Measurement of the Ratio BR(B- --> D*0 K-)/BR(B- --> D*0 pi-) and the CP-asymmetry of B- --> D*0(CP+) K- decays with the BABAR detector

TL;DR

This paper measures the ratios of specific B- meson decay rates involving D*0 and kaons or pions, and investigates CP asymmetry in these decays using data from the BABAR detector, providing new experimental insights.

Contribution

It presents the first measurements of decay rate ratios and CP asymmetry for B- --> D*0 K- decays with the BABAR detector, expanding understanding of these processes.

Findings

Measured R*(CP+)=0.088+-0.021 (stat) +0.007-0.005 (syst)

Measured R*(non-CP)=0.0805+-0.0040 (stat)+-0.0039-0.0032 (syst)

CP asymmetry A*(CP+)= -0.02+-0.24 (stat)+-0.05 (syst)

Abstract

We present a study of the decays B- --> D*0 pi- and B- --> D*0 K-, where the D*0 decays into D0 pi0, with the D0 reconstructed in the CP eigenstates K- K+ and pi- pi+ and in the (non-CP) channels K- pi+, K- pi+ pi+ pi-, and K- pi+ pi0. We use an unbinned maximum likelihood fit to measure the signal yields. Using a sample of about 123 million Y(4S) decays into B anti-B pairs, we measure the ratios of decay rates R*(CP+)=BR(B- --> D*0(CP+) K-)/BR(B- --> D*0(CP+) pi-) = 0.088+-0.021(stat)+0.007-0.005(syst), and provide the first measurements of R*(non-CP) = BR(B- --> D*0(non-CP) K-)/BR(B- --> D*0(non-CP) pi-) = 0.0805+-0.0040(stat)+0.0039-0.0032(syst), and of the CP asymmetry A*(CP+) = (BR(B- --> D*0(CP+) K-)-BR(B+ --> D*0(CP+) K+))/(BR(B- --> D*0(CP+) K-)+BR(B+ --> D*0(CP+) K+)) = -0.02+-0.24(stat)\+-0.05(syst). These results are preliminary.