Scalar scenarios contributing to [Formula Presented] with enhanced Yukawa couplings

In this work we address contributions from scalars to (Formula presented) In order to explain the recently measured deviation by the BNL experiment on (Formula presented) it is necessary that these scalars are either light or couple strongly with muons. Here we explore this last possibility. We show that a scalar with mass of the order of (Formula presented) provides significant contribution to (Formula presented) if the Yukawa coupling is about (Formula presented) We suggest scenarios where this comes about naturally. © 2001 The American Physical Society.