum associated with the escaping neutrino. The analysis, therefore, re- lies on the reconstruction of three types of objects: electrons, muons, and Emiss T . The magnitude of the negative vector sum of transverse momenta of all reconstructed candidates is used to cal- culate Emiss T . The events are reconstructed using a particle-flow approach [35,36] and the details of the selection are provided be- low. Candidate events are required to have at least three recon- structed leptons (e, μ) within the chosen detector acceptance of |η| < 2.5 (2.4) for electrons (muons). The events are selected on- line using a double-electron or double-muon trigger for final states with the Z boson decaying into electrons or muons, respectively. The double-electron trigger requires two clusters in the ECAL with ET > 33 GeV. The lateral spread in η of the energy de- posits comprising the cluster is required to be compatible with that of an electron. The trigger also requires that the sum of the energy detected in the HCAL in a cone of R < 0.14, where R = √ ( φ)2 + ( η)2, centered on the cluster, be no more than 15% (10%) of the cluster energy in the barrel (endcap) region of the CMS Collaboration / Physics Letters B 740 (2015) 83–104 85 ECAL. Finally, the clusters are matched in η and φ to a track that includes hits in the pixel detector. The double-muon trigger requires a global muon with pT > 22 GeV and a tracker muon with pT > 8 GeV. The global muon is reconstructed using an outside-in approach whereby each muon candidate in the muon system is matched to a track reconstructed in the tracker and a global fit combining tracker and muon hits is performed [34]. The tracker muon is reconstructed using an inside- out approach in which all tracks that are considered as possible muon candidates are extrapolated out to the muon system. If at least one muon segment matches the extrapolated track, it quali- fies as a tracker muon. The trigger requirements described above have been changed from those in Ref. [25] wherein two global muons were required to pass the online selection. The new re- quirements improve sensitivity for collimated muons from highly boosted Z bosons. Simulated events are weighted according to trigger efficiencies measured, in both observed and simulated data, using the “tag- and-probe” technique [49] with a large Z → �� sample. In the electron channel, we apply a parametrization based on the turn-on curve measured with observed electrons and find trigger efficien- cies to be above 99%. Muon trigger efficiencies above the turn-on are typically measured to be above 90% in observed events. Scale factors are also applied to the simulated samples to account for differences between the observed and simulated trigger efficien- cies. These are approximately unity for both the electron and muon channels. Candidates for leptons from the W and Z boson decays are also required to pass a series of identification and isolation crite- ria designed to reduce background from jets that are misidentified as leptons. Electron candidates are reconstructed from a collec- tion of electromagnetic clusters with matched tracks. The electron momentum is obtained from a fit to the electron track using a Gaussian-sum filter algorithm [50] along its trajectory taking into account the possible emission of bremsstrahlung photons in the silicon tracker. We require pT > 35 (20) GeV for the electrons from the Z (W) boson decay. We also require |η| < 2.5 and exclude the barrel and endcap transition region (1.444 < |η| < 1.566) as electron reconstruction in this region is not optimal. In compari- son with the requirements imposed on electrons from the W bo- son decays, a looser set of identification requirements, primarily based on the spatial matching between the track and the electro- magnetic cluster, is imposed for the electrons from the Z boson decays. Electron candidates are also required to be isolated with particle-flow-based relative isolation, Irel , less than 0.15, where Irel is defined as the sum of the transverse momenta of all neutral and charged reconstructed particle-flow candidates inside a cone of R < 0.3 around the electron in η–φ space divided by the pT of the electron. The Irel computation includes an event-by-event correction applied to account for the effect of pileup [51]. Finally, if an electromagnetic cluster associated with a photon from inter- nal bremsstrahlung in W and Z boson decays happens to be closely aligned with a muon track, it may be misreconstructed as an elec- tron. In order to remove such instances of misreconstruction, elec- trons are rejected if they are within a cone of R < 0.01 around a muon. Observed-to-simulated scale factors for these identifi- cation and isolation requirements, measured using tag-and-probe and parametrized as a function of electron pT and |η|, are applied as corrections to the simulated samples. Global muon candidates are reconstructed using information from both the silicon tracker and the muon system. Candidates are required to have at least one muon chamber hit that is included in the global muon track fit and at least two matched segments in the muon system. We require muons with |η| < 2.4 and leading (sub- leading) muon pT > 25 (10) GeV for the muons from the Z decay and pT > 20 GeV for the muons from the W decay. We also require δpT/pT < 0.3 for the track used for the momentum determination, where δpT is the uncertainty on the measured transverse momen- tum, and we eliminate cosmic ray background by requiring that the transverse impact parameter of the muon with respect to the primary vertex position be less than 2 mm. Particle-flow-based relative isolation, with pileup corrections applied [52], is defined using a cone of size R < 0.4 around the primary muon and is required to be less than 0.12. The above identification criteria are modified for muons coming from the Z boson decay: one of the muons is allowed to be a tracker muon only and the requirement on the number of muon chamber hits is removed. Additionally, the isolation variable for each muon is modified to remove the contribution of the other muon. These modifications improve the signal efficiency and hence the overall sensitivity for high-mass W′ bosons. Simulated samples are corrected using observed-to- simulated scale factors that are parametrized as a function of muon |η|. Opposite-sign, same-flavor lepton pairs with invariant mass be- tween 71 and 111 GeV, consistent with the Z boson mass, are used to reconstruct Z boson candidates. In the case of more than one Z boson candidate, where the two candidates share a lepton, the candidate with the mass closest to the nominal Z boson mass [7] is selected. Events with two distinct Z boson candidates, where the candidates do not share a lepton, are rejected in order to suppress the ZZ background. The charge misidentification rate for the lep- tons considered in the analysis is very small and thus neglected. A candidate for the charged lepton from the decay of a W bo- son, in the following referred to as a W lepton, is then selected out of the remaining leptons. When several candidates are found, the one with the highest pT is selected. Neutrinos from the leptonic W boson decays escape from the detector without registering a signal and result in significant Emiss T in the event. In order to in- crease the purity of the selection of W boson decays, the Emiss T in the event is required to be larger than 30 GeV. This requirement discriminates against both high-pT jets misidentified as leptons and photon conversions, where the source of the misidentified jet or photon can come from Z + jets or Zγ events, respectively. In order to suppress events where final-state radiation produces additional leptons (via photon conversion) that are identified as the W lepton, we apply two additional requirements on the event after the W lepton selection. First, events with the trilepton invari- ant mass m3� < 120 GeV are rejected to remove events where m3� is close to the Z boson mass. Second, events where the R be- tween either lepton from the Z boson decay and the W lepton is less than 0.3 are rejected. This removes cases where the W lepton candidate comes from a converted photon and is unlikely to occur in the boosted topology of a massive W′ boson decay. After the W and Z candidate selection, the two bosons are combined into a WZ candidate. The invariant mass of this can- didate cannot be determined uniquely since the longitudinal mo- mentum of the neutrino is unknown. We follow the procedure used in the previous CMS analysis [25] and assume the W bo- son to have its nominal mass, thereby constraining the value of the neutrino longitudinal momentum to one of the two solutions of a quadratic equation. Detector resolution effects can result in a reconstructed transverse mass larger than the invariant W boson mass, MW, leading to complex solutions for the neutrino longitu- dinal momentum. In these cases, a real solution is recovered by setting MW equal to the measured transverse mass. This results in two identical solutions for the neutrino longitudinal momentum. In simulated events with two distinct, real solutions, the smaller- magnitude solution was found to be correct in approximately 70% of the cases, and this solution was therefore chosen for all such events. Fig. 1 (top) shows the WZ invariant mass distributions, 86 CMS Collaboration / Physics Letters B 740 (2015) 83–104 Fig. 1. The WZ invariant mass (top) and LT (bottom) distributions for the back- ground, signal, and observed events after the WZ candidate selection. The last bin includes overflow events. The (obs − bkg)/σ in the lower panel is defined as the difference between the number of observed events and the number of expected background events divided by the total statistical uncertainty. after the WZ-candidate selection, for signal, background, and ob- served events. At this point, the irreducible WZ process dominates the background contribution, making up ∼85% of the total number of expected background events. In order to further suppress SM background events, we apply two additional selection requirements. The first is a requirement on LT, the scalar sum of the charged leptons’ transverse momenta, shown in Fig. 1 (bottom). The second is a requirement on the mass of the WZ system. The thresholds for these selection crite- ria are varied simultaneously at 100 GeV mass spacing for the WZ invariant mass and optimized for the best expected limit on the W′ production. These optimal values are then plotted as a func- tion of the WZ mass and an analytic function is fit to the result- ing distribution. For the mass-window requirement, two regimes of linear behavior are observed: for masses less than 1200 GeV, a narrow mass window is optimal in order to reject as much background as possible. Above 1200 GeV, the background ceases to contribute significantly and it is better to have a large mass window. The LT requirement exhibits a linear relationship: as the mass increases, it is optimal to require a larger LT, until around 1000 GeV, at which point having LT greater than 500 GeV is suf- ficient. These mass windows and LT requirements are summarized in Table 1. 