Study of Time-Dependent CP Asymmetries with Partial Reconstruction of B -> D*+ pi-

TL;DR

This paper reports a preliminary measurement of time-dependent CP asymmetries in neutral B meson decays to D*pi final states using partial reconstruction, providing insights into the unitarity triangle angles.

Contribution

It introduces a partial reconstruction method for measuring CP asymmetries in B decays and interprets results to constrain unitarity triangle angles.

Findings

Measured CP asymmetry A = -0.063 +/- 0.024 (stat.) +/- 0.017 (syst.)

Set a bound on |sin(2 beta + gamma)| based on the results

Demonstrated effectiveness of partial reconstruction in CP violation studies

Abstract

We present a preliminary measurement of the time-dependent CP asymmetries in decays of neutral B mesons to the final states D*pi using approximately 82 million BBbar events collected by the BaBar experiment at the PEPII storage ring. Events containing these decays are selected with a partial reconstruction technique, in which only the high momentum pion and the low momentum pion from the D* decay are reconstructed. The flavor of the other B meson in the event is tagged using the information from kaon and lepton candidates. We measure the time-dependent CP asymmetry A = -0.063 +/- 0.024 (stat.) +/- 0.017 (syst.). We interpret these results in terms of the angles of the unitarity triangle to set a bound on |sin(2 beta + gamma)|.