CP Violation in B_d \to D^+D^-, D^{*+}D^-, D^+D^{*-} and D^{*+}D^{*-} Decays

TL;DR

This paper investigates CP asymmetries in specific B_d meson decays, highlighting the roles of short-distance penguin mechanisms and final-state rescattering, with numerical estimates of CP violation magnitudes and implications for testing the factorization hypothesis.

Contribution

It provides a detailed analysis of CP violation in B_d decays using factorization and isospin relations, including updated numerical estimates and insights into weak phase determination.

Findings

Direct CP asymmetry in B^0_d d ar{B}^0_d d D^+D^- can reach 3%

CP-even and CP-odd contributions in B^0_d d ar{B}^0_d d D^{*+}D^{*-} are 89% and 11%

Final-state rescattering can modify indirect CP asymmetries

Abstract

CP asymmetries in B_d \to D^+D^-, D^{*+}D^-, D^+D^{*-} and D^{*+}D^{*-} decays are investigated with the help of the factorization approximation and isospin relations. We find that the direct CP violation is governed only by the short-distance penguin mechanism, while the indirect CP asymmetries in B_d \to D^{\pm}D^{*\mp} transitions may be modified due to the final-state rescattering effect. An updated numerical analysis shows that the direct CP asymmetry in B^0_d vs \bar{B}^0_d \to D^+D^- decays can be as large as 3%. The CP-even and CP-odd contributions to the indirect CP asymmetry in B^0_d vs \bar{B}^0_d \to D^{*+}D^{*-} decays are found to have the rates 89% and 11%, respectively. Some comments on the possibilities to determine the weak phase \beta and to test the factorization hypothesis are also given.