Study of Z Boson Production in PbPb Collisions at
ffiffiffiffiffiffiffiffiffi

sNN
p ¼ 2:76 TeV

S. Chatrchyan et al.*

(CMS Collaboration)
(Received 1 March 2011; published 24 May 2011)

A search for Z bosons in the �þ�� decay channel has been performed in PbPb collisions at
ffiffiffiffiffiffiffiffi

sNN
p ¼

2:76 TeV with the CMS detector at the LHC, in a 7:2 �b�1 data sample. The number of opposite-sign

muon pairs observed in the 60–120 GeV=c2 invariant mass range is 39, corresponding to a yield per unit

of rapidity (y) and per minimum bias event of ½33:8� 5:5ðstatÞ � 4:4ðsystÞ� � 10�8, in the jyj< 2:0

range. Rapidity, transverse momentum, and centrality dependencies are also measured. The results agree

with next-to-leading order QCD calculations, scaled by the number of incoherent nucleon-nucleon

collisions.

DOI: 10.1103/PhysRevLett.106.212301 PACS numbers: 25.75.Cj, 12.38.Bx, 14.70.Hp

The hot and dense matter produced in heavy-ion colli-
sions, often referred to as the quark-gluon plasma (QGP),
can be studied in various ways. One approach is to compare
measurements made in heavy-ion (AA) collisions to those
in proton-proton (pp) and proton- (or deuteron-)nucleus
collisions. Another way is to compare in the same AA
sample the yields of particles that are modified by the
QGP to those of unmodified reference particles. At the
Relativistic Heavy Ion Collider (RHIC), direct photons
play the reference role [1], although their measurement is
complicated by copious background from �0 and other
decays, and by the existence of a parton fragmentation
component which is potentially modified by the medium
[2]. At the Large Hadron Collider (LHC) energies, a new
and cleaner reference becomes available: the Z boson,
decaying into leptons [3,4].

Electroweak boson production is an important bench-
mark process at hadron colliders. At 7 TeV center-of-mass
energy, measurements in pp collisions at the LHC [5,6] are
well described by calculations based on higher-order per-
turbative quantum chromodynamics (pQCD), using recent
parton distribution functions (PDFs). In AA collisions, Z
boson production can be affected by various initial-state
effects, though predictions indicate that these contributions
are rather small [3,7–10]. First, the mix of protons and
neutrons in AA collisions (the so-called isospin effect) is
estimated to modify the Z yield by less than 3% compared
to pp collisions [9]. Second, energy loss and multiple
scattering of the initial partons can also alter the Z produc-
tion, by about 3% [10]. The PDFs however are modified
in nuclei and a depletion (shadowing) is expected for Z
bosons at the LHC, modifying their yield by as much as

20% [9]. Precise measurements of Z production in heavy-
ion collisions can therefore help to constrain nuclear PDFs.
Once produced, Z bosons decay within the medium,

with a lifetime of 0:1 fm=c. Their leptonic decays are of
particular interest since leptons lose negligible energy in
the produced medium regardless of its nature (partonic or
hadronic) and properties [4]. Dileptons from Z bosons can
thus serve as a reference to the processes expected to be
heavily modified in the QGP, such as quarkonia produc-
tion, or the production of an opposite-side jet in Zþ jet
processes [3,11]. The Z bosons are therefore ideally suited
to serve as a standard candle of the initial state in PbPb
collisions at the LHC energies.
During the first PbPb LHC run at the end of 2010,

at a center-of-mass energy per nucleon pair of
ffiffiffiffiffiffiffiffi

sNN
p ¼

2:76 TeV, Z bosons were observed by the Compact Muon
Solenoid (CMS) experiment. The measurement reported in
this Letter is performed with a 55� 106 minimum bias
(MB) event sample, corresponding to an integrated lumi-
nosity of 7:2 �b�1.
A detailed description of the CMS detector can be found

in [12]. Its central feature is a superconducting solenoid of
6 m internal diameter, providing a magnetic field of 3.8 T.
Within the field volume are the silicon pixel and strip
tracker, the crystal electromagnetic calorimeter, and the
brass or scintillator hadron calorimeter. Muons are mea-
sured in gas-ionization detectors embedded in the steel
return yoke. In addition, CMS has extensive forward calo-
rimetry, in particular, two steel or quartz-fiber Čerenkov,
hadron forward (HF) calorimeters, which cover the pseu-
dorapidity range 2:9< j�j< 5:2.
In this analysis, Z bosons are measured through their

dimuon decays. The silicon pixel and strip tracker mea-
sures charged particle trajectories in the range j�j< 2:5. It
consists of 66 M pixel and 10 M strip detector channels. It
provides a distance-to-vertex resolution of �15 �m in the
transverse plane. Muons are detected in the j�j< 2:4
range, with detection planes based on three technologies:
drift tubes, cathode strip chambers, and resistive plate
chambers. A matching of the muons to the tracks measured

*Full author list given at the end of the article.

Published by the American Physical Society under the terms of
the Creative Commons Attribution 3.0 License. Further distri-
bution of this work must maintain attribution to the author(s) and
the published article’s title, journal citation, and DOI.

PRL 106, 212301 (2011) P HY S I CA L R EV I EW LE T T E R S
week ending
27 MAY 2011

0031-9007=11=106(21)=212301(14) 212301-1 � 2011 CERN, for the CMS Collaboration

http://dx.doi.org/10.1103/PhysRevLett.106.212301
http://creativecommons.org/licenses/by/3.0/


in the silicon tracker results in a pT resolution between 1%
and 2%, for pT values up to 100 GeV=c.

The centrality of AA collisions, i.e., the geometrical
overlap of the incoming nuclei, is related to the energy
released in the collisions. In CMS, centrality is defined as
percentiles of the distribution of the energy deposited in the
HFs [13,14]. The centrality classes used in this analysis are
30%–100%, 10%–30%, and 0%–10% (most central), or-
dered from the lowest to the highest HF energy deposit.

Events are preselected if they contain a reconstructed
primary vertex made of at least two tracks, and an offline
coincidence of both of the HFs with a total deposited
energy of at least 9 GeV. These criteria reduce contribu-
tions from single-beam interactions with the environment
(e.g., beam-gas and beam halo collisions with the beam
pipe), ultraperipheral electromagnetic collisions, and
cosmic-ray muons. The acceptance of this selection is
(97� 3)% of the hadronic inelastic cross section [13].

The events are also selected by the two-level trigger of
CMS. At the first hardware level, two muon candidates in
the muon detectors are required. At the software-based
higher level, two reconstructed tracks in the muon detec-
tors are required, each with a pT of at least 3 GeV=c. In
order to study the dimuon trigger efficiency, events are
also collected with a single-muon trigger, requiring pT >
20 GeV=c. For Z bosons, the trigger efficiency is estimated
to be ’ 94%.

Muon offline reconstruction is seeded with ’ 99% effi-
ciency by tracks in the muon detectors, called stand-alone
muons. These tracks are then matched to tracks recon-
structed in the silicon tracker by means of an algorithm
optimized for the heavy-ion environment [14,15]. For a
muon from Z decays the tracking efficiency is ’ 85%, less
than in the pp case, as the track reconstruction requires
more pixel hits to lower the number of combinations, due
to the high multiplicity. Global fits of the muon and tracker
tracks, called global muons, are used to obtain the results
presented in this Letter.

Background muons from cosmic rays and heavy-quark
semileptonic decays are rejected by requiring a transverse
(longitudinal) impact parameter of less than 0.3 (1.5) mm
from the measured vertex. Loose criteria applied on the
reconstructed muons result in the dimuon mass spectrum
shown in Fig. 1. No muon isolation criteria are applied, as
they are expected to have reduced efficiency in the high
particle density of the PbPb environment. The fraction of Z
decays removed by the applied selection criteria is esti-
mated to be ’ 2:6%. A conservative upper limit of 4% for
the residual background is estimated by extrapolations of
various shapes from the low mass region, and no correction
is applied. Thirty-nine Z candidates are observed in the
mass interval 60–120 GeV=c2. Their distribution is con-
sistent with the one from pp data at 7 TeV [6], scaled down
to 39 counts and limited to the 60–120 GeV=c2 mass range
as displayed by the histogram in Fig. 1.

Muon trigger, reconstruction, and selection efficiencies,
as well as acceptance, are estimated using the PYTHIA 6.424
simulation [16] with CTEQ6L PDFs [17] and full GEANT4
[18] detector simulation. To take into account the effect of
the higher PbPb underlying-event activity, simulated Z
decays are embedded in measured PbPb events at the level
of detector hits and with generated vertices matched to the
measured ones. These events were processed through the
trigger emulation and event reconstruction chain. Track
characteristics, such as the number of hits and the �2 of
the track fit, have similar distributions in data and simula-
tion. The detector acceptance �, defined as the fraction of
Z bosons produced at rapidity jyj< 2:0 that decay into
muons with j�j< 2:4 and pT > 10 GeV=c, is estimated to
be 78%. Within this acceptance, the overall trigger, recon-
struction, and identification efficiency " averages to 67%,
and varies by less than 10% as a function of centrality.
The individual components of this efficiency are also

estimated with a data-driven technique, called tag-and-
probe, similar to the one used for the corresponding pp
measurement [6]. It consists in counting the Z candidates
with and without applying the probed selection on one of
the muons: (1) the stand-alone muon reconstruction effi-
ciency is probed with tracker tracks; (2) the silicon tracker
reconstruction efficiency is probed with stand-alone
muons; (3) the trigger efficiency is probed by testing the
trigger response to global muons from a sample triggered
by a single-muon requirement. The last is also checked
with high-quality reconstructed muons fromMB events. In
all cases, these data-driven efficiencies agree with those
derived from simulation within the statistical uncertainties.
The total systematic uncertainty on the Z yield is esti-

mated to be 13% by summing in quadrature the following
contributions. The largest one is associated with the
tracking efficiency and taken as the 9.8% precision of the
above-mentioned data-driven efficiency determination.
Similarly, the uncertainty associated with the dimuon

)2Dimuon mass (GeV/c

30 40 50 60 70 80 90 100 110 120

)2
E

ve
nt

s/
(2

 G
eV

/c

0

5

10

15

Opposite-sign

Same-sign
-1CMS pp 7 TeV 2.9 pb

 = 2.76 TeVNNsCMS PbPb 
-1

bµ Ldt = 7.2 ∫
  < 2.4µη > 10 GeV/c, µ

T
p

)2Dimuon mass (GeV/c

30 40 50 60 70 80 90 100 110 120

)2
E

ve
nt

s/
(2

 G
eV

/c

0

5

10

15

FIG. 1 (color online). Dimuon invariant mass spectra. Full
squares are opposite-sign dimuons, while the empty circle shows
a unique like-sign dimuon candidate. The histogram shows the
corresponding distribution measured in pp collisions at 7 TeV
within 60–120 GeV=c2, scaled to the 39 PbPb candidates.

PRL 106, 212301 (2011) P HY S I CA L R EV I EW LE T T E R S
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212301-2



trigger is 4.5%. The 4% maximum contribution from un-
subtracted background is taken as a systematic uncertainty.
The uncertainty associated with the muon-pair selection is
considered to be equal to the 2.6% loss of events. The MB
trigger efficiency is known at the 3% level. The uncertainty
coming from the acceptance correction is estimated
to be less than 3%, by varying the underlying generated
kinematics (y, pT) beyond reasonable modifications.
Other systematic uncertainties are estimated to sum to
less than 1.5%.

