Radiative modes $K^{+}\to {\pi }^{+}{\gamma }^{\ast }{\gamma }^{(\ast )}$ and the $K^{+}\to {\pi }^{+}4e$ decay

Abstract

We discuss radiative transitions of a charged kaon to a pion and two photons. In particular, we have a closer look at radiative corrections for the $K^{+}\to {\pi }^{+}{\ell }^{+}{\ell }^{-}$ decays and present the branching ratio of the $K^{+}\to {\pi }^{+}{e}^{+}{e}^{-}{e}^{+}{e}^{-}$ process calculated for the first time at leading order in the Standard Model.

Comments: 5 pages, 3 figures, 1 table; contribution to the proceedings of International Conference on Kaon Physics 2022 (KAON2022)