5. Systematic uncertainties Systematic uncertainties affecting the analysis can be grouped into four categories. In the first group we include uncertainties that are determined from simulation. These include uncertainties in the lepton and Emiss T energy scales and resolution, as well as uncertain- ties in the PDFs. Following the recommendations of the PDF4LHC group [53,54], PDF and αs variations of the MSTW2008 [55], CT10 [56], and NNPDF2.0 [57] PDF sets are taken into account and their impact on the WZ cross section estimated. Signal PDF un- certainties are taken into account only to derive uncertainty bands around the signal cross sections, as shown in Fig. 2, and do not impact the central limit. An uncertainty associated with the simu- lation of pileup is also taken into account. The second group includes the systematic uncertainties affect- ing the observed-to-simulated scale factors for the efficiencies of the trigger, reconstruction, and identification requirements. These efficiencies are derived from tag-and-probe studies, and the un- certainty in the ratio of the efficiencies is typically taken as the systematic uncertainty. For the Z → ee channel, we assign a 2% un- certainty related to the trigger scale factors, another 2% to account for the difference between the observed and simulated reconstruc- tion efficiencies, and an additional 1% uncertainty related to the electron identification and isolation scale factors. For the Z → μμ channel, we assign a 5% uncertainty related to the trigger and an- other 2% uncertainty due to the differences in the observed and simulated efficiencies of muon reconstruction. An additional 3% uncertainty is assigned to the muon identification and isolation scale factors to cover potential differences related to the boosted topology of the signal. The third category comprises uncertainties in the background yield. These are dominated by the theoretical uncertainties associ- ated with the WZ background. We consider contributions coming from uncertainties related to the choice of PDF (described above), renormalization and factorization scales, and the SM WZ produc- tion modeling in MadGraph. Scale uncertainties were determined by studying the variation of the cross section in the same phase space of the analysis by varying the renormalization and factor- ization scales by a factor of two upwards and downwards with respect to their nominal values. The largest observed variation is taken as a systematic uncertainty. This procedure results in uncer- tainties of 5% for WZ masses up to 500 GeV and up to 15% from 600 GeV to 2 TeV. As the MadGraph sample used for simulating the WZ background contains explicit production of additional jets at matrix-element level, it provides a reasonable description of the process. The prediction is thus only rescaled with a global factor to the total NLO cross section computed with mcfm 6.6 [58]. To estimate uncertainties related to remaining modeling differences between the spectra predicted by MadGraph and true NLO predic- tions, we studied the ratio of the WZ cross section in the phase space defined by the analysis selection criteria (for each mass point) to the inclusive WZ cross section. We compared this ratio between MadGraph and mcfm and found differences of the order of 5% for WZ masses up to 1 TeV, and of the order of 30% between 1 and 2 TeV. These differences are taken as additional systematic uncertainties in the SM WZ background. For other background pro- cesses, the cross sections are varied by amounts estimated for the phase space relevant for this analysis as follows: ZZ and Z + jets by 30%, tt̄ by 15%, and Zγ by 50%. CMS Collaboration / Physics Letters B 740 (2015) 83–104 87 Table 1 Minimum LT requirements and search windows for each EGM W′ mass point along with the number of expected background events (Nbkg), observed events (Nobs), expected W′ signal events (Nsig), and the product of the signal efficiency and acceptance (εsig × Acc.). The indicated uncertainties are statistical only. W′ mass (GeV) LT (GeV) MWZ window (GeV) Nbkg Nobs Nsig εsig × Acc. (%) 170 110 163–177 9.0±0.3 8 18±1 1.33 ±0.09 180 115 172–188 38 ±2 49 140 ±7 1.97 ±0.09 190 120 181–199 62 ±1 76 371 ±14 2.6±0.1 200 125 190–210 81 ±4 86 610 ±20 3.2±0.1 210 130 199–221 86 ±3 101 786 ±23 3.9±0.1 220 135 208–232 91 ±3 84 896 ±24 4.5±0.1 230 140 217–243 92 ±4 80 977 ±25 5.2±0.1 240 145 226–254 91 ±4 84 1011 ±24 5.8±0.1 250 150 235–265 82 ±1 85 1021 ±23 6.4±0.1 275 162 258–292 73 ±3 85 970 ±20 8.0 ±0.2 300 175 280–320 60 ±1 74 858 ±16 9.6±0.2 325 188 302–348 56 ±3 53 792 ±13 11.8 ±0.2 350 200 325–375 48 ±3 37 699 ±10 13.9 ±0.2 400 225 370–430 32 ±1 40 542 ±7 18.1 ±0.2 450 250 415–485 23.1±0.8 26 399 ±5 21.5 ±0.2 500 275 460–540 16.6±0.5 13 297 ±3 24.8 ±0.3 550 300 505–595 13.2±0.6 14 220 ±2 27.6 ±0.3 600 325 550–650 10.0±0.5 10 167 ±2 30.4±0.3 700 375 640–760 4.7±0.2 4 96.9 ±0.8 34.3 ±0.3 800 425 730–870 2.8±0.2 5 56.5 ±0.5 36.5 ±0.3 900 475 820–980 2.1±0.2 4 35.0 ±0.3 38.6 ±0.3 1000 500 910–1090 1.4±0.1 0 23.7 ±0.2 43.3 ±0.3 1100 500 1000–1200 0.8±0.1 0 15.9 ±0.1 46.8 ±0.3 1200 500 1080–1320 0.58±0.08 1 10.77±0.07 49.1 ±0.3 1300 500 1108–1492 0.56±0.08 1 8.20 ±0.04 56.1 ±0.3 1400 500 1135–1665 0.60±0.08 1 5.64 ±0.03 57.3 ±0.3 1500 500 1162–1838 0.57±0.08 1 3.76 ±0.02 57.5 ±0.3 1600 500 1190–2010 0.56±0.08 1 2.56 ±0.01 57.7 ±0.3 1700 500 1218–2182 0.50±0.08 1 1.782 ±0.009 57.6 ±0.3 1800 500 1245–2355 0.44±0.07 1 1.255 ±0.007 58.0 ±0.3 1900 500 1272–2528 0.39±0.07 0 0.844±0.005 55.0 ±0.3 2000 500 1300–2700 0.36±0.07 0 0.595±0.003 54.7 ±0.3 Fig. 2. Limits at 95% CL on σ × B(W′ → 3�ν) as a function of the mass of the EGM W′ (blue) and ρTC (red), along with the 1σ and 2σ combined statisti- cal and systematic uncertainties indicated by the green (dark) and yellow (light) bands, respectively. The theoretical cross sections include a mass-dependent NNLO K-factor. The thickness of the theory lines represents the PDF uncertainty associ- ated with the signal cross sections. The predicted cross sections for ρTC assume that MπTC = 3 4 MρTC − 25 GeV and that the LSTC parameter sinχ = 1/3. (For inter- pretation of the references to color in this figure legend, the reader is referred to the web version of this article.) Finally, an additional uncertainty of 2.6% due to the measure- ment of the integrated luminosity is included [59]. Table 2 presents a summary of the above systematic uncertainties. Table 2 Summary of systematic uncertainties. Values are given for the impact on signal and background event yields. When the value of the uncertainty differs between the different decay modes of the W and Z bosons and/or between different W′ masses considered, a range is quoted in order to provide an idea of the magnitude of the uncertainty, i.e. its impact. Systematic uncertainty Signal impact Background impact Emiss T resolution & scale 1–3% 1–23% Muon pT resolution 1–3% 0.5–5% Muon pT scale 1–2% 1–22% Electron energy scale & resolution 0.5–2% 1.5–12% Pileup 0.1–0.8% 0.5–5% Electron trigger efficiency 2% 2% Electron reconstruction efficiency 2% 2% Electron ID & isolation efficiencies 1% 1% Muon trigger efficiency 5% 5% Muon reconstruction efficiency 2% 2% Muon ID & isolation efficiencies 3% 3% Z + jets – 30% tt̄ – 15% Zγ – 50% ZZ – 30% WZ PDF – 5–10% WZ scale – 5–15% WZ MadGraph modeling – 5–30% Luminosity 2.6% 2.6% 6. Results As shown in Fig. 1, the data are compatible with the ex- pected SM background and no significant excess is observed. Ex- clusion limits on the production cross section σ(pp → W′/ρTC → WZ) ×B(WZ → 3�ν) are determined using a counting experiment and comparing the number of observed events to the number of 88 CMS Collaboration / Physics Letters B 740 (2015) 83–104 Fig. 3. Two-dimensional exclusion limit at 95% CL for the LSTC model as a function of the ρTC and πTC masses. expected signal and background events. The limits are calculated at 95% confidence level (CL) by employing the RooStats [60] im- plementation of Bayesian statistics [7] and assuming a flat prior for the signal production cross section. Systematic uncertainties, other than signal PDF uncertainties, are represented by nuisance parameters. The results for the number of observed and expected background and signal events at different W′ masses, along with the efficiency times acceptance, are given in Table 1. The expected (observed) lower limit on the mass of the W′ boson is 1.55 (1.47) TeV in the EGM. For LSTC, with the chosen parameters MπTC = 3 4 MρTC − 25 GeV, the expected and observed ρTC mass limits are 1.09 and 1.14 TeV, respectively. For each of the above cases the lower bound on the exclusion limit is 0.17 TeV. Fig. 2 shows these limits as a function of the mass of the EGM W′ boson and the ρTC particle along with the combined statistical and systematic uncertainties. Fig. 3 shows the LSTC cross section limits in a two-dimensional plane as a function of the ρTC and πTC masses. The W′ production cross section and the branching fraction B(W′ → WZ) are affected by the strength of the coupling between the W′ boson and WZ, which we refer to as gW′WZ. The EGM as- sumes that gW′WZ = gWWZ × MWMZ/M2 W′ where gWWZ is the SM WWZ coupling and MW′ , MZ, and MW are the masses of the W′ , Z, and W particles, respectively. If the coupling between the W′ bo- son and WZ happens to be stronger than that predicted by the EGM, the observed and expected limits will be more stringent. This is illustrated in Fig. 4, where an upper limit at 95% CL on the W′WZ coupling is given as a function of the mass of the W′ resonance. 