The yield of Z ! �þ�� decays per MB event is defined
as dN=dyðjyj< 2:0Þ ¼ NZ=ð�"NMB�yÞ, where NZ ¼ 39
is the number of dimuons counted in the mass window of
60–120 GeV=c2, NMB ¼ 55� 106 is the number of corre-
spondingMB events, corrected for trigger efficiency,� and
" are the acceptance and overall efficiency, and �y ¼ 4:0
is the rapidity bin width. We find dN=dyðjyj< 2:0Þ ¼
ð33:8� 5:5� 4:4Þ � 10�8, where the first uncertainty is
statistical and the second systematic. The analysis de-
scribed above is repeated after subdividing the data into
three bins for each of the following variables: event cen-
trality and Z boson y and pT . The total systematic uncer-
tainty does not vary significantly with these variables and is
considered to be constant and dominantly uncorrelated.

In the absence of in-medium modifications, the yield of
perturbative processes such as the Z boson production is
supposed to scale with the number of incoherent nucleon-
nucleon binary collisions [19]. In order to compare the
PbPb measured yields to available pp cross-section calcu-
lations, a scaling factor TAB is necessary. This nuclear
overlap function is equal to the number of elementary
nucleon-nucleon binary collisions divided by the elemen-
tary NN cross section, and can be interpreted as the NN
equivalent integrated luminosity per AA collision, at a
given centrality. In units ofmb�1, the average TAB amounts
to 1:45� 0:18, 11:6� 0:7, and 23:2� 1:0, for the central-
ity ranges 30%–100%, 10%–30%, and 0%–10%, respec-
tively, and 5:66� 0:35 for MB events. These numbers are
computed with a Glauber model calculation [19], using the
same parameters as in [13]. The quoted uncertainties are
derived by varying within uncertainties the Glauber pa-
rameters and the MB trigger and selection efficiency.

The full circles in Fig. 2(a) show the centrality depen-
dence of the Z yield divided by TAB, while the open square
is for MB events. The variable used on the abscissa is the
average number of participating nucleons Npart corre-

sponding to the selected centrality intervals, computed in
the same Glauber model. No centrality dependence of the
binary-scaled Z yields is observed in data. A similar result
was recently published by the ATLAS collaboration [20].

The normalized yields ðdN=dyÞ=TAB are compared to
various calculations: (1) using the nucleon CT10 and
modified nuclear EPS09 PDFs [9,21], (2) using
MSTW08 PDFs [22] and modeling incoming-parton en-
ergy loss [11], and (3) provided by the POWHEG [23]

partN
0 50 100 150 200 250 300 350 400

 (
pb

)
A

B
dN

/d
y 

(|
y|

<
2.

0)
 / 

T

0

10

20

30

40

50

60

70

80

90

100

POWHEG + PYTHIA 6.4
Paukkunen et al., CT10+isospin

Paukkunen et al., idem+EPS09
Neufeld et al., MSTW+isospin

Neufeld et al., idem+eloss

a)  = 2.76 TeVNNs at -1bµCMS PbPb 7.2 

[30-100]%

[10-30]%

[0-10]%[0-100]%

Rapidity

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

dN
/d

y

0

10

20

30

40

50

60

CMS
POWHEG + PYTHIA 6.4
Paukkunen et al., CT10+isospin

Paukkunen et al., idem+EPS09
Neufeld et al., MSTW+isospin

Neufeld et al., idem+eloss

b)  = 2.76 TeVNNs at -1bµCMS PbPb 7.2 

-8x10

Transverse momentum (GeV/c)
0 5 10 15 20 25 30 35

-1
 (

G
eV

/c
)

T
N

/d
yd

p
2

d

0

0.5

1

1.5

2

2.5

3

CMS, |y|<2.0

POWHEG + PYTHIA 6.4

c)  = 2.76 TeVNNs at -1bµCMS PbPb 7.2 

-8x10

FIG. 2 (color online). The yields of Z ! �� per event:
(a) dN=dy divided by the expected nuclear overlap function
TAB and as a function of event centrality parametrized as the
number of participating nucleons Npart, (b) dN=dy versus the Z

boson y, (c) d2N=dydpT versus the Z boson pT . Data points
are located horizontally at average values measured within
a given bin. Vertical lines (bands) correspond to statistical
(systematic) uncertainties. Theoretical predictions are computed
within the same bins as the data, and are described in
the text.

PRL 106, 212301 (2011) P HY S I CA L R EV I EW LE T T E R S
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212301-3



generator interfaced with the PYTHIA parton-shower gen-
erator and using CTEQ6.6 PDFs [17]. Only a marginal
centrality dependence is predicted: the inhomogeneous
(i.e., depending on the radial position in nuclei) shadowing
is predicted to have negligible impact [7] and the energy-
loss prediction drops by 3% from peripheral to central
collisions [11].

Figures 2(b) and 2(c) show the differential yields,
dN=dy and d2N=dydpT , as a function of the Z boson y
and pT . They are compared to the same theoretical calcu-
lations as used for the centrality distribution (when avail-
able) multiplied by the minimum bias TAB value. In all
bins, no significant deviations from binary-collision scal-
ing are observed.

Nuclear modification factors, RAA¼dN=ðTAB�d�ppÞ,
are computed from the AAmeasured yields dN, the nuclear
overlap function TAB, and the pp ! Z cross sections d�pp

given by the POWHEG calculation (solid lines on Fig. 2, e.g.,
d�pp=dy ¼ 59:6 pb in jyj< 2:0). The RAA systematic un-

certainty includes TAB uncertainties, but no uncertainty is
assigned to the theoretical pp cross section. All RAA values
are found compatible with unity. They are reported in
Table I, together with the number of observed Z bosons
and their yield per event.

In conclusion, the Z boson yield in PbPb collisions at
ffiffiffiffiffiffiffiffi

sNN
p ¼ 2:76 TeV has been measured inclusively and as a

function of rapidity, transverse momentum, and centrality.
Within uncertainties, no modification is observed with
respect to theoretical next-to-leading order perturbative
quantum chromodynamics proton-proton cross sections
scaled by the number of elementary nucleon-nucleon
collisions. This measurement confirms the validity of
the Glauber scaling for perturbative cross sections in
nucleus-nucleus collisions at the LHC and establishes the

feasibility of carrying out detailed Z physics studies in
heavy-ion collisions with the CMS detector. With upcom-
ing PbPb collisions at higher luminosity, the Z boson
promises to be a powerful reference tool for final-state
heavy-ion related signatures as well as providing a means
to study the modifications of the parton distribution
functions.
We thank Bryon Neufeld, Hannu Paukkunen, Carlos

Salgado, Ivan Vitev, and Ramona Vogt for fruitful theoreti-
cal inputs on the nuclear effects involved in Z production.
We wish to congratulate our colleagues in the CERN
accelerator departments for the excellent performance of
the LHC machine in 2010. We thank the technical and
administrative staff at CERN and other CMS institutes,
and acknowledge support from FMSR (Austria); FNRS
and FWO (Belgium); CNPq, CAPES, FAPERJ, and
FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST,
and NSFC (China); COLCIENCIAS (Colombia); MSES
(Croatia); RPF (Cyprus); Academy of Sciences and NICPB
(Estonia); Academy of Finland, ME, and HIP (Finland);
CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF
(Germany); GSRT (Greece); OTKA andNKTH (Hungary);
DAE and DST (India); IPM (Iran); SFI (Ireland); INFN
(Italy); NRF and WCU (Korea); LAS (Lithuania);
CINVESTAV, CONACYT, SEP, and UASLP-FAI
(Mexico); PAEC (Pakistan); SCSR (Poland); FCT
(Portugal); JINR (Armenia, Belarus, Georgia, Ukraine,
Uzbekistan); MST and MAE (Russia); MSTD (Serbia);
MICINN and CPAN (Spain); Swiss Funding Agencies
(Switzerland); NSC (Taipei); TUBITAK and TAEK
(Turkey); STFC (United Kingdom); DOE and NSF (USA).

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modification factor RAA derived by using a POWHEG pp refer-
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jyj NZ dN=dy (10�8) RAA

[0, 2.0] 39 33:8� 5:5� 4:4 1:00� 0:16� 0:14
[0, 0.5] 13 38:1� 10:7� 5:0 1:03� 0:29� 0:15
[0.5, 1.0] 12 35:6� 10:4� 4:6 0:98� 0:29� 0:14
[1.0, 2.0] 14 30:0� 8:1� 3:9 0:97� 0:26� 0:14

pTðGeV=cÞ NZ d2N=dydpT (10�8) RAA

[0, 6] 11 1:65� 0:50� 0:22 0:84� 0:26� 0:12
[6, 12] 15 2:05� 0:54� 0:27 1:32� 0:34� 0:19
[12, 36] 12 0:44� 0:13� 0:06 1:06� 0:31� 0:15

Centrality NZ dN=dy (10�8) RAA

[30, 100]% 7 7:9� 3:0� 1:0 0:92� 0:35� 0:16
[10, 30]% 14 59:5� 16:0� 7:7 0:86� 0:23� 0:12
[0, 10]% 18 165� 40� 22 1:20� 0:29� 0:16

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S. Chatrchyan,1 V. Khachatryan,1 A.M. Sirunyan,1 A. Tumasyan,1 W. Adam,2 T. Bergauer,2 M. Dragicevic,2 J. Erö,2

C. Fabjan,2 M. Friedl,2 R. Frühwirth,2 V.M. Ghete,2 J. Hammer,2,b S. Hänsel,2 C. Hartl,2 M. Hoch,2 N. Hörmann,2

J. Hrubec,2 M. Jeitler,2 G. Kasieczka,2 W. Kiesenhofer,2 M. Krammer,2 D. Liko,2 I. Mikulec,2 M. Pernicka,2

H. Rohringer,2 R. Schöfbeck,2 J. Strauss,2 F. Teischinger,2 P. Wagner,2 W. Waltenberger,2 G. Walzel,2 E. Widl,2

C.-E. Wulz,2 V. Mossolov,3 N. Shumeiko,3 J. Suarez Gonzalez,3 L. Benucci,4 E. A. De Wolf,4 X. Janssen,4 T. Maes,4

