2007/05/31 by Federico Mescia, Christopher Smith · 2 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.1103/physrevd.76.034017
published as Phys.Rev.D76:034017,2007 · 16 pages, 1 figure. Numerical analysis updated to include the recent Kl3 data. To appear in Phys. Rev. D
arxiv created 2007/08/28 · openalex publication_date 2007/08/28 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The estimation of rare K decay matrix elements from K_\ensuremathℓ3 experimental data is extended beyond LO in chiral perturbation theory. Isospin-breaking effects at next-to-leading order (and partially next-to-next-to-leading order) in the chiral perturbation theory expansion, as well as QED radiative corrections, are now accounted for. The analysis relies mainly on the cleanness of two specific ratios of form factors, for which the theoretical control is excellent. As a result, the uncertainties on the K+\ensuremath→\ensuremathπ+\ensuremathν\ensuremathν and KL\ensuremath→\ensuremathπ0\ensuremathν\ensuremathν matrix elements are reduced by a factor of about 7 and 4, respectively, and similarly for the direct CP-violating contributions to KL\ensuremath→\ensuremathπ0e+e^\ensuremath- and KL\ensuremath→\ensuremathπ0\ensuremathμ+\ensuremathμ^\ensuremath-. They could be reduced even further with better experimental data for the K_\ensuremathℓ3 slopes and the K_\ensuremathℓ3+ branching ratios. As a result, the nonparametric errors for B(K\ensuremath→\ensuremathπ\ensuremathν\ensuremathν) and for the direct CP-violating contributions to B(KL\ensuremath→\ensuremathπ0\ensuremathℓ+\ensuremathℓ^\ensuremath-) are now completely dominated by those on the short-distance physics.