7. Summary A search has been performed in proton–proton collisions at √ s = 8 TeV for new particles decaying via WZ to fully leptonic final states with electrons, muons, and neutrinos. The data set cor- responds to an integrated luminosity of 19.5 fb−1. No significant excess is found in the mass distribution of the WZ candidates compared to the background expectation from standard model processes. The results are interpreted in the context of different theoretical models and stringent lower bounds are set at 95% con- Fig. 4. The 95% CL upper limit on the strength of W′WZ coupling normalized to the EGM prediction as a function of the W′ mass. The 1σ and 2σ combined sta- tistical and systematic uncertainties are indicated by the green (dark) and yellow (light) bands, respectively. PDF uncertainties on the theoretical cross section are not included. fidence level on the masses of hypothetical particles decaying via WZ to the fully leptonic final state. Assuming an extended gauge model, an expected (observed) exclusion limit of 1.55 (1.47) TeV on the mass of the W′ boson is set. Low-scale technicolor ρTC hadrons with masses below 1.14 TeV are also excluded assum- ing MπTC = 3 4 MρTC − 25 GeV. These exclusion limits represent a large improvement over previously published results obtained in proton–proton collisions with √ s = 7 TeV. Acknowledgements We congratulate our colleagues in the CERN accelerator depart- ments for the excellent performance of the LHC and thank the technical and administrative staffs at CERN and at other CMS in- stitutes for their contributions to the success of the CMS effort. In addition, we gratefully acknowledge the computing centers and personnel of the Worldwide LHC Computing Grid for delivering so effectively the computing infrastructure essential to our analyses. Finally, we acknowledge the enduring support for the construc- tion and operation of the LHC and the CMS detector provided by the following funding agencies: BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MOST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); MoER, ERC IUT and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS and RFBR (Russia); MESTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie programme and the European Research Council and EPLANET CMS Collaboration / Physics Letters B 740 (2015) 83–104 89 (European Union); the Leventis Foundation; the Alfred P. Sloan Foundation; the Alexander von Humboldt-Stiftung; the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT- Belgium); the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Council of Science and Industrial Research, India; the HOMING PLUS programme of Foundation For Polish Science, cofinanced from European Union, Regional Development Fund; the Compagnia di San Paolo (Torino); the Consorzio per la Fisica (Trieste); MIUR project 20108T4XTM (Italy); the Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF; and the National Priorities Research Program by Qatar National Re- search Fund. References [1] J.C. Pati, A. Salam, Lepton number as the fourth ‘color’, Phys. Rev. D 10 (1974) 275, http://dx.doi.org/10.1103/PhysRevD.10.275; J.C. Pati, A. Salam, Phys. Rev. D 11 (1975) 703, http://dx.doi.org/10.1103/ PhysRevD.11.703.2 (Erratum). [2] G. Altarelli, B. Mele, M. Ruiz-Altaba, Searching for new heavy vector bosons in pp̄ colliders, Z. Phys. C 45 (1989) 109, http://dx.doi.org/10.1007/BF01556677; G. Altarelli, B. Mele, M. Ruiz-Altaba, Z. Phys. C 47 (1990) 676 (Erratum). [3] A. Birkedal, K. Matchev, M. Perelstein, Collider phenomenology of the Hig- gsless models, Phys. Rev. Lett. 94 (2005) 191803, http://dx.doi.org/10.1103/ PhysRevLett.94.191803, arXiv:hep-ph/0412278. [4] M. Perelstein, Little Higgs models and their phenomenology, Prog. Part. Nucl. Phys. 58 (2007) 247, http://dx.doi.org/10.1016/j.ppnp.2006.04.001, arXiv: hep-ph/0512128. [5] K. Agashe, S. Gopalakrishna, T. Han, G.-Y. Huang, A. Soni, LHC signals for warped electroweak charged gauge bosons, Phys. Rev. D 80 (2009) 075007, http://dx.doi.org/10.1103/PhysRevD.80.075007, arXiv:0810.1497. [6] C. Grojean, E. Salvioni, R. Torre, A weakly constrained W′ at the early LHC, J. High Energy Phys. 07 (2011) 002, http://dx.doi.org/10.1007/JHEP07(2011)002, arXiv:1103.2761v3. [7] J. Beringer, et al., Particle Data Group, Review of particle physics, Phys. Rev. D 86 (2012) 010001, http://dx.doi.org/10.1103/PhysRevD.86.010001. [8] H.-J. He, Y.-P. Kuang, Y.-H. Qi, B. Zhang, A. Belyaev, R.S. Chivukula, N.D. Chris- tensen, A. Pukhov, E.H. Simmons, CERN LHC signatures of new gauge bosons in the minimal Higgsless model, Phys. Rev. D 78 (2008) 031701, http://dx.doi.org/ 10.1103/PhysRevD.78.031701, arXiv:0708.2588v2. [9] CMS Collaboration, Search for new physics in final states with a lepton and missing transverse energy in pp collisions at the LHC, Phys. Rev. D 87 (2013) 072005, http://dx.doi.org/10.1103/PhysRevD.87.072005, arXiv:1302.2812. [10] CMS Collaboration, Search for leptonic decays of W′ bosons in pp collisions at √s = 7 TeV, J. High Energy Phys. 08 (2012) 023, http://dx.doi.org/10.1007/ JHEP08(2012)023, arXiv:1204.4764. [11] ATLAS Collaboration, ATLAS search for a heavy gauge boson decaying to a charged lepton and a neutrino in pp collisions at √ s = 7 TeV, Eur. Phys. J. C 72 (2012) 2241, http://dx.doi.org/10.1140/epjc/s10052-012-2241-5, arXiv:1209.4446. [12] CMS Collaboration, Search for narrow resonances using the dijet mass spec- trum in pp collisions at √s = 8 TeV, Phys. Rev. D 87 (2013) 114015, http:// dx.doi.org/10.1103/PhysRevD.87.114015, arXiv:1302.4794. [13] ATLAS Collaboration, ATLAS search for new phenomena in dijet mass and an- gular distributions using pp collisions at √s = 7 TeV, J. High Energy Phys. 01 (2013) 029, http://dx.doi.org/10.1007/JHEP01(2013)029, arXiv:1210.1718. [14] CMS Collaboration, Search for a W′ boson decaying to a bottom quark and a top quark in pp collisions at √s = 7 TeV, Phys. Lett. B 718 (2013) 1229, http:// dx.doi.org/10.1016/j.physletb.2012.12.008, arXiv:1208.0956. [15] ATLAS Collaboration, Search for tb resonances in proton–proton collisions at √ s = 7 TeV with the ATLAS detector, Phys. Rev. Lett. 109 (2012) 081801, http:// dx.doi.org/10.1103/PhysRevLett.109.081801, arXiv:1205.1016. [16] CMS Collaboration, Search for W′ to tb decays in the lepton + jets final state in pp collisions at √s = 8 TeV, J. High Energy Phys. 05 (2014) 108, http:// dx.doi.org/10.1007/JHEP05(2014)108, arXiv:1402.2176. [17] ATLAS Collaboration, Search for new particles in events with one lepton and missing transverse momentum in pp collisions at √s = 8 TeV with the ATLAS detector, J. High Energy Phys. 09 (2014) 037, http://dx.doi.org/10.1007/ JHEP09(2014)037, arXiv:1407.7494. [18] ATLAS Collaboration, Search for new phenomena in the dijet mass distribution using pp collision data at √s = 8 TeV with the ATLAS detector, Phys. Rev. D (2014), submitted for publication, arXiv:1407.1376. [19] ATLAS Collaboration, Search for W ′ → tb → qqbb decays in pp collisions at √ s = 8 TeV with the ATLAS detector, Eur. Phys. J. C (2014), submitted for pub- lication, arXiv:1408.0886. [20] L. Susskind, Dynamics of spontaneous symmetry breaking in the Weinberg– Salam theory, Phys. Rev. D 20 (1979) 2619, http://dx.doi.org/10.1103/ PhysRevD.20.2619. [21] K. Lane, Technihadron production and decay in low-scale technicolor, Phys. Rev. D 60 (1999) 075007, http://dx.doi.org/10.1103/PhysRevD.60.075007, arXiv: hep-ph/9903369. [22] E. Eichten, K. Lane, Low-scale technicolor at the Tevatron and LHC, Phys. Lett. B 669 (2008) 235, http://dx.doi.org/10.1016/j.physletb.2008.09.047, arXiv: 0706.2339. [23] V.M. Abazov, et al., D0 Collaboration, Search for a resonance decaying into WZ boson pairs in pp̄ collisions, Phys. Rev. Lett. 104 (2010) 061801, http:// dx.doi.org/10.1103/PhysRevLett.104.061801, arXiv:0912.0715v3. [24] ATLAS Collaboration, Search for resonant W Z production in the W Z → �ν�′�′ channel in √ s = 7 TeV pp collisions with the ATLAS detector, Phys. Rev. D 85 (2012) 112012, http://dx.doi.org/10.1103/PhysRevD.85.112012, arXiv: 1204.1648. [25] CMS Collaboration, Search for a W ′ or techni-ρ decaying into W Z in pp col- lisions at √s = 7 TeV, Phys. Rev. Lett. 109 (2012) 141801, http://dx.doi.org/ 10.1103/PhysRevLett.109.141801, arXiv:1206.0433. [26] ATLAS Collaboration, Search for W Z resonances in the fully leptonic chan- nel using pp collisions at √ s = 8 TeV with the ATLAS detector, Phys. Lett. B 737 (2014) 223, http://dx.doi.org/10.1016/j.physletb.2014.08.039, arXiv: 1406.4456. [27] T. Aaltonen, et al., CDF Collaboration, Search for w w and wz reso- nances decaying to electron, missing ET , and two jets in pp̄ collisions at √ s = 1.96 TeV, Phys. Rev. Lett. 104 (2010) 241801, http://dx.doi.org/10.1103/ PhysRevLett.104.241801, arXiv:1004.4946. [28] CMS Collaboration, Search for heavy resonances in the W/Z-tagged dijet mass spectrum in pp collisions at 7 TeV, Phys. Lett. B 723 (2013) 280, http:// dx.doi.org/10.1016/j.physletb.2013.05.040, arXiv:1212.1910. [29] CMS Collaboration, Search for exotic resonances decaying into WZ/ZZ in pp collisions at √s = 7 TeV, J. High Energy Phys. 02 (2013) 036, http://dx.doi.org/ 10.1007/JHEP02(2013)036, arXiv:1211.5779. [30] ATLAS Collaboration, Search for resonant diboson production in the WW/WZ → �ν j j decay channels with the ATLAS detector at √s = 7 TeV, Phys. Rev. D 87 (2013) 112006, http://dx.doi.org/10.1103/PhysRevD.87.112006, arXiv: 1305.0125. [31] CMS Collaboration, Search for massive resonances in dijet systems containing jets tagged as W or Z boson decays in pp collisions at √s = 8 TeV, J. High Energy Phys. 08 (2014) 173, http://dx.doi.org/10.1007/JHEP08(2014)173, arXiv: 1405.1994. [32] CMS Collaboration, Search for massive resonances decaying into pairs of boosted bosons in semi-leptonic final states at √ s = 8 TeV, J. High En- ergy Phys. 08 (2014) 174, http://dx.doi.org/10.1007/JHEP08(2014)174, arXiv: 1405.3447. [33] CMS Collaboration, Energy calibration and resolution of the CMS electromag- netic calorimeter in pp collisions at √s = 7 TeV, J. Instrum. 8 (2013) P09009, http://dx.doi.org/10.1088/1748-0221/8/09/P09009, arXiv:1306.2016. [34] CMS Collaboration, Performance of CMS muon reconstruction in pp collision events at √s = 7 TeV, J. Instrum. 