L. Mucibello,4 S. Ochesanu,4 B. Roland,4 R. Rougny,4 M. Selvaggi,4 H. Van Haevermaet,4 P. Van Mechelen,4

N. Van Remortel,4 F. Blekman,5 S. Blyweert,5 J. D’Hondt,5 O. Devroede,5 R. Gonzalez Suarez,5 A. Kalogeropoulos,5

J. Maes,5 M. Maes,5 W. Van Doninck,5 P. Van Mulders,5 G. P. Van Onsem,5 I. Villella,5 O. Charaf,6 B. Clerbaux,6

G. De Lentdecker,6 V. Dero,6 A. P. R. Gay,6 G.H. Hammad,6 T. Hreus,6 P. E. Marage,6 L. Thomas,6 C. Vander Velde,6

P. Vanlaer,6 J. Wickens,6 V. Adler,7 S. Costantini,7 M. Grunewald,7 B. Klein,7 A. Marinov,7 J. Mccartin,7

D. Ryckbosch,7 F. Thyssen,7 M. Tytgat,7 L. Vanelderen,7 P. Verwilligen,7 S. Walsh,7 N. Zaganidis,7 S. Basegmez,8

G. Bruno,8 J. Caudron,8 L. Ceard,8 E. Cortina Gil,8 C. Delaere,8 D. Favart,8 A. Giammanco,8 G. Grégoire,8 J. Hollar,8

V. Lemaitre,8 J. Liao,8 O. Militaru,8 S. Ovyn,8 D. Pagano,8 A. Pin,8 K. Piotrzkowski,8 N. Schul,8 N. Beliy,9

T. Caebergs,9 E. Daubie,9 G.A. Alves,10 D. De Jesus Damiao,10 M. E. Pol,10 M.H.G. Souza,10 W. Carvalho,11

E.M. Da Costa,11 C. De Oliveira Martins,11 S. Fonseca De Souza,11 L. Mundim,11 H. Nogima,11 V. Oguri,11

W. L. Prado Da Silva,11 A. Santoro,11 S.M. Silva Do Amaral,11 A. Sznajder,11 F. Torres Da Silva De Araujo,11

F. A. Dias,12 T. R. Fernandez Perez Tomei,12 E.M. Gregores,12,c C. Lagana,12 F. Marinho,12 P. G. Mercadante,12,c

S. F. Novaes,12 Sandra S. Padula,12 N. Darmenov,13,b L. Dimitrov,13 V. Genchev,13,b P. Iaydjiev,13,b S. Piperov,13

M. Rodozov,13 S. Stoykova,13 G. Sultanov,13 V. Tcholakov,13 R. Trayanov,13 I. Vankov,13 M. Dyulendarova,14

R. Hadjiiska,14 V. Kozhuharov,14 L. Litov,14 E. Marinova,14 M. Mateev,14 B. Pavlov,14 P. Petkov,14 J. G. Bian,15

G.M. Chen,15 H. S. Chen,15 C. H. Jiang,15 D. Liang,15 S. Liang,15 X. Meng,15 J. Tao,15 J. Wang,15 J. Wang,15

X. Wang,15 Z. Wang,15 H. Xiao,15 M. Xu,15 J. Zang,15 Z. Zhang,15 Y. Ban,16 S. Guo,16 Y. Guo,16 W. Li,16 Y. Mao,16

S. J. Qian,16 H. Teng,16 L. Zhang,16 B. Zhu,16 W. Zou,16 A. Cabrera,17 B. Gomez Moreno,17 A. A. Ocampo Rios,17

A. F. Osorio Oliveros,17 J. C. Sanabria,17 N. Godinovic,18 D. Lelas,18 K. Lelas,18 R. Plestina,18,d D. Polic,18

I. Puljak,18 Z. Antunovic,19 M. Dzelalija,19 V. Brigljevic,20 S. Duric,20 K. Kadija,20 S. Morovic,20 A. Attikis,21

M. Galanti,21 J. Mousa,21 C. Nicolaou,21 F. Ptochos,21 P. A. Razis,21 M. Finger,22 M. Finger, Jr.,22 Y. Assran,23,e

S. Khalil,23,f A. Radi,23 A. Hektor,24 M. Kadastik,24 M. Müntel,24 M. Raidal,24 L. Rebane,24 V. Azzolini,25

P. Eerola,25 S. Czellar,26 J. Härkönen,26 V. Karimäki,26 R. Kinnunen,26 M. J. Kortelainen,26 T. Lampén,26

K. Lassila-Perini,26 S. Lehti,26 T. Lindén,26 P. Luukka,26 T. Mäenpää,26 E. Tuominen,26 J. Tuominiemi,26

E. Tuovinen,26 D. Ungaro,26 L. Wendland,26 K. Banzuzi,27 A. Korpela,27 T. Tuuva,27 D. Sillou,28 M. Besancon,29

S. Choudhury,29 M. Dejardin,29 D. Denegri,29 B. Fabbro,29 J. L. Faure,29 F. Ferri,29 S. Ganjour,29 F. X. Gentit,29

A. Givernaud,29 P. Gras,29 G. Hamel de Monchenault,29 P. Jarry,29 E. Locci,29 J. Malcles,29 M. Marionneau,29

L. Millischer,29 J. Rander,29 A. Rosowsky,29 I. Shreyber,29 M. Titov,29 P. Verrecchia,29 S. Baffioni,30 F. Beaudette,30

L. Benhabib,30 L. Bianchini,30 M. Bluj,30,g C. Broutin,30 P. Busson,30 C. Charlot,30 T. Dahms,30 L. Dobrzynski,30

S. Elgammal,30 R. Granier de Cassagnac,30 M. Haguenauer,30 P. Miné,30 C. Mironov,30 C. Ochando,30 P. Paganini,30

D. Sabes,30 R. Salerno,30 Y. Sirois,30 C. Thiebaux,30 B. Wyslouch,30,h A. Zabi,30 J.-L. Agram,31,i J. Andrea,31

D. Bloch,31 D. Bodin,31 J.-M. Brom,31 M. Cardaci,31 E. C. Chabert,31 C. Collard,31 E. Conte,31,i F. Drouhin,31,i

C. Ferro,31 J.-C. Fontaine,31,i D. Gelé,31 U. Goerlach,31 S. Greder,31 P. Juillot,31 M. Karim,31,i A.-C. Le Bihan,31

Y. Mikami,31 P. Van Hove,31 F. Fassi,32 D. Mercier,32 C. Baty,33 S. Beauceron,33 N. Beaupere,33 M. Bedjidian,33

O. Bondu,33 G. Boudoul,33 D. Boumediene,33 H. Brun,33 N. Chanon,33 R. Chierici,33 D. Contardo,33 P. Depasse,33

H. El Mamouni,33 A. Falkiewicz,33 J. Fay,33 S. Gascon,33 B. Ille,33 T. Kurca,33 T. Le Grand,33 M. Lethuillier,33

L. Mirabito,33 S. Perries,33 V. Sordini,33 S. Tosi,33 Y. Tschudi,33 P. Verdier,33 V. Roinishvili,34 D. Lomidze,35

G. Anagnostou,36 M. Edelhoff,36 L. Feld,36 N. Heracleous,36 O. Hindrichs,36 R. Jussen,36 K. Klein,36 J. Merz,36

N. Mohr,36 A. Ostapchuk,36 A. Perieanu,36 F. Raupach,36 J. Sammet,36 S. Schael,36 D. Sprenger,36 H. Weber,36

PRL 106, 212301 (2011) P HY S I CA L R EV I EW LE T T E R S
week ending
27 MAY 2011

212301-5

http://dx.doi.org/10.1088/1126-6708/2002/07/012
http://dx.doi.org/10.1016/S0168-9002(03)01368-8
http://dx.doi.org/10.1016/S0168-9002(03)01368-8
http://dx.doi.org/10.1146/annurev.nucl.57.090506.123020
http://dx.doi.org/10.1146/annurev.nucl.57.090506.123020
http://dx.doi.org/10.1016/j.physletb.2011.02.006
http://dx.doi.org/10.1088/1126-6708/2009/04/065
http://dx.doi.org/10.1088/1126-6708/2009/04/065
http://dx.doi.org/10.1140/epjc/s10052-009-1072-5
http://dx.doi.org/10.1140/epjc/s10052-009-1072-5
http://dx.doi.org/10.1088/1126-6708/2008/07/060
http://dx.doi.org/10.1088/1126-6708/2008/07/060


M.Weber,36 B. Wittmer,36 M. Ata,37 W. Bender,37 M. Erdmann,37 J. Frangenheim,37 T. Hebbeker,37 A. Hinzmann,37

K. Hoepfner,37 C. Hof,37 T. Klimkovich,37 D. Klingebiel,37 P. Kreuzer,37 D. Lanske,37,a C. Magass,37 G. Masetti,37

M. Merschmeyer,37 A. Meyer,37 P. Papacz,37 H. Pieta,37 H. Reithler,37 S. A. Schmitz,37 L. Sonnenschein,37

J. Steggemann,37 D. Teyssier,37 M. Tonutti,37 M. Bontenackels,38 M. Davids,38 M. Duda,38 G. Flügge,38

H. Geenen,38 M. Giffels,38 W. Haj Ahmad,38 D. Heydhausen,38 T. Kress,38 Y. Kuessel,38 A. Linn,38 A. Nowack,38

L. Perchalla,38 O. Pooth,38 J. Rennefeld,38 P. Sauerland,38 A. Stahl,38 M. Thomas,38 D. Tornier,38 M.H. Zoeller,38

M. Aldaya Martin,39 W. Behrenhoff,39 U. Behrens,39 M. Bergholz,39,j K. Borras,39 A. Cakir,39 A. Campbell,39

E. Castro,39 D. Dammann,39 G. Eckerlin,39 D. Eckstein,39 A. Flossdorf,39 G. Flucke,39 A. Geiser,39 J. Hauk,39

H. Jung,39 M. Kasemann,39 I. Katkov,39 P. Katsas,39 C. Kleinwort,39 H. Kluge,39 A. Knutsson,39 M. Krämer,39

D. Krücker,39 E. Kuznetsova,39 W. Lange,39 W. Lohmann,39,j R. Mankel,39 M. Marienfeld,39

I.-A. Melzer-Pellmann,39 A. B. Meyer,39 J. Mnich,39 A. Mussgiller,39 J. Olzem,39 D. Pitzl,39 A. Raspereza,39

A. Raval,39 M. Rosin,39 R. Schmidt,39,j T. Schoerner-Sadenius,39 N. Sen,39 A. Spiridonov,39 M. Stein,39

J. Tomaszewska,39 R. Walsh,39 C. Wissing,39 C. Autermann,40 S. Bobrovskyi,40 J. Draeger,40 H. Enderle,40

U. Gebbert,40 K. Kaschube,40 G. Kaussen,40 J. Lange,40 B. Mura,40 S. Naumann-Emme,40 F. Nowak,40 N. Pietsch,40

C. Sander,40 H. Schettler,40 P. Schleper,40 M. Schröder,40 T. Schum,40 J. Schwandt,40 H. Stadie,40 G. Steinbrück,40

J. Thomsen,40 C. Barth,41 J. Bauer,41 V. Buege,41 T. Chwalek,41 W. De Boer,41 A. Dierlamm,41 G. Dirkes,41

M. Feindt,41 J. Gruschke,41 C. Hackstein,41 F. Hartmann,41 S.M. Heindl,41 M. Heinrich,41 H. Held,41

K. H. Hoffmann,41 S. Honc,41 T. Kuhr,41 D. Martschei,41 S. Mueller,41 Th. Müller,41 M. Niegel,41 O. Oberst,41

A. Oehler,41 J. Ott,41 T. Peiffer,41 D. Piparo,41 G. Quast,41 K. Rabbertz,41 F. Ratnikov,41 N. Ratnikova,41 M. Renz,41

C. Saout,41 A. Scheurer,41 P. Schieferdecker,41 F.-P. Schilling,41 M. Schmanau,41 G. Schott,41 H. J. Simonis,41

F.M. Stober,41 D. Troendle,41 J. Wagner-Kuhr,41 T. Weiler,41 M. Zeise,41 V. Zhukov,41,k E. B. Ziebarth,41

