Measurements of time-dependent CP asymmetries in B0 --> D(*)+D(*)- decays

TL;DR

This paper reports new measurements of time-dependent CP asymmetries in B0 decays to D(*)+D(*)- using a large dataset, providing results consistent with the Standard Model and improving understanding of CP violation.

Contribution

First measurement of multiple CP asymmetries in B0 --> D(*)+D(*)- decays with high precision using BaBar data.

Findings

CP-odd fraction R_perp = 0.158 +/- 0.028 +/- 0.006

CP asymmetry parameters for CP-even component: S_+ = -0.76 +/- 0.16 +/- 0.04, C_+ = 0.00 +/- 0.12 +/- 0.02

All measured asymmetries are consistent with the Standard Model.

Abstract

We present new measurements of time-dependent CP asymmetries for B0 --> D(*)+D(*)- decays using (467 +/- 5) X 10^6 BB pairs collected with the BaBar detector located at the PEP-II B Factory at the Stanford Linear Accelerator Center. We determine the CP-odd fraction of the B0 --> D*+D*- decays to be R_perp = 0.158 +/- 0.028 +/- 0.006 and find CP asymmetry parameters for the CP-even component of the decay S_+ = -0.76 +/- 0.16 +/- 0.04 and C_+ = 0.00 +/- 0.12 +/- 0.02. We measure S = -0.63 +/- 0.36 +/- 0.05 and C = -0.07 +/- 0.23 +/- 0.03 for B0 --> D+D-, S = -0.62 +/- 0.21 +/- 0.03 and C = 0.08 +/- 0.17 +/- 0.04 for B0 --> D*+D-$, and S = -0.73 +/- 0.23 +/- 0.05 and C = 0.00 +/- 0.17 +/- 0.03 for B0 --> D+D*-. For the B0 --> D*+/-D-/+ decays, we also determine the CP-violating asymmetry A = 0.008 +/- 0.048 +/- 0.013. In each case, the first uncertainty is statistical and the second is systematic. The measured values for the asymmetries are all consistent with the Standard Model.