7 (2012) P10002, http://dx.doi.org/10.1088/ 1748-0221/7/10/P10002, arXiv:1206.4071. [35] CMS Collaboration, Particle-flow event reconstruction in CMS and performance for jets, taus, and Emiss T , CMS Physics Analysis Summary CMS-PAS-PFT-09-001, 2009, http://cdsweb.cern.ch/record/1194487. [36] CMS Collaboration, Commissioning of the particle-flow event reconstruction with the first LHC collisions recorded in the CMS detector, CMS Physics Analysis Summary, CMS-PAS-PFT-10-001, 2010, http://cdsweb.cern.ch/record/ 1247373. [37] CMS Collaboration, The CMS experiment at the CERN LHC, J. Instrum. 3 (2008) S08004, http://dx.doi.org/10.1088/1748-0221/3/08/S08004. [38] T. Sjöstrand, S. Mrenna, P.Z. Skands, Pythia 6.4 physics and manual, J. High En- ergy Phys. 05 (2006), http://dx.doi.org/10.1088/1126-6708/2006/05/026, arXiv: hep-ph/0603175. [39] J. Pumplin, D.R. Stump, J. Huston, H.-L. Lai, P. Nadolsky, W.-K. Tung, New gen- eration of parton distributions with uncertainties from global QCD analysis, J. High Energy Phys. 07 (2002) 012, http://dx.doi.org/10.1088/1126-6708/2002/ 07/012, arXiv:hep-ph/0201195. [40] CMS Collaboration, Measurement of the underlying event activity at the LHC with √s = 7 TeV and comparison with √s = 0.9 TeV, J. High Energy Phys. 09 (2011) 109, http://dx.doi.org/10.1007/JHEP09(2011)109, arXiv:1107.0330. [41] R. Gavin, Y. Li, F. Petriello, S. Quackenbush, FEWZ 2.0: a code for hadronic Z production at next-to-next-to-leading order, Comput. Phys. Commun. 182 (2011) 2388, http://dx.doi.org/10.1016/j.cpc.2011.06.008. [42] G. Brooijmans, et al., New Physics Working Group, New physics at the LHC: a Les Houches report. Physics at TeV colliders 2009, arXiv:1005.1229, 2010. [43] J. Alwall, R. Frederix, S. Frixione, V. Hirschi, F. Maltoni, O. Mattelaer, H.-S. Shao, T. Stelzer, P. Torrielli, M. Zaro, The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations, arXiv:1405.0301, 2014. http://dx.doi.org/10.1103/PhysRevD.10.275 http://dx.doi.org/10.1103/PhysRevD.11.703.2 http://dx.doi.org/10.1007/BF01556677 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib73736D33s2 http://dx.doi.org/10.1103/PhysRevLett.94.191803 http://dx.doi.org/10.1016/j.ppnp.2006.04.001 http://dx.doi.org/10.1103/PhysRevD.80.075007 http://dx.doi.org/10.1007/JHEP07(2011)002 http://dx.doi.org/10.1103/PhysRevD.86.010001 http://dx.doi.org/10.1103/PhysRevD.78.031701 http://dx.doi.org/10.1103/PhysRevD.87.072005 http://dx.doi.org/10.1007/JHEP08(2012)023 http://dx.doi.org/10.1140/epjc/s10052-012-2241-5 http://dx.doi.org/10.1103/PhysRevD.87.114015 http://dx.doi.org/10.1007/JHEP01(2013)029 http://dx.doi.org/10.1016/j.physletb.2012.12.008 http://dx.doi.org/10.1103/PhysRevLett.109.081801 http://dx.doi.org/10.1007/JHEP05(2014)108 http://dx.doi.org/10.1007/JHEP09(2014)037 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib4161643A32303134617161s1 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib4161643A32303134617161s1 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib4161643A32303134617161s1 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib4161643A32303134787261s1 http://dx.doi.org/10.1103/PhysRevD.20.2619 http://dx.doi.org/10.1103/PhysRevD.60.075007 http://dx.doi.org/10.1016/j.physletb.2008.09.047 http://dx.doi.org/10.1103/PhysRevLett.104.061801 http://dx.doi.org/10.1103/PhysRevD.85.112012 http://dx.doi.org/10.1103/PhysRevLett.109.141801 http://dx.doi.org/10.1016/j.physletb.2014.08.039 http://dx.doi.org/10.1103/PhysRevLett.104.241801 http://dx.doi.org/10.1016/j.physletb.2013.05.040 http://dx.doi.org/10.1007/JHEP02(2013)036 http://dx.doi.org/10.1103/PhysRevD.87.112006 http://dx.doi.org/10.1007/JHEP08(2014)173 http://dx.doi.org/10.1007/JHEP08(2014)174 http://dx.doi.org/10.1088/1748-0221/8/09/P09009 http://dx.doi.org/10.1088/1748-0221/7/10/P10002 http://cdsweb.cern.ch/record/1194487 http://cdsweb.cern.ch/record/1247373 http://cdsweb.cern.ch/record/1247373 http://dx.doi.org/10.1088/1748-0221/3/08/S08004 http://dx.doi.org/10.1088/1126-6708/2006/05/026 http://dx.doi.org/10.1088/1126-6708/2002/07/012 http://dx.doi.org/10.1007/JHEP09(2011)109 http://dx.doi.org/10.1016/j.cpc.2011.06.008 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib4C6573486F75636865733039s1 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib4C6573486F75636865733039s1 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib4C6573486F75636865733039s1 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib6D61646772617068s1 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib6D61646772617068s1 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib6D61646772617068s1 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib6D61646772617068s1 http://dx.doi.org/10.1103/PhysRevD.11.703.2 http://dx.doi.org/10.1103/PhysRevLett.94.191803 http://dx.doi.org/10.1103/PhysRevD.78.031701 http://dx.doi.org/10.1007/JHEP08(2012)023 http://dx.doi.org/10.1103/PhysRevD.87.114015 http://dx.doi.org/10.1016/j.physletb.2012.12.008 http://dx.doi.org/10.1103/PhysRevLett.109.081801 http://dx.doi.org/10.1007/JHEP05(2014)108 http://dx.doi.org/10.1007/JHEP09(2014)037 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib4161643A32303134787261s1 http://dx.doi.org/10.1103/PhysRevD.20.2619 http://dx.doi.org/10.1103/PhysRevLett.104.061801 http://dx.doi.org/10.1103/PhysRevLett.109.141801 http://dx.doi.org/10.1103/PhysRevLett.104.241801 http://dx.doi.org/10.1016/j.physletb.2013.05.040 http://dx.doi.org/10.1007/JHEP02(2013)036 http://dx.doi.org/10.1088/1748-0221/7/10/P10002 http://dx.doi.org/10.1088/1126-6708/2002/07/012 90 CMS Collaboration / Physics Letters B 740 (2015) 83–104 [44] P. Nason, A new method for combining NLO QCD with shower Monte Carlo algorithms, J. High Energy Phys. 11 (2004) 040, http://dx.doi.org/10.1088/ 1126-6708/2004/11/040, arXiv:hep-ph/0409146. [45] S. Frixione, P. Nason, C. Oleari, Matching NLO QCD computations with parton shower simulations: the POWHEG method, J. High Energy Phys. 11 (2007) 070, http://dx.doi.org/10.1088/1126-6708/2007/11/070, arXiv:0709.2092. [46] S. Alioli, P. Nason, C. Oleari, E. Re, A general framework for implementing NLO calculations in shower Monte Carlo programs: the POWHEG BOX, J. High Energy Phys. 06 (2010) 043, http://dx.doi.org/10.1007/JHEP06(2010)043, arXiv: 1002.2581. [47] T. Melia, P. Nason, R. Röntsch, G. Zanderighi, W +W − , W Z and Z Z production in the POWHEG BOX, J. High Energy Phys. 11 (2011) 078, http://dx.doi.org/ 10.1007/JHEP11(2011)078, arXiv:1107.5051. [48] S. Agostinelli, et al., GEANT4 Collaboration, GEANT4—a simulation toolkit, Nucl. Instrum. Methods Phys. Res., Sect. A 506 (2003) 250, http://dx.doi.org/10.1016/ S0168-9002(03)01368-8. [49] CMS Collaboration, Measurement of the inclusive W and Z production cross sections in pp collisions at √s = 7 TeV, J. High Energy Phys. 10 (2011) 132, http://dx.doi.org/10.1007/JHEP10(2011)132, arXiv:1107.4789. [50] W. Adam, R. Frühwirth, A. Strandlie, T. Todorov, Reconstruction of electrons with the Gaussian sum filter in the CMS tracker at LHC, J. Phys. G 31 (2005) N9, http://dx.doi.org/10.1088/0954-3899/31/9/N01, arXiv:physics/0306087. [51] M. Cacciari, G.P. Salam, Pileup subtraction using jet areas, Phys. Lett. B 659 (2008) 119, http://dx.doi.org/10.1016/j.physletb.2007.09.077, arXiv:0707.1378. [52] CMS Collaboration, Search for neutral Higgs bosons decaying to tau pairs in pp collisions at √s = 7 TeV, Phys. Lett. B 713 (2012) 68, http://dx.doi.org/10.1016/ j.physletb.2012.05.028, arXiv:1202.4083. [53] S. Alekhin, et al., The PDF4LHC working group interim report, arXiv:1101.0536, 2011. [54] M. Botje, J. Butterworth, A. Cooper-Sarkar, A. de Roeck, J. Feltesse, S. Forte, A. Glazov, J. Huston, R. McNulty, T. Sjöstrand, R.S. Thorne, The PDF4LHC work- ing group interim recommendations, arXiv:1101.0538, 2011. [55] A.D. Martin, W.J. Stirling, R.S. Thorne, G. Watt, Parton distributions for the LHC, Eur. Phys. J. C 63 (2009) 189, http://dx.doi.org/10.1140/epjc/ s10052-009-1072-5, arXiv:0901.0002. [56] P.M. Nadolsky, H.-L. Lai, Q.-H. Cao, J. Huston, J. Pumplin, D. Stump, W.-K. Tung, C.-P. Yuan, Implications of CTEQ global analysis for collider observables, Phys. Rev. D 78 (2008) 013004, http://dx.doi.org/10.1103/PhysRevD.78.013004, arXiv: 0802.0007. [57] R.D. Ball, V. Bertone, F. Cerutti, L. Del Debbio, S. Forte, A. Guffanti, J.I. La- torre, J. Rojo, M. Ubiali, NNPDF Collaboration, Impact of heavy quark masses on parton distributions and LHC phenomenology, Nucl. Phys. B 849 (2011) 296, http://dx.doi.org/10.1016/j.nuclphysb.2011.03.021, arXiv:1101.1300. [58] J.M. Campbell, R.K. Ellis, MCFM for the Tevatron and the LHC, Nucl. Phys. B, Proc. Suppl. 205 (2010) 10, http://dx.doi.org/10.1016/j.nuclphysbps. 2010.08.011, arXiv:1007.3492. [59] CMS Collaboration, CMS luminosity based on pixel cluster counting – sum- mer 2013 update, CMS Physics Analysis Summary, CMS-PAS-LUM-13-001, 2013, http://cdsweb.cern.ch/record/1598864. [60] L. Moneta, K. Belasco, K.S. Cranmer, A. Lazzaro, D. Piparo, G. Schott, W. Verk- erke, M. Wolf, The RooStats project, in: 13th International Workshop on Ad- vanced Computing and Analysis Techniques in Physics Research, ACAT2010, SISSA, 2010, http://pos.sissa.it/archive/conferences/093/057/ACAT2010_057.pdf, arXiv:1009.1003, PoS ACAT (2010) 057. CMS Collaboration V. Khachatryan, A.M. Sirunyan, A. Tumasyan Yerevan Physics Institute, Yerevan, Armenia W. Adam, T. Bergauer, M. Dragicevic, J. Erö, C. Fabjan 1, M. Friedl, R. Frühwirth 1, V.M. Ghete, C. Hartl, N. Hörmann, J. Hrubec, M. Jeitler 1, W. Kiesenhofer, V. Knünz, M. Krammer 1, I. Krätschmer, D. Liko, I. Mikulec, D. Rabady 2, B. Rahbaran, H. Rohringer, R. Schöfbeck, J. Strauss, A. Taurok, W. Treberer-Treberspurg, W. Waltenberger, C.