Amplitude Analysis of the Decay B 0 → KS0 π+π- and First Observation of the CP Asymmetry in B 0 →k∗ (892)-π+

Abstract

The time-integrated untagged Dalitz plot of the three-body hadronic charmless decay ¯ B 0 → K 0 S π + π − is studied using a p p collision data sample recorded with the LHCb detector, corresponding to an integrated luminosity of 3.0 fb − 1 . The decay amplitude is described with an isobar model. Relative contributions of the isobar amplitudes to the ¯ B 0 → K 0 S π + π − decay branching fraction and C P asymmetries of the flavor-specific amplitudes are measured. The C P asymmetry between the conjugate ¯ B 0 → K ∗ ( 892 ) − π + and B 0 → K ∗ ( 892 ) + π − decay rates is determined to be − 0.308 ± 0.062.