G. Daskalakis,42 T. Geralis,42 K. Karafasoulis,42 S. Kesisoglou,42 A. Kyriakis,42 D. Loukas,42 I. Manolakos,42

A. Markou,42 C. Markou,42 C. Mavrommatis,42 E. Ntomari,42 E. Petrakou,42 L. Gouskos,43 T. J. Mertzimekis,43

A. Panagiotou,43 I. Evangelou,44 C. Foudas,44 P. Kokkas,44 N. Manthos,44 I. Papadopoulos,44 V. Patras,44

F. A. Triantis,44 A. Aranyi,45 G. Bencze,45 L. Boldizsar,45 C. Hajdu,45,b P. Hidas,45 D. Horvath,45,l A. Kapusi,45

K. Krajczar,45,m F. Sikler,45 G. I. Veres,45,m G. Vesztergombi,45,m N. Beni,46 J. Molnar,46 J. Palinkas,46 Z. Szillasi,46

V. Veszpremi,46 P. Raics,47 Z. L. Trocsanyi,47 B. Ujvari,47 S. Bansal,48 S. B. Beri,48 V. Bhatnagar,48 N. Dhingra,48

R. Gupta,48 M. Jindal,48 M. Kaur,48 J.M. Kohli,48 M. Z. Mehta,48 N. Nishu,48 L. K. Saini,48 A. Sharma,48

A. P. Singh,48 J. B. Singh,48 S. P. Singh,48 S. Ahuja,49 S. Bhattacharya,49 B. C. Choudhary,49 P. Gupta,49 S. Jain,49

S. Jain,49 A. Kumar,49 K. Ranjan,49 R. K. Shivpuri,49 R. K. Choudhury,50 D. Dutta,50 S. Kailas,50 V. Kumar,50

A. K. Mohanty,50,b L.M. Pant,50 P. Shukla,50 T. Aziz,51 M. Guchait,51,n A. Gurtu,51 M. Maity,51,o D. Majumder,51

G. Majumder,51 K. Mazumdar,51 G. B. Mohanty,51 A. Saha,51 K. Sudhakar,51 N. Wickramage,51 S. Banerjee,52

S. Dugad,52 N.K. Mondal,52 H. Arfaei,53 H. Bakhshiansohi,53 S.M. Etesami,53 A. Fahim,53 M. Hashemi,53

A. Jafari,53 M. Khakzad,53 A. Mohammadi,53 M. Mohammadi Najafabadi,53 S. Paktinat Mehdiabadi,53

B. Safarzadeh,53 M. Zeinali,53 M. Abbrescia,54a,54b L. Barbone,54a,54b C. Calabria,54a,54b A. Colaleo,54a

D. Creanza,54a,54c N. De Filippis,54a,54c M. De Palma,54a,54b A. Dimitrov,54a L. Fiore,54a G. Iaselli,54a,54c

L. Lusito,54a,54b,b G. Maggi,54a,54c M. Maggi,54a N. Manna,54a,54b B. Marangelli,54a,54b S. My,54a,54c S. Nuzzo,54a,54b

N. Pacifico,54a,54b G.A. Pierro,54a A. Pompili,54a,54b G. Pugliese,54a,54c F. Romano,54a,54c G. Roselli,54a,54b

G. Selvaggi,54a,54b L. Silvestris,54a R. Trentadue,54a S. Tupputi,54a,54b G. Zito,54a G. Abbiendi,55a A. C. Benvenuti,55a

D. Bonacorsi,55a S. Braibant-Giacomelli,55a,55b L. Brigliadori,55a P. Capiluppi,55a,55b A. Castro,55a,55b

F. R. Cavallo,55a M. Cuffiani,55a,55b G.M. Dallavalle,55a F. Fabbri,55a A. Fanfani,55a,55b D. Fasanella,55a

P. Giacomelli,55a M. Giunta,55a S. Marcellini,55a M. Meneghelli,55a,55b A. Montanari,55a F. L. Navarria,55a,55b

F. Odorici,55a A. Perrotta,55a F. Primavera,55a A.M. Rossi,55a,55b T. Rovelli,55a,55b G. Siroli,55a,55b

R. Travaglini,55a,55b S. Albergo,56a,56b G. Cappello,56a,56b M. Chiorboli,56a,56b,b S. Costa,56a,56b A. Tricomi,56a,56b

C. Tuve,56a G. Barbagli,57a V. Ciulli,57a,57b C. Civinini,57a R. D’Alessandro,57a,57b E. Focardi,57a,57b S. Frosali,57a,57b

E. Gallo,57a S. Gonzi,57a,57b P. Lenzi,57a,57b M. Meschini,57a S. Paoletti,57a G. Sguazzoni,57a A. Tropiano,57a,b

L. Benussi,58 S. Bianco,58 S. Colafranceschi,58,p F. Fabbri,58 D. Piccolo,58 P. Fabbricatore,59 R. Musenich,59

A. Benaglia,60a,60b F. De Guio,60a,60b,b L. Di Matteo,60a,60b A. Ghezzi,60a,60b,b M. Malberti,60a,60b S. Malvezzi,60a

A. Martelli,60a,60b A. Massironi,60a,60b D. Menasce,60a L. Moroni,60a M. Paganoni,60a,60b D. Pedrini,60a

S. Ragazzi,60a,60b N. Redaelli,60a S. Sala,60a T. Tabarelli de Fatis,60a,60b V. Tancini,60a,60b S. Buontempo,61a

C.A. Carrillo Montoya,61a N. Cavallo,61a,q A. Cimmino,61a,61b A. De Cosa,61a,61b M. De Gruttola,61a,61b

PRL 106, 212301 (2011) P HY S I CA L R EV I EW LE T T E R S
week ending
27 MAY 2011

212301-6



F. Fabozzi,61a,q A.O.M. Iorio,61a L. Lista,61a M. Merola,61a,61b P. Noli,61a,61b P. Paolucci,61a P. Azzi,62a

N. Bacchetta,62a P. Bellan,62a,62b D. Bisello,62a,62b A. Branca,62a R. Carlin,62a,62b P. Checchia,62a M. De Mattia,62a,62b

T. Dorigo,62a U. Dosselli,62a F. Fanzago,62a F. Gasparini,62a,62b U. Gasparini,62a,62b S. Lacaprara,62a,r

I. Lazzizzera,62a,62c M. Margoni,62a,62b M. Mazzucato,62a A. T. Meneguzzo,62a,62b M. Nespolo,62a L. Perrozzi,62a,b

N. Pozzobon,62a,62b P. Ronchese,62a,62b F. Simonetto,62a,62b E. Torassa,62a M. Tosi,62a,62b S. Vanini,62a,62b

P. Zotto,62a,62b G. Zumerle,62a,62b P. Baesso,63a,63b U. Berzano,63a S. P. Ratti,63a,63b C. Riccardi,63a,63b P. Torre,63a,63b

P. Vitulo,63a,63b C. Viviani,63a,63b M. Biasini,64a,64b G.M. Bilei,64a B. Caponeri,64a,64b L. Fanò,64a,64b

P. Lariccia,64a,64b A. Lucaroni,64a,64b,b G. Mantovani,64a,64b M. Menichelli,64a A. Nappi,64a,64b A. Santocchia,64a,64b

S. Taroni,64a,64b M. Valdata,64a,64b R. Volpe,64a,64b,b P. Azzurri,65a,65c G. Bagliesi,65a J. Bernardini,65a,65b

T. Boccali,65a,b G. Broccolo,65a,65c R. Castaldi,65a R. T. D’Agnolo,65a,65c R. Dell’Orso,65a F. Fiori,65a,65b L. Foà,65a,65c

A. Giassi,65a A. Kraan,65a F. Ligabue,65a,65c T. Lomtadze,65a L. Martini,65a,s A. Messineo,65a,65b F. Palla,65a

F. Palmonari,65a G. Segneri,65a A. T. Serban,65a P. Spagnolo,65a R. Tenchini,65a G. Tonelli,65a,65b,b A. Venturi,65a,b

P. G. Verdini,65a L. Barone,66a,66b F. Cavallari,66a D. Del Re,66a,66b E. Di Marco,66a,66b M. Diemoz,66a D. Franci,66a,66b

M. Grassi,66a E. Longo,66a,66b S. Nourbakhsh,66a G. Organtini,66a,66b A. Palma,66a,66b F. Pandolfi,66a,66b,b

R. Paramatti,66a S. Rahatlou,66a,66b N. Amapane,67a,67b R. Arcidiacono,67a,67c S. Argiro,67a,67b M. Arneodo,67a,67c

C. Biino,67a C. Botta,67a,67b,b N. Cartiglia,67a R. Castello,67a,67b M. Costa,67a,67b N. Demaria,67a A. Graziano,67a,67b,b

C. Mariotti,67a M. Marone,67a,67b S. Maselli,67a E. Migliore,67a,67b G. Mila,67a,67b V. Monaco,67a,67b M.Musich,67a,67b

M.M. Obertino,67a,67c N. Pastrone,67a M. Pelliccioni,67a,67b,b A. Romero,67a,67b M. Ruspa,67a,67c R. Sacchi,67a,67b

V. Sola,67a,67b A. Solano,67a,67b A. Staiano,67a D. Trocino,67a,67b A. Vilela Pereira,67a,67b,b S. Belforte,68a

F. Cossutti,68a G. Della Ricca,68a,68b B. Gobbo,68a D. Montanino,68a,68b A. Penzo,68a S. G. Heo,69 S. K. Nam,69

S. Chang,70 J. Chung,70 D.H. Kim,70 G.N. Kim,70 J. E. Kim,70 D. J. Kong,70 H. Park,70 S. R. Ro,70 D. Son,70

D. C. Son,70 Zero Kim,71 J. Y. Kim,71 S. Song,71 S. Choi,72 B. Hong,72 M. S. Jeong,72 M. Jo,72 H. Kim,72 J. H. Kim,72

T. J. Kim,72 K. S. Lee,72 D. H. Moon,72 S. K. Park,72 H. B. Rhee,72 E. Seo,72 S. Shin,72 K. S. Sim,72 M. Choi,73

S. Kang,73 H. Kim,73 C. Park,73 I. C. Park,73 S. Park,73 G. Ryu,73 Y. Choi,74 Y. K. Choi,74 J. Goh,74 M. S. Kim,74

J. Lee,74 S. Lee,74 H. Seo,74 I. Yu,74 M. J. Bilinskas,75 I. Grigelionis,75 M. Janulis,75 D. Martisiute,75 P. Petrov,75

T. Sabonis,75 H. Castilla-Valdez,76 E. De La Cruz-Burelo,76 R. Lopez-Fernandez,76 A. Sánchez-Hernández,76

L.M. Villasenor-Cendejas,76 S. Carrillo Moreno,77 F. Vazquez Valencia,77 H.A. Salazar Ibarguen,78