-E. Wulz 1 Institut für Hochenergiephysik der OeAW, Wien, Austria V. Mossolov, N. Shumeiko, J. Suarez Gonzalez National Centre for Particle and High Energy Physics, Minsk, Belarus S. Alderweireldt, M. Bansal, S. Bansal, T. Cornelis, E.A. De Wolf, X. Janssen, A. Knutsson, S. Luyckx, S. Ochesanu, B. Roland, R. Rougny, M. Van De Klundert, H. Van Haevermaet, P. Van Mechelen, N. Van Remortel, A. Van Spilbeeck Universiteit Antwerpen, Antwerpen, Belgium F. Blekman, S. Blyweert, J. D’Hondt, N. Daci, N. Heracleous, J. Keaveney, T.J. Kim, S. Lowette, M. Maes, A. Olbrechts, Q. Python, D. Strom, S. Tavernier, W. Van Doninck, P. Van Mulders, G.P. Van Onsem, I. Villella Vrije Universiteit Brussel, Brussel, Belgium C. Caillol, B. Clerbaux, G. De Lentdecker, D. Dobur, L. Favart, A.P.R. Gay, A. Grebenyuk, A. Léonard, A. Mohammadi, L. Perniè 2, T. Reis, T. Seva, L. Thomas, C. Vander Velde, P. Vanlaer, J. Wang Université Libre de Bruxelles, Bruxelles, Belgium V. Adler, K. Beernaert, L. Benucci, A. Cimmino, S. Costantini, S. Crucy, S. Dildick, A. Fagot, G. Garcia, J. Mccartin, A.A. Ocampo Rios, D. Ryckbosch, S. Salva Diblen, M. Sigamani, N. Strobbe, F. Thyssen, M. Tytgat, E. Yazgan, N. Zaganidis Ghent University, Ghent, Belgium http://dx.doi.org/10.1088/1126-6708/2004/11/040 http://dx.doi.org/10.1088/1126-6708/2007/11/070 http://dx.doi.org/10.1007/JHEP06(2010)043 http://dx.doi.org/10.1007/JHEP11(2011)078 http://dx.doi.org/10.1016/S0168-9002(03)01368-8 http://dx.doi.org/10.1007/JHEP10(2011)132 http://dx.doi.org/10.1088/0954-3899/31/9/N01 http://dx.doi.org/10.1016/j.physletb.2007.09.077 http://dx.doi.org/10.1016/j.physletb.2012.05.028 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib416C656B68696E3A32303131736Bs1 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib416C656B68696E3A32303131736Bs1 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib504446344C4843s1 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib504446344C4843s1 http://refhub.elsevier.com/S0370-2693(14)00828-4/bib504446344C4843s1 http://dx.doi.org/10.1140/epjc/s10052-009-1072-5 http://dx.doi.org/10.1103/PhysRevD.78.013004 http://dx.doi.org/10.1016/j.nuclphysb.2011.03.021 http://dx.doi.org/10.1016/j.nuclphysbps.2010.08.011 http://cdsweb.cern.ch/record/1598864 http://pos.sissa.it/archive/conferences/093/057/ACAT2010_057.pdf http://dx.doi.org/10.1088/1126-6708/2004/11/040 http://dx.doi.org/10.1007/JHEP11(2011)078 http://dx.doi.org/10.1016/S0168-9002(03)01368-8 http://dx.doi.org/10.1016/j.physletb.2012.05.028 http://dx.doi.org/10.1140/epjc/s10052-009-1072-5 http://dx.doi.org/10.1016/j.nuclphysbps.2010.08.011 CMS Collaboration / Physics Letters B 740 (2015) 83–104 91 S. Basegmez, C. Beluffi 3, G. Bruno, R. Castello, A. Caudron, L. Ceard, G.G. Da Silveira, C. Delaere, T. du Pree, D. Favart, L. Forthomme, A. Giammanco 4, J. Hollar, P. Jez, M. Komm, V. Lemaitre, J. Liao, C. Nuttens, D. Pagano, L. Perrini, A. Pin, K. Piotrzkowski, A. Popov 5, L. Quertenmont, M. Selvaggi, M. Vidal Marono, J.M. Vizan Garcia Université Catholique de Louvain, Louvain-la-Neuve, Belgium N. Beliy, T. Caebergs, E. Daubie, G.H. Hammad Université de Mons, Mons, Belgium W.L. Aldá Júnior, G.A. Alves, M. Correa Martins Junior, T. Dos Reis Martins, M.E. Pol Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil W. Carvalho, J. Chinellato 6, A. Custódio, E.M. Da Costa, D. De Jesus Damiao, C. De Oliveira Martins, S. Fonseca De Souza, H. Malbouisson, D. Matos Figueiredo, L. Mundim, H. Nogima, W.L. Prado Da Silva, J. Santaolalla, A. Santoro, A. Sznajder, E.J. Tonelli Manganote 6, A. Vilela Pereira Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil C.A. Bernardes b, F.A. Dias a,7, T.R. Fernandez Perez Tomei a, E.M. Gregores b, P.G. Mercadante b, S.F. Novaes a, Sandra S. Padula a a Universidade Estadual Paulista, São Paulo, Brazil b Universidade Federal do ABC, São Paulo, Brazil A. Aleksandrov, V. Genchev 2, P. Iaydjiev, A. Marinov, S. Piperov, M. Rodozov, G. Sultanov, M. Vutova Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria A. Dimitrov, I. Glushkov, R. Hadjiiska, V. Kozhuharov, L. Litov, B. Pavlov, P. Petkov University of Sofia, Sofia, Bulgaria J.G. Bian, G.M. Chen, H.S. Chen, M. Chen, R. Du, C.H. Jiang, D. Liang, S. Liang, R. Plestina 8, J. Tao, X. Wang, Z. Wang Institute of High Energy Physics, Beijing, China C. Asawatangtrakuldee, Y. Ban, Y. Guo, Q. Li, W. Li, S. Liu, Y. Mao, S.J. Qian, D. Wang, L. Zhang, W. Zou State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China C. Avila, L.F. Chaparro Sierra, C. Florez, J.P. Gomez, B. Gomez Moreno, J.C. Sanabria Universidad de Los Andes, Bogota, Colombia N. Godinovic, D. Lelas, D. Polic, I. Puljak Technical University of Split, Split, Croatia Z. Antunovic, M. Kovac University of Split, Split, Croatia V. Brigljevic, K. Kadija, J. Luetic, D. Mekterovic, L. Sudic Institute Rudjer Boskovic, Zagreb, Croatia A. Attikis, G. Mavromanolakis, J. Mousa, C. Nicolaou, F. Ptochos, P.A. Razis University of Cyprus, Nicosia, Cyprus M. Bodlak, M. Finger, M. Finger Jr. 9 Charles University, Prague, Czech Republic 92 CMS Collaboration / Physics Letters B 740 (2015) 83–104 Y. Assran 10, S. Elgammal 11, M.A. Mahmoud 12, A. Radi 11,13 Academy of Scientific Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, Egypt M. Kadastik, M. Murumaa, M. Raidal, A. Tiko National Institute of Chemical Physics and Biophysics, Tallinn, Estonia P. Eerola, G. Fedi, M. Voutilainen Department of Physics, University of Helsinki, Helsinki, Finland J. Härkönen, V. Karimäki, R. Kinnunen, M.J. Kortelainen, T. Lampén, K. Lassila-Perini, S. Lehti, T. Lindén, P. Luukka, T. Mäenpää, T. Peltola, E. Tuominen, J. Tuominiemi, E. Tuovinen, L. Wendland Helsinki Institute of Physics, Helsinki, Finland T. Tuuva Lappeenranta University of Technology, Lappeenranta, Finland M. Besancon, F. Couderc, M. Dejardin, D. Denegri, B. Fabbro, J.L. Faure, C. Favaro, F. Ferri, S. Ganjour, A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry, E. Locci, J. Malcles, J. Rander, A. Rosowsky, M. Titov DSM/IRFU, CEA/Saclay, Gif-sur-Yvette, France S. Baffioni, F. Beaudette, P. Busson, C. Charlot, T. Dahms, M. Dalchenko, L. Dobrzynski, N. Filipovic, A. Florent, R. Granier de Cassagnac, L. Mastrolorenzo, P. Miné, C. Mironov, I.N. Naranjo, M. Nguyen, C. Ochando, P. Paganini, R. Salerno, J.B. Sauvan, Y. Sirois, C. Veelken, Y. Yilmaz, A. Zabi Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3–CNRS, Palaiseau, France J.-L. Agram 14, J. Andrea, A. Aubin, D. Bloch, J.-M. Brom, E.C. Chabert, C. Collard, E. Conte 14, J.-C. Fontaine 14, D. Gelé, U. Goerlach, C. Goetzmann, A.-C. Le Bihan, P. Van Hove Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Université de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France S. Gadrat Centre de Calcul de l’Institut National de Physique Nucleaire et de Physique des Particules, CNRS/IN2P3, Villeurbanne, France S. Beauceron, N. Beaupere, G. Boudoul 2, S. Brochet, C.A. Carrillo Montoya, J. Chasserat, R. Chierici, D. Contardo 2, P. Depasse, H. El Mamouni, J. Fan, J. Fay, S. Gascon, M. Gouzevitch, B. Ille, T. Kurca, M. Lethuillier, L. Mirabito, S. Perries, J.D. Ruiz Alvarez, D. Sabes, L. Sgandurra, V. Sordini, M. Vander Donckt, P. Verdier, S. Viret, H. Xiao Université de Lyon, Université Claude Bernard Lyon 1, CNRS–IN2P3, Institut de Physique Nucléaire de Lyon, Villeurbanne, France Z. Tsamalaidze 9 Institute of High Energy Physics and Informatization, Tbilisi State University, Tbilisi, Georgia C. Autermann, S. Beranek, M. Bontenackels, M. Edelhoff, L. Feld, O. Hindrichs, K. Klein, A. Ostapchuk, A. Perieanu, F. Raupach, J. Sammet, S. Schael, H. Weber, B. Wittmer, V. Zhukov 5 RWTH Aachen University, I. Physikalisches Institut, Aachen, Germany M. Ata, E. Dietz-Laursonn, D. Duchardt, M. Erdmann, R. Fischer, A. Güth, T. Hebbeker, C. Heidemann, K. Hoepfner, D. Klingebiel, S. Knutzen, P. Kreuzer, M. Merschmeyer, A. Meyer, M. Olschewski, K. Padeken, P. Papacz, H. Reithler, S.A. Schmitz, L. Sonnenschein, D. Teyssier, S. Thüer, M. Weber RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany CMS Collaboration / Physics Letters B 740 (2015) 83–104 93 V. Cherepanov, Y. Erdogan, G. Flügge, H. Geenen, M. Geisler, W. Haj Ahmad, F. Hoehle, B. Kargoll, T. Kress, Y. Kuessel, J. Lingemann 2, A. Nowack, I.M. Nugent, L. Perchalla, O. Pooth, A. Stahl RWTH Aachen University, III. Physikalisches Institut B, Aachen, Germany I. Asin, N. Bartosik, J. Behr, W. Behrenhoff, U. Behrens, A.J. Bell, M. Bergholz 15, A. Bethani, K. Borras, A. Burgmeier, A. Cakir, L. Calligaris, A. Campbell, S. Choudhury, F. Costanza, C. Diez Pardos, S. Dooling, T. Dorland, G. Eckerlin, D. Eckstein, T. Eichhorn, G. Flucke, J. Garay Garcia, A. Geiser, P. Gunnellini, J. Hauk, G. Hellwig, M. Hempel, D. Horton, H. Jung, A. Kalogeropoulos, M. Kasemann, P. Katsas, J. Kieseler, C. Kleinwort, D. Krücker, W. Lange, J. Leonard, K. Lipka, A. Lobanov, W. Lohmann 15, B. Lutz, R. Mankel, I. Marfin, I.-A. Melzer-Pellmann, A.B. Meyer, J. Mnich, A. Mussgiller, S. Naumann-Emme, A. Nayak, O. Novgorodova, F. Nowak, E. Ntomari, H. Perrey, D. Pitzl, R. Placakyte, A. Raspereza, P.M. Ribeiro Cipriano, E. Ron, M.Ö. Sahin, J. Salfeld-Nebgen, P. Saxena, R. Schmidt 15, T. Schoerner-Sadenius, M. Schröder, S. Spannagel, A.D.R. Vargas Trevino, R. Walsh, C. Wissing Deutsches Elektronen-Synchrotron, Hamburg, Germany M. Aldaya Martin, V. Blobel, M. Centis Vignali, J. Erfle, E. Garutti, K. Goebel, M. Görner, J. Haller, M. Hoffmann, R.S. Höing, H. Kirschenmann, R. Klanner, R. Kogler, J. Lange, T. Lapsien, T. Lenz, I. Marchesini, J. Ott, T. Peiffer, N. Pietsch, D. Rathjens, C. Sander, H. Schettler, P. Schleper, E. Schlieckau, A. Schmidt, M. Seidel, J. Sibille 16, V. Sola, H. Stadie, G. Steinbrück, D. Troendle, E. Usai, L. Vanelderen University of Hamburg, Hamburg, Germany C. Barth, C. Baus, J. Berger, C. Böser, E. Butz, T. Chwalek, W. De Boer, A. Descroix, A. Dierlamm, M. Feindt, F. Frensch, M. Giffels, F. Hartmann 2, T. Hauth 2, U. Husemann, I. Katkov 5, A. Kornmayer 2, E. Kuznetsova, P. Lobelle Pardo, M.U. Mozer, Th. Müller, A. Nürnberg, G. Quast, K. Rabbertz, F. Ratnikov, S. Röcker, H.J. Simonis, F.M. Stober, R. Ulrich, J. Wagner-Kuhr, S. Wayand, T. Weiler, R. Wolf Institut für Experimentelle Kernphysik, Karlsruhe, Germany G. Anagnostou, G. Daskalakis, T. Geralis, V.A. Giakoumopoulou, A. Kyriakis, D. Loukas, A. Markou, C. Markou, A. Psallidas, I. Topsis-Giotis Institute of Nuclear and Particle Physics (INPP), NCSR Demokritos, Aghia Paraskevi, Greece A. Panagiotou, N. Saoulidou, E. Stiliaris University of Athens, Athens, Greece X. Aslanoglou, I. Evangelou, G. Flouris, C. Foudas, P. Kokkas, N. Manthos, I. Papadopoulos, E. Paradas University of Ioánnina, Ioánnina, Greece G. Bencze, C. Hajdu, P. Hidas, D. Horvath 17, F. Sikler, V. Veszpremi, G. Vesztergombi 18, A.J. Zsigmond Wigner Research Centre for Physics, Budapest, Hungary N. Beni, S. Czellar, J. Karancsi 19, J. Molnar, J. Palinkas, Z. Szillasi Institute of Nuclear Research ATOMKI, Debrecen, Hungary P. Raics, Z.L. Trocsanyi, B. Ujvari University of Debrecen, Debrecen, Hungary S.K. Swain National Institute of Science