Measurement of CP asymmetries in two-body B (s)0 -meson decays to charged pions and kaons

Abstract

CP asymmetries have been measured recently by the LHCb collaboration in three-body B+ decays to final states involving charged pions and kaons. Large asymmetries with opposite signs at a level of about 60% have been observed in B± → π ±(or K±)π +π − and B± → π ±K+K− for restricted regions in the Dalitz plots involving π +π − and K+K− with low invariant mass. U-spin is shown to predict corresponding ∆S = 0 and ∆S = 1 asymmetries with opposite signs and inversely proportional to their branching ratios, in analogy with a successful relation predicted thirteen years ago between asymmetries in Bs → K−π + and B0 → K+π −. We compare these predictions with the measured integrated asymmetries. Effects of specific resonant or non-resonant partial waves on enhanced asymmetries for low-pair-mass regions of the Dalitz plot are studied in B± → π ±π +π −. The closure of low-mass π +π − and K+K− channels involving only ππ ↔ KK¯ rescattering may explain by CPT approximately equal magnitudes and opposite signs measured in B± → π ±π +π − and B± → π ±K+K−.