E. Casimiro Linares,79 A. Morelos Pineda,79 M.A. Reyes-Santos,79 D. Krofcheck,80 P. H. Butler,81 R. Doesburg,81

H. Silverwood,81 M. Ahmad,82 I. Ahmed,82 M. I. Asghar,82 H. R. Hoorani,82 W.A. Khan,82 T. Khurshid,82 S. Qazi,82

M. Cwiok,83 W. Dominik,83 K. Doroba,83 A. Kalinowski,83 M. Konecki,83 J. Krolikowski,83 T. Frueboes,84

R. Gokieli,84 M. Górski,84 M. Kazana,84 K. Nawrocki,84 K. Romanowska-Rybinska,84 M. Szleper,84 G. Wrochna,84

P. Zalewski,84 N. Almeida,85 P. Bargassa,85 A. David,85 P. Faccioli,85 P. G. Ferreira Parracho,85 M. Gallinaro,85

P. Musella,85 A. Nayak,85 J. Seixas,85 J. Varela,85 S. Afanasiev,86 I. Belotelov,86 P. Bunin,86 I. Golutvin,86

A. Kamenev,86 V. Karjavin,86 G. Kozlov,86 A. Lanev,86 P. Moisenz,86 V. Palichik,86 V. Perelygin,86 S. Shmatov,86

V. Smirnov,86 A. Volodko,86 A. Zarubin,86 V. Golovtsov,87 Y. Ivanov,87 V. Kim,87 P. Levchenko,87 V. Murzin,87

V. Oreshkin,87 I. Smirnov,87 V. Sulimov,87 L. Uvarov,87 S. Vavilov,87 A. Vorobyev,87 A. Vorobyev,87 Yu. Andreev,88

A. Dermenev,88 S. Gninenko,88 N. Golubev,88 M. Kirsanov,88 N. Krasnikov,88 V. Matveev,88 A. Pashenkov,88

A. Toropin,88 S. Troitsky,88 V. Epshteyn,89 V. Gavrilov,89 V. Kaftanov,89,a M. Kossov,89,b A. Krokhotin,89

N. Lychkovskaya,89 V. Popov,89 G. Safronov,89 S. Semenov,89 V. Stolin,89 E. Vlasov,89 A. Zhokin,89 E. Boos,90

A. Demiyanov,90 A. Ershov,90 A. Gribushin,90 O. Kodolova,90 I. Lokhtin,90 S. Obraztsov,90 S. Petrushanko,90

L. Sarycheva,90 V. Savrin,90 A. Snigirev,90 I. Vardanyan,90 V. Andreev,91 M. Azarkin,91 I. Dremin,91

M. Kirakosyan,91 A. Leonidov,91 S. V. Rusakov,91 A. Vinogradov,91 I. Azhgirey,92 S. Bitioukov,92 V. Grishin,92,b

V. Kachanov,92 D. Konstantinov,92 A. Korablev,92 V. Krychkine,92 V. Petrov,92 R. Ryutin,92 S. Slabospitsky,92

A. Sobol,92 L. Tourtchanovitch,92 S. Troshin,92 N. Tyurin,92 A. Uzunian,92 A. Volkov,92 P. Adzic,93,t M. Djordjevic,93

D. Krpic,93,t J. Milosevic,93 M. Aguilar-Benitez,94 J. Alcaraz Maestre,94 P. Arce,94 C. Battilana,94 E. Calvo,94

M. Cepeda,94 M. Cerrada,94 N. Colino,94 B. De La Cruz,94 A. Delgado Peris,94 C. Diez Pardos,94

D. Domı́nguez Vázquez,94 C. Fernandez Bedoya,94 J. P. Fernández Ramos,94 A. Ferrando,94 J. Flix,94 M. C. Fouz,94

P. Garcia-Abia,94 O. Gonzalez Lopez,94 S. Goy Lopez,94 J.M. Hernandez,94 M. I. Josa,94 G. Merino,94

J. Puerta Pelayo,94 I. Redondo,94 L. Romero,94 J. Santaolalla,94 C. Willmott,94 C. Albajar,95 G. Codispoti,95

J. F. de Trocóniz,95 J. Cuevas,96 J. Fernandez Menendez,96 S. Folgueras,96 I. Gonzalez Caballero,96

L. Lloret Iglesias,96 J.M. Vizan Garcia,96 J. A. Brochero Cifuentes,97 I. J. Cabrillo,97 A. Calderon,97

PRL 106, 212301 (2011) P HY S I CA L R EV I EW LE T T E R S
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27 MAY 2011

212301-7



M. Chamizo Llatas,97 S. H. Chuang,97 J. Duarte Campderros,97 M. Felcini,97,u M. Fernandez,97 G. Gomez,97

J. Gonzalez Sanchez,97 C. Jorda,97 P. Lobelle Pardo,97 A. Lopez Virto,97 J. Marco,97 R. Marco,97

C. Martinez Rivero,97 F. Matorras,97 F. J. Munoz Sanchez,97 J. Piedra Gomez,97,v T. Rodrigo,97

A.Y. Rodrı́guez-Marrero,97 A. Ruiz-Jimeno,97 L. Scodellaro,97 M. Sobron Sanudo,97 I. Vila,97

R. Vilar Cortabitarte,97 D. Abbaneo,98 E. Auffray,98 G. Auzinger,98 P. Baillon,98 A.H. Ball,98 D. Barney,98

A. J. Bell,98,w D. Benedetti,98 C. Bernet,98,d W. Bialas,98 P. Bloch,98 A. Bocci,98 S. Bolognesi,98 M. Bona,98

H. Breuker,98 G. Brona,98 K. Bunkowski,98 T. Camporesi,98 G. Cerminara,98 J. A. Coarasa Perez,98 B. Curé,98

D. D’Enterria,98 A. De Roeck,98 S. Di Guida,98 A. Elliott-Peisert,98 B. Frisch,98 W. Funk,98 A. Gaddi,98 S. Gennai,98

G. Georgiou,98 H. Gerwig,98 D. Gigi,98 K. Gill,98 D. Giordano,98 F. Glege,98 R. Gomez-Reino Garrido,98

M. Gouzevitch,98 P. Govoni,98 S. Gowdy,98 L. Guiducci,98 M. Hansen,98 J. Harvey,98 J. Hegeman,98 B. Hegner,98

H. F. Hoffmann,98 A. Honma,98 V. Innocente,98 P. Janot,98 K. Kaadze,98 E. Karavakis,98 P. Lecoq,98 C. Lourenço,98

T. Mäki,98 L. Malgeri,98 M. Mannelli,98 L. Masetti,98 F. Meijers,98 S. Mersi,98 E. Meschi,98 R. Moser,98

M.U. Mozer,98 M. Mulders,98 E. Nesvold,98,b M. Nguyen,98 T. Orimoto,98 L. Orsini,98 E. Perez,98 A. Petrilli,98

