Improved K e3 radiative corrections sharpen the K μ2–K l3 discrepancy

Abstract

Abstract The measurements of V us in leptonic (K μ2) and semileptonic (K l3) kaon decays exhibit a 3σ disagreement, which could originate either from physics beyond the Standard Model or some large unidentified Standard Model systematic effects. Clarifying this issue requires a careful examination of all existing Standard Model inputs. Making use of a newly-proposed computational framework and the most recent lattice QCD results, we perform a comprehensive re-analysis of the electroweak radiative corrections to the K e3 decay rates that achieves an unprecedented level of precision of 10 −4, which improves the current best results by almost an order of magnitude. No large systematic effects are found, which suggests that the electroweak radiative corrections should be removed from the “list of culprits” responsible for the K μ2–K l3 discrepancy.

Keywords

• Kaon Physics
• Lattice QCD
• Precision QED