Measurement of Time-Dependent CP-Violating Asymmetries and Constraints on sin(2 beta+gamma) with Partial Reconstruction of B->D*-+pi+- Decays

TL;DR

This paper measures CP-violating asymmetries in B meson decays to constrain the value of sin(2beta+gamma), using partial reconstruction techniques on a large dataset from the BABAR experiment.

Contribution

It introduces a novel partial reconstruction method to measure time-dependent CP asymmetries in B decays, providing new constraints on sin(2beta+gamma).

Findings

Measured parameters a_D*pi and c_l_D*pi with uncertainties.

Established lower limits on | abla(2beta+gamma)| at 68% and 90% confidence levels.

Used partial reconstruction to analyze a large dataset of B decays.

Abstract

We present a measurement of the time-dependent CP-violating asymmetries in decays of neutral B mesons to the final states D*-+ pi+-, using approximately 232 million BBbar events recorded by the BABAR experiment at the PEP2 e+e- storage ring. Events containing these decays are selected with a partial reconstruction technique, in which only the high-momentum pi+- from the B decay and the low-momentum pi-+ from the D*-+ decay are used. % We measure the parameters related to 2beta+gamma to be a_D*pi=-0.034 +- 0.014 +- 0.009 and c_l_D*pi = -0.019 +- 0.022 +- 0.013. With some theoretical assumptions, we interpret our results in term of the lower limits |\sin(2beta+gamma)|> 0.62 (0.35) at 68% (90%) confidence level.