A. Pfeiffer,98 M. Pierini,98 M. Pimiä,98 G. Polese,98 A. Racz,98 J. Rodrigues Antunes,98 G. Rolandi,98,x

T. Rommerskirchen,98 C. Rovelli,98,y M. Rovere,98 H. Sakulin,98 C. Schäfer,98 C. Schwick,98 I. Segoni,98

A. Sharma,98 P. Siegrist,98 M. Simon,98 P. Sphicas,98,z M. Spiropulu,98,aa F. Stöckli,98 M. Stoye,98 P. Tropea,98

A. Tsirou,98 P. Vichoudis,98 M. Voutilainen,98 W.D. Zeuner,98 W. Bertl,99 K. Deiters,99 W. Erdmann,99

K. Gabathuler,99 R. Horisberger,99 Q. Ingram,99 H. C. Kaestli,99 S. König,99 D. Kotlinski,99 U. Langenegger,99

F. Meier,99 D. Renker,99 T. Rohe,99 J. Sibille,99,bb A. Starodumov,99,cc P. Bortignon,100 L. Caminada,100,dd

Z. Chen,100 S. Cittolin,100 G. Dissertori,100 M. Dittmar,100 J. Eugster,100 K. Freudenreich,100 C. Grab,100 A. Hervé,100

W. Hintz,100 P. Lecomte,100 W. Lustermann,100 C. Marchica,100,dd P. Martinez Ruiz del Arbol,100 P. Meridiani,100

P. Milenovic,100,ee F. Moortgat,100 P. Nef,100 F. Nessi-Tedaldi,100 L. Pape,100 F. Pauss,100 T. Punz,100 A. Rizzi,100

F. J. Ronga,100 M. Rossini,100 L. Sala,100 A. K. Sanchez,100 M.-C. Sawley,100 B. Stieger,100 L. Tauscher,100,a

A. Thea,100 K. Theofilatos,100 D. Treille,100 C. Urscheler,100 R. Wallny,100 M. Weber,100 L. Wehrli,100 J. Weng,100

E. Aguiló,101 C. Amsler,101 V. Chiochia,101 S. De Visscher,101 C. Favaro,101 M. Ivova Rikova,101 B. MillanMejias,101

C. Regenfus,101 P. Robmann,101 A. Schmidt,101 H. Snoek,101 Y.H. Chang,102 E. A. Chen,102 K.H. Chen,102

W. T. Chen,102 S. Dutta,102 C.M. Kuo,102 S.W. Li,102 W. Lin,102 M.H. Liu,102 Z. K. Liu,102 Y. J. Lu,102

D. Mekterovic,102 J. H. Wu,102 S. S. Yu,102 P. Bartalini,103 P. Chang,103 Y.H. Chang,103 Y.W. Chang,103 Y. Chao,103

K. F. Chen,103 W.-S. Hou,103 Y. Hsiung,103 K.Y. Kao,103 Y. J. Lei,103 R.-S. Lu,103 J. G. Shiu,103 Y.M. Tzeng,103

M. Wang,103 A. Adiguzel,104 M.N. Bakirci,104,ff S. Cerci,104,gg Z. Demir,104 C. Dozen,104 I. Dumanoglu,104

E. Eskut,104 S. Girgis,104 G. Gokbulut,104 Y. Guler,104 E. Gurpinar,104 I. Hos,104 E. E. Kangal,104 T. Karaman,104

A. Kayis Topaksu,104 A. Nart,104 G. Onengut,104 K. Ozdemir,104 S. Ozturk,104 A. Polatoz,104 K. Sogut,104,hh

D. Sunar Cerci,104,gg B. Tali,104 H. Topakli,104,ff D. Uzun,104 L. N. Vergili,104 M. Vergili,104 C. Zorbilmez,104

I. V. Akin,105 T. Aliev,105 S. Bilmis,105 M. Deniz,105 H. Gamsizkan,105 A.M. Guler,105 K. Ocalan,105 A. Ozpineci,105

M. Serin,105 R. Sever,105 U. E. Surat,105 E. Yildirim,105 M. Zeyrek,105 M. Deliomeroglu,106 D. Demir,106,ii

E. Gülmez,106 A. Halu,106 B. Isildak,106 M. Kaya,106,jj O. Kaya,106,jj S. Ozkorucuklu,106,kk N. Sonmez,106,ll

L. Levchuk,107 P. Bell,108 F. Bostock,108 J. J. Brooke,108 T. L. Cheng,108 E. Clement,108 D. Cussans,108 R. Frazier,108

J. Goldstein,108 M. Grimes,108 M. Hansen,108 D. Hartley,108 G. P. Heath,108 H. F. Heath,108 B. Huckvale,108

J. Jackson,108 L. Kreczko,108 S. Metson,108 D.M. Newbold,108,mm K. Nirunpong,108 A. Poll,108 S. Senkin,108

V. J. Smith,108 S. Ward,108 L. Basso,109,nn K.W. Bell,109 A. Belyaev,109,nn C. Brew,109 R.M. Brown,109

B. Camanzi,109 D. J. A. Cockerill,109 J. A. Coughlan,109 K. Harder,109 S. Harper,109 B.W. Kennedy,109 E. Olaiya,109

D. Petyt,109 B. C. Radburn-Smith,109 C.H. Shepherd-Themistocleous,109 I. R. Tomalin,109 W. J. Womersley,109

S. D. Worm,109 R. Bainbridge,110 G. Ball,110 J. Ballin,110 R. Beuselinck,110 O. Buchmuller,110 D. Colling,110

N. Cripps,110 M. Cutajar,110 G. Davies,110 M. Della Negra,110 J. Fulcher,110 D. Futyan,110 A. Guneratne Bryer,110

G. Hall,110 Z. Hatherell,110 J. Hays,110 G. Iles,110 G. Karapostoli,110 B. C. MacEvoy,110 A.-M. Magnan,110

J. Marrouche,110 R. Nandi,110 J. Nash,110 A. Nikitenko,110,cc A. Papageorgiou,110 M. Pesaresi,110 K. Petridis,110

M. Pioppi,110,oo D.M. Raymond,110 N. Rompotis,110 A. Rose,110 M. J. Ryan,110 C. Seez,110 P. Sharp,110

A. Sparrow,110 A. Tapper,110 M. Vazquez Acosta,110 T. Virdee,110 S. Wakefield,110 T. Whyntie,110 M. Barrett,111

M. Chadwick,111 J. E. Cole,111 P. R. Hobson,111 A. Khan,111 P. Kyberd,111 D. Leslie,111 W. Martin,111 I. D. Reid,111

L. Teodorescu,111 K. Hatakeyama,112 T. Bose,113 E. Carrera Jarrin,113 C. Fantasia,113 A. Heister,113 J. St. John,113

P. Lawson,113 D. Lazic,113 J. Rohlf,113 D. Sperka,113 L. Sulak,113 A. Avetisyan,114 S. Bhattacharya,114 J. P. Chou,114

PRL 106, 212301 (2011) P HY S I CA L R EV I EW LE T T E R S
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27 MAY 2011

212301-8



D. Cutts,114 A. Ferapontov,114 U. Heintz,114 S. Jabeen,114 G. Kukartsev,114 G. Landsberg,114 M. Narain,114

D. Nguyen,114 M. Segala,114 T. Speer,114 K. V. Tsang,114 R. Breedon,115 M. Calderon De La Barca Sanchez,115

S. Chauhan,115 M. Chertok,115 J. Conway,115 P. T. Cox,115 J. Dolen,115 R. Erbacher,115 E. Friis,115 W. Ko,115

A. Kopecky,115 R. Lander,115 H. Liu,115 S. Maruyama,115 T. Miceli,115 M. Nikolic,115 D. Pellett,115 J. Robles,115

S. Salur,115 T. Schwarz,115 M. Searle,115 J. Smith,115 M. Squires,115 M. Tripathi,115 R. Vasquez Sierra,115

C. Veelken,115 V. Andreev,116 K. Arisaka,116 D. Cline,116 R. Cousins,116 A. Deisher,116 J. Duris,116 S. Erhan,116

C. Farrell,116 J. Hauser,116 M. Ignatenko,116 C. Jarvis,116 C. Plager,116 G. Rakness,116 P. Schlein,116,a J. Tucker,116

V. Valuev,116 J. Babb,117 A. Chandra,117 R. Clare,117 J. Ellison,117 J.W. Gary,117 F. Giordano,117 G. Hanson,117

G.Y. Jeng,117 S. C. Kao,117 F. Liu,117 H. Liu,117 O. R. Long,117 A. Luthra,117 H. Nguyen,117 B. C. Shen,117,a

R. Stringer,117 J. Sturdy,117 S. Sumowidagdo,117 R. Wilken,117 S. Wimpenny,117 W. Andrews,118 J. G. Branson,118

G. B. Cerati,118 E. Dusinberre,118 D. Evans,118 F. Golf,118 A. Holzner,118 R. Kelley,118 M. Lebourgeois,118 J. Letts,118

B. Mangano,118 S. Padhi,118 C. Palmer,118 G. Petrucciani,118 H. Pi,118 M. Pieri,118 R. Ranieri,118 M. Sani,118

V. Sharma,118,b S. Simon,118 Y. Tu,118 A. Vartak,118 S. Wasserbaech,118,pp F. Würthwein,118 A. Yagil,118 D. Barge,119

R. Bellan,119 C. Campagnari,119 M. D’Alfonso,119 T. Danielson,119 K. Flowers,119 P. Geffert,119 J. Incandela,119

C. Justus,119 P. Kalavase,119 S. A. Koay,119 D. Kovalskyi,119 V. Krutelyov,119 S. Lowette,119 N. Mccoll,119

V. Pavlunin,119 F. Rebassoo,119 J. Ribnik,119 J. Richman,119 R. Rossin,119 D. Stuart,119 W. To,119 J. R. Vlimant,119

A. Apresyan,120 A. Bornheim,120 J. Bunn,120 Y. Chen,120 M. Gataullin,120 Y. Ma,120 A. Mott,120 H. B. Newman,120

C. Rogan,120 V. Timciuc,120 P. Traczyk,120 J. Veverka,120 R. Wilkinson,120 Y. Yang,120 R.Y. Zhu,120 B. Akgun,121

R. Carroll,121 T. Ferguson,121 Y. Iiyama,121 D.W. Jang,121 S. Y. Jun,121 Y. F. Liu,121 M. Paulini,121 J. Russ,121

H. Vogel,121 I. Vorobiev,121 J. P. Cumalat,122 M. E. Dinardo,122 B. R. Drell,122 C. J. Edelmaier,122 W. T. Ford,122

A. Gaz,122 B. Heyburn,122 E. Luiggi Lopez,122 U. Nauenberg,122 J. G. Smith,122 K. Stenson,122 K.A. Ulmer,122

S. R. Wagner,122 S. L. Zang,122 L. Agostino,123 J. Alexander,123 D. Cassel,123 A. Chatterjee,123 S. Das,123

N. Eggert,123 L. K. Gibbons,123 B. Heltsley,123 W. Hopkins,123 A. Khukhunaishvili,123 B. Kreis,123

G. Nicolas Kaufman,123 J. R. Patterson,123 D. Puigh,123 A. Ryd,123 X. Shi,123 W. Sun,123 W.D. Teo,123 J. Thom,123

J. Thompson,123 J. Vaughan,123 Y. Weng,123 L. Winstrom,123 P. Wittich,123 A. Biselli,124 G. Cirino,124 D. Winn,124

S. Abdullin,125 M. Albrow,125 J. Anderson,125 G. Apollinari,125 M. Atac,125 J. A. Bakken,125 S. Banerjee,125

L. A. T. Bauerdick,125 A. Beretvas,125 J. Berryhill,125 P. C. Bhat,125 I. Bloch,125 F. Borcherding,125 K. Burkett,125

J. N. Butler,125 V. Chetluru,125 H.W.K. Cheung,125 F. Chlebana,125 S. Cihangir,125 W. Cooper,125 D. P. Eartly,125

V.D. Elvira,125 S. Esen,125 I. Fisk,125 J. Freeman,125 Y. Gao,125 E. Gottschalk,125 D. Green,125 K. Gunthoti,125

O. Gutsche,125 J. Hanlon,125 R.M. Harris,125 J. Hirschauer,125 B. Hooberman,125 H. Jensen,125 M. Johnson,125

U. Joshi,125 R. Khatiwada,125 B. Klima,125 K. Kousouris,125 S. Kunori,125 S. Kwan,125 C. Leonidopoulos,125

P. Limon,125 D. Lincoln,125 R. Lipton,125 J. Lykken,125 K. Maeshima,125 J.M. Marraffino,125 D. Mason,125

P. McBride,125 T. Miao,125 K. Mishra,125 S. Mrenna,125 Y. Musienko,125,qq C. Newman-Holmes,125 V. O’Dell,125

R. Pordes,125 O. Prokofyev,125 N. Saoulidou,125 E. Sexton-Kennedy,125 S. Sharma,125 W. J. Spalding,125

L. Spiegel,125 P. Tan,125 L. Taylor,125 S. Tkaczyk,125 L. Uplegger,125 E.W. Vaandering,125 R. Vidal,125

J. Whitmore,125 W. Wu,125 F. Yang,125 F. Yumiceva,125 J. C. Yun,125 D. Acosta,126 P. Avery,126 D. Bourilkov,126

M. Chen,126 G. P. Di Giovanni,126 D. Dobur,126 A. Drozdetskiy,126 R. D. Field,126 M. Fisher,126 Y. Fu,126

I. K. Furic,126 J. Gartner,126 S. Goldberg,126 B. Kim,126 J. Konigsberg,126 A. Korytov,126 A. Kropivnitskaya,126

T. Kypreos,126 K. Matchev,126 G. Mitselmakher,126 L. Muniz,126 Y. Pakhotin,126 C. Prescott,126 R. Remington,126

M. Schmitt,126 B. Scurlock,126 P. Sellers,126 N. Skhirtladze,126 D. Wang,126 J. Yelton,126 M. Zakaria,126 C. Ceron,127

V. Gaultney,127 L. Kramer,127 L.M. Lebolo,127 S. Linn,127 P. Markowitz,127 G. Martinez,127 J. L. Rodriguez,127

T. Adams,128 A. Askew,128 D. Bandurin,128 J. Bochenek,128 J. Chen,128 B. Diamond,128 S. V. Gleyzer,128 J. Haas,128

V. Hagopian,128 M. Jenkins,128 K. F. Johnson,128 H. Prosper,128 L. Quertenmont,128 S. Sekmen,128

V. Veeraraghavan,128 M.M. Baarmand,129 B. Dorney,129 S. Guragain,129 M. Hohlmann,129 H. Kalakhety,129

R. Ralich,129 I. Vodopiyanov,129 M.R. Adams,130 I.M. Anghel,130 L. Apanasevich,130 Y. Bai,130 V. E. Bazterra,130

R. R. Betts,130 J. Callner,130 R. Cavanaugh,130 C. Dragoiu,130 L. Gauthier,130 C. E. Gerber,130 D. J. Hofman,130

S. Khalatyan,130 G. J. Kunde,130,rr F. Lacroix,130 M. Malek,130 C. O’Brien,130 C. Silvestre,130 A. Smoron,130

D. Strom,130 N. Varelas,130 U. Akgun,131 E. A. Albayrak,131 B. Bilki,131 W. Clarida,131 F. Duru,131 C. K. Lae,131

E. McCliment,131 J.-P. Merlo,131 H. Mermerkaya,131 A. Mestvirishvili,131 A. Moeller,131 J. Nachtman,131

C. R. Newsom,131 E. Norbeck,131 J. Olson,131 Y. Onel,131 F. Ozok,131 S. Sen,131 J. Wetzel,131 T. Yetkin,131 K. Yi,131

B. A. Barnett,132 B. Blumenfeld,132 A. Bonato,132 C. Eskew,132 D. Fehling,132 G. Giurgiu,132 A. V. Gritsan,132

PRL 106, 212301 (2011) P HY S I CA L R EV I EW LE T T E R S
week ending
27 MAY 2011

