Soft-photon corrections in multi-body meson decays

TL;DR

This paper derives universal soft-photon correction factors for multi-body meson decays, accounting for virtual and real emissions, with implications for Dalitz plot analyses in K decays.

Contribution

It provides analytic formulas for O(alpha) corrections applicable to various meson decay modes with soft-photon energy cuts, including all-order resummations.

Findings

Universal correction factors derived for B, D, K meson decays.

Application to Dalitz plot distortions in K -> 3 pi decays.

Discussion of resummation techniques for different velocity regimes.

Abstract

The effects due to soft-photon emission (and the related virtual corrections) in multi-body decays of B, D, and K mesons are analysed. We present analytic expressions for the universal O(alpha) correction factors which can be applied to all multi-body decay modes where a tight soft-photon energy cut in the decaying-particle rest-frame is applied. All-order resummations valid in the limit of small and large velocities of the final-state particles are also discussed. The phenomenological implications of these correction factors in the distortion of Dalitz-plot distributions of K -> 3 pi decays are briefly analysed.