Measurement of Branching Fractions and CP-Violating Charge Asymmetries for B Meson Decays to D(*)D(*), and Implications for the CKM Angle gamma

TL;DR

This paper reports precise measurements of B meson decay rates and charge asymmetries to D(*)D(*) modes, providing insights into CP violation and constraining the CKM angle gamma, using data from the BaBar experiment.

Contribution

First comprehensive measurement of branching fractions and CP asymmetries for B to D(*)D(*) decays, with implications for the CKM angle gamma.

Findings

Branching fractions measured with statistical and systematic uncertainties.

Charge asymmetries consistent with no CP violation within errors.

CKM angle gamma constrained to a specific range at 68% confidence level.

Abstract

We present measurements of the branching fractions and charge asymmetries of B decays to all D(*)D(*) modes. Using 232 million BBbar pairs recorded on the Upsilon(4S) resonance by the BaBar detector at the e+e- asymmetric B factory PEP-II at the Stanford Linear Accelerator Center, we measure the branching fractions BF(B0 -> D*+D*-) = (8.1 +- 0.6 +- 1.0) x 10^-4, BF(B0 -> D*+-D-+) = (5.7 +- 0.7 +- 0.7) x 10^-4, BF(B0 -> D+D-) = (2.8 +- 0.4 +- 0.5) x 10^-4, BF(B+ -> D*+D*0) = (8.1 +- 1.2 +- 1.2) x 10^-4, BF(B+ -> D*+D0) = (3.6 +- 0.5 +- 0.4) x 10^-4, BF(B+ -> D+D*0) = (6.3 +- 1.4 +- 1.0) x 10^-4, and BF(B+ -> D+D0) = (3.8 +- 0.6 +- 0.5) x 10^-4, where in each case the first uncertainty is statistical and the second systematic. We also determine the limits BF(B0 -> D*0D*0) < 0.9 x 10^-4, BF(B0 -> D*0D0) < 2.9 x 10^-4, and BF(B0 -> D0D0) < 0.6 x 10^-4, each at 90% confidence level. All decays above denote either member of a charge conjugate pair. We also determine the CP-violating charge asymmetries A(B0 -> D*+-D-+) = 0.03 +- 0.10 +- 0.02, A(B+ -> D*+D*0) = -0.15 +- 0.11 +- 0.02, A(B+ -> D*+D0) = -0.06 +- 0.13 +- 0.02, A(B+ -> D*+D*0) = 0.13 +- 0.18 +- 0.04, and A(B+ -> D+D0) = -0.13 +- 0.14 +- 0.02. Additionally, when we combine these results with information from time-dependent CP asymmetries in B0 -> D*+D*- decays and world-averaged branching fractions of B decays to Ds(*)D(*) modes, we find the CKM phase gamma is favored to lie in the range [0.07-2.77] radians (with a +0 or +pi radians ambiguity) at 68% confidence level.