212301-9



G. Hu,132 P. Maksimovic,132 S. Rappoccio,132 M. Swartz,132 N.V. Tran,132 A. Whitbeck,132 P. Baringer,133

A. Bean,133 G. Benelli,133 O. Grachov,133 M. Murray,133 D. Noonan,133 S. Sanders,133 J. S. Wood,133 V. Zhukova,133

A. F. Barfuss,134 T. Bolton,134 I. Chakaberia,134 A. Ivanov,134 M. Makouski,134 Y. Maravin,134 S. Shrestha,134

I. Svintradze,134 Z. Wan,134 J. Gronberg,135 D. Lange,135 D. Wright,135 A. Baden,136 M. Boutemeur,136 S. C. Eno,136

D. Ferencek,136 J. A. Gomez,136 N. J. Hadley,136 R. G. Kellogg,136 M. Kirn,136 Y. Lu,136 A. C. Mignerey,136

K. Rossato,136 P. Rumerio,136 F. Santanastasio,136 A. Skuja,136 J. Temple,136 M.B. Tonjes,136 S. C. Tonwar,136

E. Twedt,136 B. Alver,137 G. Bauer,137 J. Bendavid,137 W. Busza,137 E. Butz,137 I. A. Cali,137 M. Chan,137 V. Dutta,137

P. Everaerts,137 G. Gomez Ceballos,137 M. Goncharov,137 K.A. Hahn,137 P. Harris,137 Y. Kim,137 M. Klute,137

Y.-J. Lee,137 W. Li,137 C. Loizides,137 P. D. Luckey,137 T. Ma,137 S. Nahn,137 C. Paus,137 D. Ralph,137 C. Roland,137

G. Roland,137 M. Rudolph,137 G. S. F. Stephans,137 K. Sumorok,137 K. Sung,137 E. A. Wenger,137 S. Xie,137

M. Yang,137 Y. Yilmaz,137 A. S. Yoon,137 M. Zanetti,137 P. Cole,138 S. I. Cooper,138 P. Cushman,138 B. Dahmes,138

A. De Benedetti,138 P. R. Dudero,138 G. Franzoni,138 J. Haupt,138 K. Klapoetke,138 Y. Kubota,138 J. Mans,138

V. Rekovic,138 R. Rusack,138 M. Sasseville,138 A. Singovsky,138 L.M. Cremaldi,139 R. Godang,139 R. Kroeger,139

L. Perera,139 R. Rahmat,139 D.A. Sanders,139 D. Summers,139 K. Bloom,140 S. Bose,140 J. Butt,140 D. R. Claes,140

A. Dominguez,140 M. Eads,140 J. Keller,140 T. Kelly,140 I. Kravchenko,140 J. Lazo-Flores,140 H. Malbouisson,140

S. Malik,140 G. R. Snow,140 U. Baur,141 A. Godshalk,141 I. Iashvili,141 S. Jain,141 A. Kharchilava,141 A. Kumar,141

S. P. Shipkowski,141 K. Smith,141 G. Alverson,142 E. Barberis,142 D. Baumgartel,142 O. Boeriu,142 M. Chasco,142

S. Reucroft,142 J. Swain,142 D. Wood,142 J. Zhang,142 A. Anastassov,143 A. Kubik,143 N. Odell,143

R.A. Ofierzynski,143 B. Pollack,143 A. Pozdnyakov,143 M. Schmitt,143 S. Stoynev,143 M. Velasco,143 S. Won,143

L. Antonelli,144 D. Berry,144 M. Hildreth,144 C. Jessop,144 D. J. Karmgard,144 J. Kolb,144 T. Kolberg,144 K. Lannon,144

W. Luo,144 S. Lynch,144 N. Marinelli,144 D.M. Morse,144 T. Pearson,144 R. Ruchti,144 J. Slaunwhite,144 N. Valls,144

M. Wayne,144 J. Ziegler,144 B. Bylsma,145 L. S. Durkin,145 J. Gu,145 C. Hill,145 P. Killewald,145 K. Kotov,145

M. Rodenburg,145 G. Williams,145 N. Adam,146 E. Berry,146 P. Elmer,146 D. Gerbaudo,146 V. Halyo,146 P. Hebda,146

A. Hunt,146 J. Jones,146 E. Laird,146 D. Lopes Pegna,146 D. Marlow,146 T. Medvedeva,146 M. Mooney,146 J. Olsen,146

P. Piroué,146 X. Quan,146 H. Saka,146 D. Stickland,146 C. Tully,146 J. S. Werner,146 A. Zuranski,146 J. G. Acosta,147

X. T. Huang,147 A. Lopez,147 H. Mendez,147 S. Oliveros,147 J. E. Ramirez Vargas,147 A. Zatserklyaniy,147

E. Alagoz,148 V. E. Barnes,148 G. Bolla,148 L. Borrello,148 D. Bortoletto,148 A. Everett,148 A. F. Garfinkel,148

L. Gutay,148 Z. Hu,148 M. Jones,148 O. Koybasi,148 M. Kress,148 A. T. Laasanen,148 N. Leonardo,148 C. Liu,148

V. Maroussov,148 P. Merkel,148 D.H. Miller,148 N. Neumeister,148 I. Shipsey,148 D. Silvers,148 A. Svyatkovskiy,148

H.D. Yoo,148 J. Zablocki,148 Y. Zheng,148 P. Jindal,149 N. Parashar,149 C. Boulahouache,150 V. Cuplov,150

K.M. Ecklund,150 F. J.M. Geurts,150 B. P. Padley,150 R. Redjimi,150 J. Roberts,150 J. Zabel,150 B. Betchart,151

A. Bodek,151 Y. S. Chung,151 R. Covarelli,151 P. de Barbaro,151 R. Demina,151 Y. Eshaq,151 H. Flacher,151

A. Garcia-Bellido,151 P. Goldenzweig,151 Y. Gotra,151 J. Han,151 A. Harel,151 D. C. Miner,151 D. Orbaker,151

G. Petrillo,151 D. Vishnevskiy,151 M. Zielinski,151 A. Bhatti,152 R. Ciesielski,152 L. Demortier,152 K. Goulianos,152

G. Lungu,152 C. Mesropian,152 M. Yan,152 O. Atramentov,153 A. Barker,153 D. Duggan,153 Y. Gershtein,153

R. Gray,153 E. Halkiadakis,153 D. Hidas,153 D. Hits,153 A. Lath,153 S. Panwalkar,153 R. Patel,153 A. Richards,153

K. Rose,153 S. Schnetzer,153 S. Somalwar,153 R. Stone,153 S. Thomas,153 G. Cerizza,154 M. Hollingsworth,154

S. Spanier,154 Z. C. Yang,154 A. York,154 J. Asaadi,155 R. Eusebi,155 J. Gilmore,155 A. Gurrola,155 T. Kamon,155

V. Khotilovich,155 R. Montalvo,155 C. N. Nguyen,155 I. Osipenkov,155 J. Pivarski,155 A. Safonov,155 S. Sengupta,155

A. Tatarinov,155 D. Toback,155 M. Weinberger,155 N. Akchurin,156 J. Damgov,156 C. Jeong,156 K. Kovitanggoon,156

S.W. Lee,156 Y. Roh,156 A. Sill,156 I. Volobouev,156 R. Wigmans,156 E. Yazgan,156 E. Appelt,157 E. Brownson,157

D. Engh,157 C. Florez,157 W. Gabella,157 M. Issah,157 W. Johns,157 P. Kurt,157 C. Maguire,157 A. Melo,157

P. Sheldon,157 S. Tuo,157 J. Velkovska,157 M.W. Arenton,158 M. Balazs,158 S. Boutle,158 M. Buehler,158 S. Conetti,158

B. Cox,158 B. Francis,158 R. Hirosky,158 A. Ledovskoy,158 C. Lin,158 C. Neu,158 R. Yohay,158 S. Gollapinni,159

R. Harr,159 P. E. Karchin,159 P. Lamichhane,159 M. Mattson,159 C. Milstène,159 A. Sakharov,159 M. Anderson,160

M. Bachtis,160 J. N. Bellinger,160 D. Carlsmith,160 S. Dasu,160 J. Efron,160 K. Flood,160 L. Gray,160 K. S. Grogg,160

M. Grothe,160 R. Hall-Wilton,160,b M. Herndon,160 P. Klabbers,160 J. Klukas,160 A. Lanaro,160 C. Lazaridis,160

J. Leonard,160 R. Loveless,160 A. Mohapatra,160 D. Reeder,160 I. Ross,160 A. Savin,160 W.H. Smith,160

J. Swanson,160 and M. Weinberg160

(CMS Collaboration)

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1Yerevan Physics Institute, Yerevan, Armenia
2Institut für Hochenergiephysik der OeAW, Wien, Austria

3National Centre for Particle and High Energy Physics, Minsk, Belarus
4Universiteit Antwerpen, Antwerpen, Belgium
5Vrije Universiteit Brussel, Brussel, Belgium

6Université Libre de Bruxelles, Bruxelles, Belgium
7Ghent University, Ghent, Belgium

8Université Catholique de Louvain, Louvain-la-Neuve, Belgium
9Université de Mons, Mons, Belgium

10Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil
11Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil

12Instituto de Fisica Teorica, Universidade Estadual Paulista, Sao Paulo, Brazil
13Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria

14University of Sofia, Sofia, Bulgaria
15Institute of High Energy Physics, Beijing, China

16State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China
17Universidad de Los Andes, Bogota, Colombia
18Technical University of Split, Split, Croatia

19University of Split, Split, Croatia
20Institute Rudjer Boskovic, Zagreb, Croatia

21University of Cyprus, Nicosia, Cyprus
22Charles University, Prague, Czech Republic

23Academy of Scientific Research and Technology of the Arab Republic of Egypt,
Egyptian Network of High Energy Physics, Cairo, Egypt

24National Institute of Chemical Physics and Biophysics, Tallinn, Estonia
25Department of Physics, University of Helsinki, Helsinki, Finland

26Helsinki Institute of Physics, Helsinki, Finland
27Lappeenranta University of Technology, Lappeenranta, Finland

28Laboratoire d’Annecy-le-Vieux de Physique des Particules, IN2P3-CNRS, Annecy-le-Vieux, France
29DSM/IRFU, CEA/Saclay, Gif-sur-Yvette, France

30Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France
31Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Université de Haute Alsace Mulhouse,

CNRS/IN2P3, Strasbourg, France
32Centre de Calcul de l’Institut National de Physique Nucleaire et de Physique des Particules (IN2P3), Villeurbanne, France

33Université de Lyon, Université Claude Bernard Lyon 1, CNRS-IN2P3, Institut de Physique Nucléaire de Lyon, Villeurbanne, France
34E. Andronikashvili Institute of Physics, Academy of Science, Tbilisi, Georgia

35Institute of High Energy Physics and Informatization, Tbilisi State University, Tbilisi, Georgia
36RWTH Aachen University, I. Physikalisches Institut, Aachen, Germany

37RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany
38RWTH Aachen University, III. Physikalisches Institut B, Aachen, Germany

39Deutsches Elektronen-Synchrotron, Hamburg, Germany
40University of Hamburg, Hamburg, Germany