Education and Research, Bhubaneswar, India S.B. Beri, V. Bhatnagar, N. Dhingra, R. Gupta, U. Bhawandeep, A.K. Kalsi, M. Kaur, M. Mittal, N. Nishu, J.B. Singh Panjab University, Chandigarh, India 94 CMS Collaboration / Physics Letters B 740 (2015) 83–104 Ashok Kumar, Arun Kumar, S. Ahuja, A. Bhardwaj, B.C. Choudhary, A. Kumar, S. Malhotra, M. Naimuddin, K. Ranjan, V. Sharma University of Delhi, Delhi, India S. Banerjee, S. Bhattacharya, K. Chatterjee, S. Dutta, B. Gomber, Sa. Jain, Sh. Jain, R. Khurana, A. Modak, S. Mukherjee, D. Roy, S. Sarkar, M. Sharan Saha Institute of Nuclear Physics, Kolkata, India A. Abdulsalam, D. Dutta, S. Kailas, V. Kumar, A.K. Mohanty 2, L.M. Pant, P. Shukla, A. Topkar Bhabha Atomic Research Centre, Mumbai, India T. Aziz, S. Banerjee, S. Bhowmik 20, R.M. Chatterjee, R.K. Dewanjee, S. Dugad, S. Ganguly, S. Ghosh, M. Guchait, A. Gurtu 21, G. Kole, S. Kumar, M. Maity 20, G. Majumder, K. Mazumdar, G.B. Mohanty, B. Parida, K. Sudhakar, N. Wickramage 22 Tata Institute of Fundamental Research, Mumbai, India H. Bakhshiansohi, H. Behnamian, S.M. Etesami 23, A. Fahim 24, R. Goldouzian, A. Jafari, M. Khakzad, M. Mohammadi Najafabadi, M. Naseri, S. Paktinat Mehdiabadi, B. Safarzadeh 25, M. Zeinali Institute for Research in Fundamental Sciences (IPM), Tehran, Iran M. Felcini, M. Grunewald University College Dublin, Dublin, Ireland M. Abbrescia a,b, L. Barbone a,b, C. Calabria a,b, S.S. Chhibra a,b, A. Colaleo a, D. Creanza a,c, N. De Filippis a,c, M. De Palma a,b, L. Fiore a, G. Iaselli a,c, G. Maggi a,c, M. Maggi a, S. My a,c, S. Nuzzo a,b, A. Pompili a,b, G. Pugliese a,c, R. Radogna a,b,2, G. Selvaggi a,b, L. Silvestris a,2, G. Singh a,b, R. Venditti a,b, P. Verwilligen a, G. Zito a a INFN Sezione di Bari, Bari, Italy b Università di Bari, Bari, Italy c Politecnico di Bari, Bari, Italy G. Abbiendi a, A.C. Benvenuti a, D. Bonacorsi a,b, S. Braibant-Giacomelli a,b, L. Brigliadori a,b, R. Campanini a,b, P. Capiluppi a,b, A. Castro a,b, F.R. Cavallo a, G. Codispoti a,b, M. Cuffiani a,b, G.M. Dallavalle a, F. Fabbri a, A. Fanfani a,b, D. Fasanella a,b, P. Giacomelli a, C. Grandi a, L. Guiducci a,b, S. Marcellini a, G. Masetti a,2, A. Montanari a, F.L. Navarria a,b, A. Perrotta a, F. Primavera a,b, A.M. Rossi a,b, T. Rovelli a,b, G.P. Siroli a,b, N. Tosi a,b, R. Travaglini a,b a INFN Sezione di Bologna, Bologna, Italy b Università di Bologna, Bologna, Italy S. Albergo a,b, G. Cappello a, M. Chiorboli a,b, S. Costa a,b, F. Giordano a,c,2, R. Potenza a,b, A. Tricomi a,b, C. Tuve a,b a INFN Sezione di Catania, Catania, Italy b Università di Catania, Catania, Italy c CSFNSM, Catania, Italy G. Barbagli a, V. Ciulli a,b, C. Civinini a, R. D’Alessandro a,b, E. Focardi a,b, E. Gallo a, S. Gonzi a,b, V. Gori a,b,2, P. Lenzi a,b, M. Meschini a, S. Paoletti a, G. Sguazzoni a, A. Tropiano a,b a INFN Sezione di Firenze, Firenze, Italy b Università di Firenze, Firenze, Italy L. Benussi, S. Bianco, F. Fabbri, D. Piccolo INFN Laboratori Nazionali di Frascati, Frascati, Italy CMS Collaboration / Physics Letters B 740 (2015) 83–104 95 F. Ferro a, M. Lo Vetere a,b, E. Robutti a, S. Tosi a,b a INFN Sezione di Genova, Genova, Italy b Università di Genova, Genova, Italy M.E. Dinardo a,b, S. Fiorendi a,b,2, S. Gennai a,2, R. Gerosa 2, A. Ghezzi a,b, P. Govoni a,b, M.T. Lucchini a,b,2, S. Malvezzi a, R.A. Manzoni a,b, A. Martelli a,b, B. Marzocchi, D. Menasce a, L. Moroni a, M. Paganoni a,b, D. Pedrini a, S. Ragazzi a,b, N. Redaelli a, T. Tabarelli de Fatis a,b a INFN Sezione di Milano–Bicocca, Milano, Italy b Università di Milano–Bicocca, Milano, Italy S. Buontempo a, N. Cavallo a,c, S. Di Guida a,d,2, F. Fabozzi a,c, A.O.M. Iorio a,b, L. Lista a, S. Meola a,d,2, M. Merola a, P. Paolucci a,2 a INFN Sezione di Napoli, Napoli, Italy b Università di Napoli ‘Federico II’, Napoli, Italy c Università della Basilicata (Potenza), Napoli, Italy d Università G. Marconi (Roma), Napoli, Italy P. Azzi a, M. Biasotto a,26, D. Bisello a,b, A. Branca a,b, R. Carlin a,b, P. Checchia a, M. Dall’Osso a,b, T. Dorigo a, U. Dosselli a, F. Fanzago a, M. Galanti a,b, F. Gasparini a,b, U. Gasparini a,b, A. Gozzelino a, K. Kanishchev a,c, S. Lacaprara a, M. Margoni a,b, A.T. Meneguzzo a,b, J. Pazzini a,b, N. Pozzobon a,b, P. Ronchese a,b, F. Simonetto a,b, E. Torassa a, M. Tosi a,b, P. Zotto a,b, A. Zucchetta a,b, G. Zumerle a,b a INFN Sezione di Padova, Padova, Italy b Università di Padova, Padova, Italy c Università di Trento (Trento), Padova, Italy M. Gabusi a,b, S.P. Ratti a,b, C. Riccardi a,b, P. Salvini a, P. Vitulo a,b a INFN Sezione di Pavia, Pavia, Italy b Università di Pavia, Pavia, Italy M. Biasini a,b, G.M. Bilei a, D. Ciangottini a,b, L. Fanò a,b, P. Lariccia a,b, G. Mantovani a,b, M. Menichelli a, F. Romeo a,b, A. Saha a, A. Santocchia a,b, A. Spiezia a,b,2 a INFN Sezione di Perugia, Perugia, Italy b Università di Perugia, Perugia, Italy K. Androsov a,27, P. Azzurri a, G. Bagliesi a, J. Bernardini a, T. Boccali a, G. Broccolo a,c, R. Castaldi a, M.A. Ciocci a,27, R. Dell’Orso a, S. Donato a,c, F. Fiori a,c, L. Foà a,c, A. Giassi a, M.T. Grippo a,27, F. Ligabue a,c, T. Lomtadze a, L. Martini a,b, A. Messineo a,b, C.S. Moon a,28, F. Palla a,2, A. Rizzi a,b, A. Savoy-Navarro a,29, A.T. Serban a, P. Spagnolo a, P. Squillacioti a,27, R. Tenchini a, G. Tonelli a,b, A. Venturi a, P.G. Verdini a, C. Vernieri a,c,2 a INFN Sezione di Pisa, Pisa, Italy b Università di Pisa, Pisa, Italy c Scuola Normale Superiore di Pisa, Pisa, Italy L. Barone a,b, F. Cavallari a, D. Del Re a,b, M. Diemoz a, M. Grassi a,b, C. Jorda a, E. Longo a,b, F. Margaroli a,b, P. Meridiani a, F. Micheli a,b,2, S. Nourbakhsh a,b, G. Organtini a,b, R. Paramatti a, S. Rahatlou a,b, C. Rovelli a, F. Santanastasio a,b, L. Soffi a,b,2, P. Traczyk a,b a INFN Sezione di Roma, Roma, Italy b Università di Roma, Roma, Italy N. Amapane a,b, R. Arcidiacono a,c, S. Argiro a,b,2, M. Arneodo a,c, R. Bellan a,b, C. Biino a, N. Cartiglia a, S. Casasso a,b,2, M. Costa a,b, A. Degano a,b, N. Demaria a, L. Finco a,b, C. Mariotti a, S. Maselli a, E. Migliore a,b, V. Monaco a,b, M. Musich a, M.M. Obertino a,c,2, G. Ortona a,b, L. Pacher a,b, N. Pastrone a, M. Pelliccioni a, G.L. Pinna Angioni a,b, A. Potenza a,b, A. Romero a,b, M. Ruspa a,c, R. Sacchi a,b, A. Solano a,b, A. Staiano a, U. Tamponi a a INFN Sezione di Torino, Torino, Italy b Università di Torino, Torino, Italy c Università del Piemonte Orientale (Novara), Torino, Italy 96 CMS Collaboration / Physics Letters B 740 (2015) 83–104 S. Belforte a, V. Candelise a,b, M. Casarsa a, F. Cossutti a, G. Della Ricca a,b, B. Gobbo a, C. La Licata a,b, M. Marone a,b, D. Montanino a,b, A. Schizzi a,b,2, T. Umer a,b, A. Zanetti a a INFN Sezione di Trieste, Trieste, Italy b Università di Trieste, Trieste, Italy S. Chang, A. Kropivnitskaya, S.K. Nam Kangwon National University, Chunchon, Republic of Korea D.H. Kim, G.N. Kim, M.S. Kim, D.J. Kong, S. Lee, Y.D. Oh, H. Park, A. Sakharov, D.C. Son Kyungpook National University, Daegu, Republic of Korea J.Y. Kim, S. Song Chonnam National University, Institute for Universe and Elementary Particles, Kwangju, Republic of Korea S. Choi, D. Gyun, B. Hong, M. Jo, H. Kim, Y. Kim, B. Lee, K.S. Lee, S.K. Park, Y. Roh Korea University, Seoul, Republic of Korea M. Choi, J.H. Kim, I.C. Park, S. Park, G. Ryu, M.S. Ryu University of Seoul, Seoul, Republic of Korea Y. Choi, Y.K. Choi, J. Goh, E. Kwon, J. Lee, H. Seo, I. Yu Sungkyunkwan University, Suwon, Republic of Korea A. Juodagalvis Vilnius University, Vilnius, Lithuania J.R. Komaragiri National Centre for Particle Physics, Universiti Malaya, Kuala Lumpur, Malaysia H. Castilla-Valdez, E. De La Cruz-Burelo, I. Heredia-de La Cruz 30, R. Lopez-Fernandez, A. Sanchez-Hernandez Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico S. Carrillo Moreno, F. Vazquez Valencia Universidad Iberoamericana, Mexico City, Mexico I. Pedraza, H.A. Salazar Ibarguen Benemerita Universidad Autonoma de Puebla, Puebla, Mexico E. Casimiro Linares, A. Morelos Pineda Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico D. Krofcheck University of Auckland, Auckland, New Zealand P.H. Butler, S. Reucroft University of Canterbury, Christchurch, New Zealand A. Ahmad, M. Ahmad, Q. Hassan, H.R. Hoorani, S. Khalid, W.A. Khan, T. Khurshid, M.A. Shah, M. Shoaib National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan CMS Collaboration / Physics Letters B 740 (2015) 83–104 97 H. Bialkowska, M. Bluj, B. Boimska, T. Frueboes, M. Górski, M. Kazana, K. Nawrocki, K. Romanowska-Rybinska, M. Szleper, P. Zalewski National Centre for Nuclear Research, Swierk, Poland G. Brona, K. Bunkowski, M. Cwiok, W. Dominik, K. Doroba, A. Kalinowski, M. Konecki, J. Krolikowski, M. Misiura, M. Olszewski, W. Wolszczak Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland P. Bargassa, C. Beirão Da Cruz E Silva, P. Faccioli, P.G. Ferreira Parracho, M. Gallinaro, F. Nguyen, J. Rodrigues Antunes, J. Seixas, J. Varela, P. Vischia Laboratório de Instrumentação e Física Experimental de Partículas, Lisboa, Portugal M. Gavrilenko, I. Golutvin, I. Gorbunov, A. Kamenev, V. Karjavin, V. Konoplyanikov, A. Lanev, A. Malakhov, V. Matveev 31, P. Moisenz, V. Palichik, V. Perelygin, M. Savina, S. Shmatov, S. Shulha, N. Skatchkov, V. Smirnov, A. Zarubin Joint Institute for Nuclear Research, Dubna, Russia V. Golovtsov, Y. Ivanov, V. Kim 32, P. Levchenko, V. Murzin, V. Oreshkin, I. Smirnov, V. Sulimov, L. Uvarov, S. Vavilov, A. Vorobyev, An. Vorobyev Petersburg Nuclear Physics Institute, Gatchina (St. Petersburg), Russia Yu. Andreev, A. Dermenev, S. Gninenko, N. Golubev, M. Kirsanov, N. Krasnikov, A. Pashenkov, D. Tlisov, A. Toropin Institute for Nuclear Research, Moscow, Russia V. Epshteyn, V. Gavrilov, N. Lychkovskaya, V. Popov, G. Safronov, S. Semenov, A. Spiridonov, V. Stolin, E. Vlasov, A. Zhokin Institute for Theoretical and Experimental Physics, Moscow, Russia V. Andreev, M. Azarkin, I. Dremin, M. Kirakosyan, A. Leonidov, G. Mesyats, S.V. Rusakov, A. Vinogradov P.N. Lebedev Physical Institute, Moscow, Russia A. Belyaev, E. Boos, V. Bunichev, M. Dubinin 7, L. Dudko, A. Ershov, A. Gribushin, V. Klyukhin, O. Kodolova, I. Lokhtin, S. Obraztsov, M. Perfilov, V. Savrin Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia