KL to pi0 e+ e- and KL to pi0 mu+ mu- : A binary star on the stage of flavor physics

Abstract

A systematic analysis of New Physics impacts on the rare decays KL to pi0 l+ l- is performed. Thanks to their different sensitivities to flavor-changing local effective interactions, these two modes could provide valuable information on the nature of the possible New Physics at play. In particular, a combined measurement of both modes could disentangle scalar/pseudoscalar from vector or axial-vector contributions. For the latter, model-independent bounds are derived. Finally, the KL to pi0 mu+ mu- forward-backward CP-asymmetry is considered, and shown to give interesting complementary information.

Comments: 20 pages, 5 figures. Comments and references added, minor numerical changes, conclusion unchanged, to appear in JHEP