41Institut für Experimentelle Kernphysik, Karlsruhe, Germany
42Institute of Nuclear Physics ‘‘Demokritos,’’ Aghia Paraskevi, Greece

43University of Athens, Athens, Greece
44University of Ioánnina, Ioánnina, Greece

45KFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary
46Institute of Nuclear Research ATOMKI, Debrecen, Hungary

47University of Debrecen, Debrecen, Hungary
48Panjab University, Chandigarh, India

49University of Delhi, Delhi, India
50Bhabha Atomic Research Centre, Mumbai, India

51Tata Institute of Fundamental Research—EHEP, Mumbai, India
52Tata Institute of Fundamental Research—HECR, Mumbai, India

53Institute for Research and Fundamental Sciences (IPM), Tehran, Iran
54INFN Sezione di Bari, Università di Bari, Politecnico di Bari, Bari, Italy

54aINFN Sezione di Bari, Bari, Italy
54bUniversità di Bari, Bari Italy
54cPolitecnico di Bari, Bari, Italy

55INFN Sezione di Bologna, Università di Bologna, Bologna, Italy
55aINFN Sezione di Bologna, Bologna, Italy

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55bUniversità di Bologna, Bologna, Italy
56INFN Sezione di Catania, Università di Catania, Catania, Italy

56aINFN Sezione di Catania, Catania, Italy
56bUniversità di Catania, Catania, Italy

57INFN Sezione di Firenze, Università di Firenze, Firenze, Italy
57aINFN Sezione di Firenze, Firenze, Italy
57bUniversità di Firenze, Firenze, Italy

58INFN Laboratori Nazionali di Frascati, Frascati, Italy
59INFN Sezione di Genova, Genova, Italy

60INFN Sezione di Milano-Biccoca, Università di Milano-Bicocca, Milano, Italy
60aINFN Sezione di Milano-Biccoca, Milano, Italy
60bUniversità di Milano-Bicocca, Milano, Italy

61INFN Sezione di Napoli, Università di Napoli ‘‘Federico II,’’ Napoli, Italy
61aINFN Sezione di Napoli, Napoli, Italy

61bUniversità di Napoli ‘‘Federico II,’’ Napoli, Italy
62INFN Sezione di Padova, Università di Padova, Università di Trento (Trento), Padova, Italy

62aINFN Sezione di Padova, Padova, Italy
62bUniversità di Padova, Padova, Italy

62cUniversità di Trento (Trento), Padova, Italy
63INFN Sezione di Pavia, Università di Pavia, Pavia, Italy

63aINFN Sezione di Pavia, Pavia, Italy
63bUniversità di Pavia, Pavia, Italy

64INFN Sezione di Perugia, Università di Perugia, Perugia, Italy
64aINFN Sezione di Perugia, Perugia, Italy
64bUniversità di Perugia, Perugia, Italy

65INFN Sezione di Pisa, Università di Pisa, Scuola Normale Superiore di Pisa, Pisa, Italy
65aINFN Sezione di Pisa, Pisa, Italy
65bUniversità di Pisa, Pisa, Italy

65cScuola Normale Superiore di Pisa, Pisa, Italy
66INFN Sezione di Roma, Università di Roma ‘‘La Sapienza,’’ Roma, Italy

66aINFN Sezione di Roma, Roma, Italy
66bUniversità di Roma ‘‘La Sapienza,’’ Roma, Italy

67INFN Sezione di Torino, Università di Torino, Università del Piemonte Orientale (Novara), Torino, Italy
67aINFN Sezione di Torino, Torino, Italy
67bUniversità di Torino, Torino, Italy

67cUniversità del Piemonte Orientale (Novara), Torino, Italy
68INFN Sezione di Trieste, Università di Trieste, Trieste, Italy

68aINFN Sezione di Trieste, Trieste, Italy
68bUniversità di Trieste, Trieste, Italy

69Kangwon National University, Chunchon, Korea
70Kyungpook National University, Daegu, Korea

71Chonnam National University, Institute for Universe and Elementary Particles, Kwangju, Korea
72Korea University, Seoul, Korea

73University of Seoul, Seoul, Korea
74Sungkyunkwan University, Suwon, Korea

75Vilnius University, Vilnius, Lithuania
76Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico

77Universidad Iberoamericana, Mexico City, Mexico
78Benemerita Universidad Autonoma de Puebla, Puebla, Mexico

79Universidad Autónoma de San Luis Potosı́, San Luis Potosı́, Mexico
80University of Auckland, Auckland, New Zealand

81University of Canterbury, Christchurch, New Zealand
82National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan

83Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
84Soltan Institute for Nuclear Studies, Warsaw, Poland

85Laboratório de Instrumentação e Fı́sica Experimental de Partı́culas, Lisboa, Portugal
86Joint Institute for Nuclear Research, Dubna, Russia

87Petersburg Nuclear Physics Institute, Gatchina (St Petersburg), Russia
88Institute for Nuclear Research, Moscow, Russia

89Institute for Theoretical and Experimental Physics, Moscow, Russia
90Moscow State University, Moscow, Russia

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91P.N. Lebedev Physical Institute, Moscow, Russia
92State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, Russia

93University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia
94Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain

95Universidad Autónoma de Madrid, Madrid, Spain
96Universidad de Oviedo, Oviedo, Spain

97Instituto de Fı́sica de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain
98CERN, European Organization for Nuclear Research, Geneva, Switzerland

99Paul Scherrer Institut, Villigen, Switzerland
100Institute for Particle Physics, ETH Zurich, Zurich, Switzerland

101Universität Zürich, Zurich, Switzerland
102National Central University, Chung-Li, Taiwan

103National Taiwan University (NTU), Taipei, Taiwan
104Cukurova University, Adana, Turkey

105Middle East Technical University, Physics Department, Ankara, Turkey
106Bogazici University, Istanbul, Turkey

107National Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, Ukraine
108University of Bristol, Bristol, United Kingdom

109Rutherford Appleton Laboratory, Didcot, United Kingdom
110Imperial College, London, United Kingdom

111Brunel University, Uxbridge, United Kingdom
112Baylor University, Waco, USA
113Boston University, Boston, USA

114Brown University, Providence, USA
115University of California, Davis, Davis, USA

116University of California, Los Angeles, Los Angeles, USA
117University of California, Riverside, Riverside, USA
118University of California, San Diego, La Jolla, USA

119University of California, Santa Barbara, Santa Barbara, USA
120California Institute of Technology, Pasadena, USA

121Carnegie Mellon University, Pittsburgh, USA
122University of Colorado at Boulder, Boulder, USA

123Cornell University, Ithaca, USA
124Fairfield University, Fairfield, USA

125Fermi National Accelerator Laboratory, Batavia, USA
126University of Florida, Gainesville, USA

127Florida International University, Miami, USA
128Florida State University, Tallahassee, USA

129Florida Institute of Technology, Melbourne, USA
130University of Illinois at Chicago (UIC), Chicago, USA

131The University of Iowa, Iowa City, USA
132Johns Hopkins University, Baltimore, USA
133The University of Kansas, Lawrence, USA
134Kansas State University, Manhattan, USA

135Lawrence Livermore National Laboratory, Livermore, USA
136University of Maryland, College Park, USA

137Massachusetts Institute of Technology, Cambridge, USA
138University of Minnesota, Minneapolis, USA
139University of Mississippi, University, USA

140University of Nebraska-Lincoln, Lincoln, USA
141State University of New York at Buffalo, Buffalo, USA

142Northeastern University, Boston, USA
143Northwestern University, Evanston, USA

144University of Notre Dame, Notre Dame, USA
145The Ohio State University, Columbus, USA

146Princeton University, Princeton, USA
147University of Puerto Rico, Mayaguez, USA
148Purdue University, West Lafayette, USA

149Purdue University Calumet, Hammond, USA
150Rice University, Houston, USA

151University of Rochester, Rochester, USA

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152The Rockefeller University, New York, USA
153Rutgers, the State University of New Jersey, Piscataway, USA

154University of Tennessee, Knoxville, USA
155Texas A&M University, College Station, USA

156Texas Tech University, Lubbock, USA
157Vanderbilt University, Nashville, USA

158University of Virginia, Charlottesville, USA
159Wayne State University, Detroit, USA

160University of Wisconsin, Madison, USA

aDeceased.
bAlso at CERN, European Organization for Nuclear Research, Geneva, Switzerland.
cAlso at Universidade Federal do ABC, Santo Andre, Brazil.
dAlso at Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France.
eAlso at Suez Canal University, Suez, Egypt.
fAlso at British University, Cairo, Egypt.
gAlso at Soltan Institute for Nuclear Studies, Warsaw, Poland.
hAlso at Massachusetts Institute of Technology, Cambridge, USA.
iAlso at Université de Haute-Alsace, Mulhouse, France.
jAlso at Brandenburg University of Technology, Cottbus, Germany.
kAlso at Moscow State University, Moscow, Russia.
lAlso at Institute of Nuclear Research ATOMKI, Debrecen, Hungary.

mAlso at Eötvös Loránd University, Budapest, Hungary.
nAlso at Tata Institute of Fundamental Research - HECR, Mumbai, India.
oAlso at University of Visva-Bharati, Santiniketan, India.
pAlso at Facoltà Ingegneria Università di Roma ‘‘La Sapienza,’’ Roma, Italy.
qAlso at Università della Basilicata, Potenza, Italy.
rAlso at Laboratori Nazionali di Legnaro dell’INFN, Legnaro, Italy.
sAlso at Università degli studi di Siena, Siena, Italy.
tAlso at Faculty of Physics of University of Belgrade, Belgrade, Serbia.
uAlso at University of California, Los Angeles, Los Angeles, USA.
vAlso at University of Florida, Gainesville, USA.
wAlso at Université de Genève, Geneva, Switzerland.
xAlso at Scuola Normale e Sezione dell’ INFN, Pisa, Italy.
yAlso at INFN Sezione di Roma, Università di Roma ‘‘La Sapienza,’’ Roma, Italy.
zAlso at University of Athens, Athens, Greece.
aaAlso at California Institute of Technology, Pasadena, USA.
bbAlso at The University of Kansas, Lawrence, USA.
ccAlso at Institute for Theoretical and Experimental Physics, Moscow, Russia.
ddAlso at Paul Scherrer Institut, Villigen, Switzerland.
eeAlso at University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia.
ffAlso at Gaziosmanpasa University, Tokat, Turkey.
ggAlso at Adiyaman University, Adiyaman, Turkey.
hhAlso at Mersin University, Mersin, Turkey.
iiAlso at Izmir Institute of Technology, Izmir, Turkey.
jjAlso at Kafkas University, Kars, Turkey.
kkAlso at Suleyman Demirel University, Isparta, Turkey.
llAlso at Ege University, Izmir, Turkey.

mmAlso at Rutherford Appleton Laboratory, Didcot, United Kingdom.
nnAlso at School of Physics and Astronomy, University of Southampton, Southampton, United Kingdom.
ooAlso at INFN Sezione di Perugia, Università di Perugia, Perugia, Italy.
ppAlso at Utah Valley University, Orem, USA.
qqAlso at Institute for Nuclear Research, Moscow, Russia.
rrAlso at Los Alamos National Laboratory, Los Alamos, USA.

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