I. Azhgirey, I. Bayshev, S. Bitioukov, V. Kachanov, A. Kalinin, D. Konstantinov, V. Krychkine, V. Petrov, R. Ryutin, A. Sobol, L. Tourtchanovitch, S. Troshin, N. Tyurin, A. Uzunian, A. Volkov State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, Russia P. Adzic 33, M. Dordevic, M. Ekmedzic, J. Milosevic University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia J. Alcaraz Maestre, C. Battilana, E. Calvo, M. Cerrada, M. Chamizo Llatas, N. Colino, B. De La Cruz, A. Delgado Peris, D. Domínguez Vázquez, A. Escalante Del Valle, C. Fernandez Bedoya, J.P. Fernández Ramos, J. Flix, M.C. Fouz, P. Garcia-Abia, O. Gonzalez Lopez, S. Goy Lopez, J.M. Hernandez, M.I. Josa, G. Merino, E. Navarro De Martino, A. Pérez-Calero Yzquierdo, J. Puerta Pelayo, A. Quintario Olmeda, I. Redondo, L. Romero, M.S. Soares Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain C. Albajar, J.F. de Trocóniz, M. Missiroli Universidad Autónoma de Madrid, Madrid, Spain 98 CMS Collaboration / Physics Letters B 740 (2015) 83–104 H. Brun, J. Cuevas, J. Fernandez Menendez, S. Folgueras, I. Gonzalez Caballero, L. Lloret Iglesias Universidad de Oviedo, Oviedo, Spain J.A. Brochero Cifuentes, I.J. Cabrillo, A. Calderon, J. Duarte Campderros, M. Fernandez, G. Gomez, A. Graziano, A. Lopez Virto, J. Marco, R. Marco, C. Martinez Rivero, F. Matorras, F.J. Munoz Sanchez, J. Piedra Gomez, T. Rodrigo, A.Y. Rodríguez-Marrero, A. Ruiz-Jimeno, L. Scodellaro, I. Vila, R. Vilar Cortabitarte Instituto de Física de Cantabria (IFCA), CSIC–Universidad de Cantabria, Santander, Spain D. Abbaneo, E. Auffray, G. Auzinger, M. Bachtis, P. Baillon, A.H. Ball, D. Barney, A. Benaglia, J. Bendavid, L. Benhabib, J.F. Benitez, C. Bernet 8, G. Bianchi, P. Bloch, A. Bocci, A. Bonato, O. Bondu, C. Botta, H. Breuker, T. Camporesi, G. Cerminara, S. Colafranceschi 34, M. D’Alfonso, D. d’Enterria, A. Dabrowski, A. David, F. De Guio, A. De Roeck, S. De Visscher, M. Dobson, N. Dupont-Sagorin, A. Elliott-Peisert, J. Eugster, G. Franzoni, W. Funk, D. Gigi, K. Gill, D. Giordano, M. Girone, F. Glege, R. Guida, S. Gundacker, M. Guthoff, J. Hammer, M. Hansen, P. Harris, J. Hegeman, V. Innocente, P. Janot, K. Kousouris, K. Krajczar, P. Lecoq, C. Lourenço, N. Magini, L. Malgeri, M. Mannelli, J. Marrouche, L. Masetti, F. Meijers, S. Mersi, E. Meschi, F. Moortgat, S. Morovic, M. Mulders, P. Musella, L. Orsini, L. Pape, E. Perez, L. Perrozzi, A. Petrilli, G. Petrucciani, A. Pfeiffer, M. Pierini, M. Pimiä, D. Piparo, M. Plagge, A. Racz, G. Rolandi 35, M. Rovere, H. Sakulin, C. Schäfer, C. Schwick, S. Sekmen, A. Sharma, P. Siegrist, P. Silva, M. Simon, P. Sphicas 36, D. Spiga, J. Steggemann, B. Stieger, M. Stoye, D. Treille, A. Tsirou, G.I. Veres 18, J.R. Vlimant, N. Wardle, H.K. Wöhri, H. Wollny, W.D. Zeuner CERN, European Organization for Nuclear Research, Geneva, Switzerland W. Bertl, K. Deiters, W. Erdmann, R. Horisberger, Q. Ingram, H.C. Kaestli, S. König, D. Kotlinski, U. Langenegger, D. Renker, T. Rohe Paul Scherrer Institut, Villigen, Switzerland F. Bachmair, L. Bäni, L. Bianchini, P. Bortignon, M.A. Buchmann, B. Casal, N. Chanon, A. Deisher, G. Dissertori, M. Dittmar, M. Donegà, M. Dünser, P. Eller, C. Grab, D. Hits, W. Lustermann, B. Mangano, A.C. Marini, P. Martinez Ruiz del Arbol, D. Meister, N. Mohr, C. Nägeli 37, F. Nessi-Tedaldi, F. Pandolfi, F. Pauss, M. Peruzzi, M. Quittnat, L. Rebane, M. Rossini, A. Starodumov 38, M. Takahashi, K. Theofilatos, R. Wallny, H.A. Weber Institute for Particle Physics, ETH Zurich, Zurich, Switzerland C. Amsler 39, M.F. Canelli, V. Chiochia, A. De Cosa, A. Hinzmann, T. Hreus, B. Kilminster, B. Millan Mejias, J. Ngadiuba, P. Robmann, F.J. Ronga, H. Snoek, S. Taroni, M. Verzetti, Y. Yang Universität Zürich, Zurich, Switzerland M. Cardaci, K.H. Chen, C. Ferro, C.M. Kuo, W. Lin, Y.J. Lu, R. Volpe, S.S. Yu National Central University, Chung-Li, Taiwan P. Chang, Y.H. Chang, Y.W. Chang, Y. Chao, K.F. Chen, P.H. Chen, C. Dietz, U. Grundler, W.-S. Hou, K.Y. Kao, Y.J. Lei, Y.F. Liu, R.-S. Lu, D. Majumder, E. Petrakou, Y.M. Tzeng, R. Wilken National Taiwan University (NTU), Taipei, Taiwan B. Asavapibhop, N. Srimanobhas, N. Suwonjandee Chulalongkorn University, Faculty of Science, Department of Physics, Bangkok, Thailand A. Adiguzel, M.N. Bakirci 40, S. Cerci 41, C. Dozen, I. Dumanoglu, E. Eskut, S. Girgis, G. Gokbulut, E. Gurpinar, I. Hos, E.E. Kangal, A. Kayis Topaksu, G. Onengut 42, K. Ozdemir, S. Ozturk 40, A. Polatoz, K. Sogut 43, D. Sunar Cerci 41, B. Tali 41, H. Topakli 40, M. Vergili Cukurova University, Adana, Turkey CMS Collaboration / Physics Letters B 740 (2015) 83–104 99 I.V. Akin, B. Bilin, S. Bilmis, H. Gamsizkan, G. Karapinar 44, K. Ocalan, U.E. Surat, M. Yalvac, M. Zeyrek Middle East Technical University, Physics Department, Ankara, Turkey E. Gülmez, B. Isildak 45, M. Kaya 46, O. Kaya 46 Bogazici University, Istanbul, Turkey H. Bahtiyar 47, E. Barlas, K. Cankocak, F.I. Vardarlı, M. Yücel Istanbul Technical University, Istanbul, Turkey L. Levchuk, P. Sorokin National Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, Ukraine J.J. Brooke, E. Clement, D. Cussans, H. Flacher, R. Frazier, J. Goldstein, M. Grimes, G.P. Heath, H.F. Heath, J. Jacob, L. Kreczko, C. Lucas, Z. Meng, D.M. Newbold 48, S. Paramesvaran, A. Poll, S. Senkin, V.J. Smith, T. Williams University of Bristol, Bristol, United Kingdom K.W. Bell, A. Belyaev 49, C. Brew, R.M. Brown, D.J.A. Cockerill, J.A. Coughlan, K. Harder, S. Harper, E. Olaiya, D. Petyt, C.H. Shepherd-Themistocleous, A. Thea, I.R. Tomalin, W.J. Womersley, S.D. Worm Rutherford Appleton Laboratory, Didcot, United Kingdom M. Baber, R. Bainbridge, O. Buchmuller, D. Burton, D. Colling, N. Cripps, M. Cutajar, P. Dauncey, G. Davies, M. Della Negra, P. Dunne, W. Ferguson, J. Fulcher, D. Futyan, A. Gilbert, G. Hall, G. Iles, M. Jarvis, G. Karapostoli, M. Kenzie, R. Lane, R. Lucas 48, L. Lyons, A.-M. Magnan, S. Malik, B. Mathias, J. Nash, A. Nikitenko 38, J. Pela, M. Pesaresi, K. Petridis, D.M. Raymond, S. Rogerson, A. Rose, C. Seez, P. Sharp †, A. Tapper, M. Vazquez Acosta, T. Virdee Imperial College, London, United Kingdom J.E. Cole, P.R. Hobson, A. Khan, P. Kyberd, D. Leggat, D. Leslie, W. Martin, I.D. Reid, P. Symonds, L. Teodorescu, M. Turner Brunel University, Uxbridge, United Kingdom J. Dittmann, K. Hatakeyama, A. Kasmi, H. Liu, T. Scarborough Baylor University, Waco, USA O. Charaf, S.I. Cooper, C. Henderson, P. Rumerio The University of Alabama, Tuscaloosa, USA A. Avetisyan, T. Bose, C. Fantasia, A. Heister, P. Lawson, C. Richardson, J. Rohlf, D. Sperka, J. St. John, L. Sulak Boston University, Boston, USA J. Alimena, E. Berry, S. Bhattacharya, G. Christopher, D. Cutts, Z. Demiragli, A. Ferapontov, A. Garabedian, U. Heintz, S. Jabeen, G. Kukartsev, E. Laird, G. Landsberg, M. Luk, M. Narain, M. Segala, T. Sinthuprasith, T. Speer, J. Swanson Brown University, Providence, USA R. Breedon, G. Breto, M. Calderon De La Barca Sanchez, S. Chauhan, M. Chertok, J. Conway, R. Conway, P.T. Cox, R. Erbacher, M. Gardner, W. Ko, R. Lander, T. Miceli, M. Mulhearn, D. Pellett, J. Pilot, F. Ricci-Tam, M. Searle, S. Shalhout, J. Smith, M. Squires, D. Stolp, M. Tripathi, S. Wilbur, R. Yohay University of California, Davis, Davis, USA 100 CMS Collaboration / Physics Letters B 740 (2015) 83–104 R. Cousins, P. Everaerts, C. Farrell, J. Hauser, M. Ignatenko, G. Rakness, E. Takasugi, V. Valuev, M. Weber University of California, Los Angeles, USA J. Babb, K. Burt, R. Clare, J. Ellison, J.W. Gary, G. Hanson, J. Heilman, M. Ivova Rikova, P. Jandir, E. Kennedy, F. Lacroix, H. Liu, O.R. Long, A. Luthra, M. Malberti, H. Nguyen, A. Shrinivas, S. Sumowidagdo, S. Wimpenny University of California, Riverside, Riverside, USA W. Andrews, J.G. Branson, G.B. Cerati, S. Cittolin, R.T. D’Agnolo, D. Evans, A. Holzner, R. Kelley, D. Klein, M. Lebourgeois, J. Letts, I. Macneill, D. Olivito, S. Padhi, C. Palmer, M. Pieri, M. Sani, V. Sharma, S. Simon, E. Sudano, M. Tadel, Y. Tu, A. Vartak, C. Welke, F. Würthwein, A. Yagil, J. Yoo University of California, San Diego, La Jolla, USA D. Barge, J. Bradmiller-Feld, C. Campagnari, T. Danielson, A. Dishaw, K. Flowers, M. Franco Sevilla, P. Geffert, C. George, F. Golf, L. Gouskos, J. Incandela, C. Justus, N. Mccoll, J. Richman, D. Stuart, W. To, C. West University of California, Santa Barbara, Santa Barbara, USA A. Apresyan, A. Bornheim, J. Bunn, Y. Chen, E. Di Marco, J. Duarte, A. Mott, H.B. Newman, C. Pena, C. Rogan, M. Spiropulu, V. Timciuc, R. Wilkinson, S. Xie, R.Y. Zhu California Institute of Technology, Pasadena, USA V. Azzolini, A. Calamba, T. Ferguson, Y. Iiyama, M. Paulini, J. Russ, H. Vogel, I. Vorobiev Carnegie Mellon University, Pittsburgh, USA J.P. Cumalat, B.R. Drell, W.T. Ford, A. Gaz, E. Luiggi Lopez, U. Nauenberg, J.G. Smith, K. Stenson, K.A. Ulmer, S.R. Wagner University of Colorado at Boulder, Boulder, USA J. Alexander, A. Chatterjee, J. Chu, S. Dittmer, N. Eggert, N. Mirman, G. Nicolas Kaufman, J.R. Patterson, A. Ryd, E. Salvati, L. Skinnari, W. Sun, W.D. Teo, J. Thom, J. Thompson, J. Tucker, Y. Weng, L. Winstrom, P. Wittich Cornell University, Ithaca, USA D. Winn Fairfield University, Fairfield, USA S. Abdullin, M. Albrow, J. Anderson, G. Apollinari, L.A.T. Bauerdick, A. Beretvas, J. Berryhill, P.C. Bhat, K. Burkett, J.N. Butler, H.W.K. Cheung, F. Chlebana, S. Cihangir, V.D. Elvira, I. Fisk, J. Freeman, Y. Gao, E. Gottschalk, L. Gray, D. Green, S. Grünendahl, O. Gutsche, J. Hanlon, D. Hare, R.M. Harris, J. Hirschauer, B. Hooberman, S. Jindariani, M. Johnson, U. Joshi, K. Kaadze, B. Klima, B. Kreis, S. Kwan, J. Linacre, D. Lincoln, R. Lipton, T. Liu, J. Lykken, K. Maeshima, J.M. Marraffino, V.I. Martinez Outschoorn, S. Maruyama, D. Mason, P. McBride, K. Mishra, S. Mrenna, Y. Musienko 31, S. Nahn, C. Newman-Holmes, V. O’Dell, O. Prokofyev, E. Sexton-Kennedy, S. Sharma, A. Soha, W.J. Spalding, L. Spiegel, L. Taylor, S. Tkaczyk, N.V. Tran, L. Uplegger, E.W. Vaandering, R. Vidal, A. Whitbeck, J. Whitmore, F. Yang Fermi National Accelerator Laboratory, Batavia, USA D. Acosta, P. Avery, D. Bourilkov, M. Carver, T. Cheng, D. Curry, S. Das, M. De Gruttola, G.P. Di Giovanni, R.D. Field, M. Fisher, I.K. Furic, J. Hugon, J. Konigsberg, A. Korytov, T. Kypreos, J.F. Low, K. Matchev, P. Milenovic 50, G. Mitselmakher, L. Muniz, A. Rinkevicius, L. Shchutska, N. Skhirtladze, M. Snowball, J. Yelton, M. Zakaria University of Florida, Gainesville, USA CMS Collaboration / Physics Letters B 740 (2015) 83–104 101 S. Hewamanage, S. Linn, P. Markowitz, G. Martinez, J.L. Rodriguez Florida International University, Miami, USA T. Adams, A. Askew, J. Bochenek, B. Diamond, J. Haas, S. Hagopian, V. Hagopian, K.F. Johnson, H. Prosper, V. Veeraraghavan, M. Weinberg Florida State University, Tallahassee, USA M.M. Baarmand, M. Hohlmann, H. Kalakhety, F. Yumiceva Florida Institute of Technology, Melbourne, USA M.R. Adams, L. Apanasevich, V.E. Bazterra, D. Berry, R.R. Betts, I. Bucinskaite, R. Cavanaugh, O. Evdokimov, L. Gauthier, C.E. Gerber, D.J. Hofman, S. Khalatyan, P. Kurt, D.H. Moon, C. O’Brien, C. Silkworth, P. Turner, N. Varelas University of Illinois at Chicago (UIC), Chicago, USA E.A. Albayrak 47, B. Bilki 51, W. Clarida, K. Dilsiz, F. Duru, M. Haytmyradov, J.