Search for new physics in $B \to K ππγ$ with Belle II data

Abstract

The measurement of the time-dependent CP-asymmetry of $B^0 \to K_S^0 π^+ π^- γ$ decays is sensitive to contributions from physics beyond the Standard Model. To translate this measurement into a constraint on new physics, it is necessary to distinguish between decay modes that contribute to the final state via a kaonic resonance that is a CP eigenstate, and those that proceed through non-CP eigenstates. This requires an amplitude analysis of the $B \to K_{res} γ\to K π^+ π^- γ$ decay, that is discussed in this article.