-P. Merlo, H. Mermerkaya 52, A. Mestvirishvili, A. Moeller, J. Nachtman, H. Ogul, Y. Onel, F. Ozok 47, A. Penzo, R. Rahmat, S. Sen, P. Tan, E. Tiras, J. Wetzel, T. Yetkin 53, K. Yi The University of Iowa, Iowa City, USA B.A. Barnett, B. Blumenfeld, S. Bolognesi, D. Fehling, A.V. Gritsan, P. Maksimovic, C. Martin, M. Swartz Johns Hopkins University, Baltimore, USA P. Baringer, A. Bean, G. Benelli, C. Bruner, J. Gray, R.P. Kenny III, M. Malek, M. Murray, D. Noonan, S. Sanders, J. Sekaric, R. Stringer, Q. Wang, J.S. Wood The University of Kansas, Lawrence, USA A.F. Barfuss, I. Chakaberia, A. Ivanov, S. Khalil, M. Makouski, Y. Maravin, L.K. Saini, S. Shrestha, I. Svintradze Kansas State University, Manhattan, USA J. Gronberg, D. Lange, F. Rebassoo, D. Wright Lawrence Livermore National Laboratory, Livermore, USA A. Baden, A. Belloni, B. Calvert, S.C. Eno, J.A. Gomez, N.J. Hadley, R.G. Kellogg, T. Kolberg, Y. Lu, M. Marionneau, A.C. Mignerey, K. Pedro, A. Skuja, M.B. Tonjes, S.C. Tonwar University of Maryland, College Park, USA A. Apyan, R. Barbieri, G. Bauer, W. Busza, I.A. Cali, M. Chan, L. Di Matteo, V. Dutta, G. Gomez Ceballos, M. Goncharov, D. Gulhan, M. Klute, Y.S. Lai, Y.-J. Lee, A. Levin, P.D. Luckey, T. Ma, C. Paus, D. Ralph, C. Roland, G. Roland, G.S.F. Stephans, F. Stöckli, K. Sumorok, D. Velicanu, J. Veverka, B. Wyslouch, M. Yang, M. Zanetti, V. Zhukova Massachusetts Institute of Technology, Cambridge, USA B. Dahmes, A. Gude, S.C. Kao, K. Klapoetke, Y. Kubota, J. Mans, N. Pastika, R. Rusack, A. Singovsky, N. Tambe, J. Turkewitz University of Minnesota, Minneapolis, USA J.G. Acosta, S. Oliveros University of Mississippi, Oxford, USA 102 CMS Collaboration / Physics Letters B 740 (2015) 83–104 E. Avdeeva, K. Bloom, S. Bose, D.R. Claes, A. Dominguez, R. Gonzalez Suarez, J. Keller, D. Knowlton, I. Kravchenko, J. Lazo-Flores, S. Malik, F. Meier, G.R. Snow University of Nebraska–Lincoln, Lincoln, USA J. Dolen, A. Godshalk, I. Iashvili, A. Kharchilava, A. Kumar, S. Rappoccio State University of New York at Buffalo, Buffalo, USA G. Alverson, E. Barberis, D. Baumgartel, M. Chasco, J. Haley, A. Massironi, D.M. Morse, D. Nash, T. Orimoto, D. Trocino, R.J. Wang, D. Wood, J. Zhang Northeastern University, Boston, USA K.A. Hahn, A. Kubik, N. Mucia, N. Odell, B. Pollack, A. Pozdnyakov, M. Schmitt, S. Stoynev, K. Sung, M. Velasco, S. Won Northwestern University, Evanston, USA A. Brinkerhoff, K.M. Chan, A. Drozdetskiy, M. Hildreth, C. Jessop, D.J. Karmgard, N. Kellams, K. Lannon, W. Luo, S. Lynch, N. Marinelli, T. Pearson, M. Planer, R. Ruchti, N. Valls, M. Wayne, M. Wolf, A. Woodard University of Notre Dame, Notre Dame, USA L. Antonelli, J. Brinson, B. Bylsma, L.S. Durkin, S. Flowers, C. Hill, R. Hughes, K. Kotov, T.Y. Ling, D. Puigh, M. Rodenburg, G. Smith, C. Vuosalo, B.L. Winer, H. Wolfe, H.W. Wulsin The Ohio State University, Columbus, USA O. Driga, P. Elmer, P. Hebda, A. Hunt, S.A. Koay, P. Lujan, D. Marlow, T. Medvedeva, M. Mooney, J. Olsen, P. Piroué, X. Quan, H. Saka, D. Stickland 2, C. Tully, J.S. Werner, S.C. Zenz, A. Zuranski Princeton University, Princeton, USA E. Brownson, H. Mendez, J.E. Ramirez Vargas University of Puerto Rico, Mayaguez, USA E. Alagoz, V.E. Barnes, D. Benedetti, G. Bolla, D. Bortoletto, M. De Mattia, Z. Hu, M.K. Jha, M. Jones, K. Jung, M. Kress, N. Leonardo, D. Lopes Pegna, V. Maroussov, P. Merkel, D.H. Miller, N. Neumeister, B.C. Radburn-Smith, X. Shi, I. Shipsey, D. Silvers, A. Svyatkovskiy, F. Wang, W. Xie, L. Xu, H.D. Yoo, J. Zablocki, Y. Zheng Purdue University, West Lafayette, USA N. Parashar, J. Stupak Purdue University Calumet, Hammond, USA A. Adair, B. Akgun, K.M. Ecklund, F.J.M. Geurts, W. Li, B. Michlin, B.P. Padley, R. Redjimi, J. Roberts, J. Zabel Rice University, Houston, USA B. Betchart, A. Bodek, R. Covarelli, P. de Barbaro, R. Demina, Y. Eshaq, T. Ferbel, A. Garcia-Bellido, P. Goldenzweig, J. Han, A. Harel, A. Khukhunaishvili, D.C. Miner, G. Petrillo, D. Vishnevskiy University of Rochester, Rochester, USA R. Ciesielski, L. Demortier, K. Goulianos, G. Lungu, C. Mesropian The Rockefeller University, New York, USA CMS Collaboration / Physics Letters B 740 (2015) 83–104 103 S. Arora, A. Barker, J.P. Chou, C. Contreras-Campana, E. Contreras-Campana, D. Duggan, D. Ferencek, Y. Gershtein, R. Gray, E. Halkiadakis, D. Hidas, A. Lath, S. Panwalkar, M. Park, R. Patel, V. Rekovic, S. Salur, S. Schnetzer, C. Seitz, S. Somalwar, R. Stone, S. Thomas, P. Thomassen, M. Walker Rutgers, The State University of New Jersey, Piscataway, USA K. Rose, S. Spanier, A. York University of Tennessee, Knoxville, USA O. Bouhali 54, R. Eusebi, W. Flanagan, J. Gilmore, T. Kamon 55, V. Khotilovich, V. Krutelyov, R. Montalvo, I. Osipenkov, Y. Pakhotin, A. Perloff, J. Roe, A. Rose, A. Safonov, T. Sakuma, I. Suarez, A. Tatarinov Texas A&M University, College Station, USA N. Akchurin, C. Cowden, J. Damgov, C. Dragoiu, P.R. Dudero, J. Faulkner, K. Kovitanggoon, S. Kunori, S.W. Lee, T. Libeiro, I. Volobouev Texas Tech University, Lubbock, USA E. Appelt, A.G. Delannoy, S. Greene, A. Gurrola, W. Johns, C. Maguire, Y. Mao, A. Melo, M. Sharma, P. Sheldon, B. Snook, S. Tuo, J. Velkovska Vanderbilt University, Nashville, USA M.W. Arenton, S. Boutle, B. Cox, B. Francis, J. Goodell, R. Hirosky, A. Ledovskoy, H. Li, C. Lin, C. Neu, J. Wood University of Virginia, Charlottesville, USA R. Harr, P.E. Karchin, C. Kottachchi Kankanamge Don, P. Lamichhane, J. Sturdy Wayne State University, Detroit, USA D.A. Belknap, D. Carlsmith, M. Cepeda, S. Dasu, S. Duric, E. Friis, R. Hall-Wilton, M. Herndon, A. Hervé, P. Klabbers, A. Lanaro, C. Lazaridis, A. Levine, R. Loveless, A. Mohapatra, I. Ojalvo, T. Perry, G.A. Pierro, G. Polese, I. Ross, T. Sarangi, A. Savin, W.H. Smith, N. Woods University of Wisconsin, Madison, USA † Deceased. 1 Also at Vienna University of Technology, Vienna, Austria. 2 Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland. 3 Also at Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Université de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France. 4 Also at National Institute of Chemical Physics and Biophysics, Tallinn, Estonia. 5 Also at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia. 6 Also at Universidade Estadual de Campinas, Campinas, Brazil. 7 Also at California Institute of Technology, Pasadena, USA. 8 Also at Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3–CNRS, Palaiseau, France. 9 Also at Joint Institute for Nuclear Research, Dubna, Russia. 10 Also at Suez University, Suez, Egypt. 11 Also at British University in Egypt, Cairo, Egypt. 12 Also at Fayoum University, El-Fayoum, Egypt. 13 Now at Ain Shams University, Cairo, Egypt. 14 Also at Université de Haute Alsace, Mulhouse, France. 15 Also at Brandenburg University of Technology, Cottbus, Germany. 16 Also at The University of Kansas, Lawrence, USA. 17 Also at Institute of Nuclear Research ATOMKI, Debrecen, Hungary. 18 Also at Eötvös Loránd University, Budapest, Hungary. 19 Also at University of Debrecen, Debrecen, Hungary. 20 Also at University of Visva-Bharati, Santiniketan, India. 21 Now at King Abdulaziz University, Jeddah, Saudi Arabia. 22 Also at University of Ruhuna, Matara, Sri Lanka. 23 Also at Isfahan University of Technology, Isfahan, Iran. 24 Also at Sharif University of Technology, Tehran, Iran. 25 Also at Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran. 104 CMS Collaboration / Physics Letters B 740 (2015) 83–104 26 Also at Laboratori Nazionali di Legnaro dell’INFN, Legnaro, Italy. 27 Also at Università degli Studi di Siena, Siena, Italy. 28 Also at Centre National de la Recherche Scientifique (CNRS) – IN2P3, Paris, France. 29 Also at Purdue University, West Lafayette, USA. 30 Also at Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Mexico. 31 Also at Institute for Nuclear Research, Moscow, Russia. 32 Also at St. Petersburg State Polytechnical University, St. Petersburg, Russia. 33 Also at Faculty of Physics, University of Belgrade, Belgrade, Serbia. 34 Also at Facoltà Ingegneria, Università di Roma, Roma, Italy. 35 Also at Scuola Normale e Sezione dell’INFN, Pisa, Italy. 36 Also at University of Athens, Athens, Greece. 37 Also at Paul Scherrer Institut, Villigen, Switzerland. 38 Also at Institute for Theoretical and Experimental Physics, Moscow, Russia. 39 Also at Albert Einstein Center for Fundamental Physics, Bern, Switzerland. 40 Also at Gaziosmanpasa University, Tokat, Turkey. 41 Also at Adiyaman University, Adiyaman, Turkey. 42 Also at Cag University, Mersin, Turkey. 43 Also at Mersin University, Mersin, Turkey. 44 Also at Izmir Institute of Technology, Izmir, Turkey. 45 Also at Ozyegin University, Istanbul, Turkey. 46 Also at Kafkas University, Kars, Turkey. 47 Also at Mimar Sinan University, Istanbul, Istanbul, Turkey. 48 Also at Rutherford Appleton Laboratory, Didcot, United Kingdom. 49 Also at School of Physics and Astronomy, University of Southampton, Southampton, United Kingdom. 50 Also at University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia. 51 Also at Argonne National Laboratory, Argonne, USA. 52 Also at Erzincan University, Erzincan, Turkey. 53 Also at Yildiz Technical University, Istanbul, Turkey. 54 Also at Texas A&M University at Qatar, Doha, Qatar. 55 Also at Kyungpook National University, Daegu, Republic of Korea. Search for new resonances decaying via WZ to leptons in proton-proton collisions at √s=8 TeV 1 Introduction 2 The CMS detector 3 Event simulation 4 Object reconstruction and event selection 5 Systematic uncertainties 6 Results 7 Summary Acknowledgements References CMS Collaboration