Measurement of Time-Dependent CP Asymmetries and the CP-Odd Fraction in the Decay B0->D*+D*-

TL;DR

This paper reports an updated measurement of CP asymmetries and the CP-odd fraction in B0 to D*+D*- decays, using a large data sample from the BaBar experiment, testing Standard Model predictions.

Contribution

It provides the first precise measurement of time-dependent CP asymmetries and the CP-odd fraction in B0 to D*+D*- decays with a large dataset, refining previous results.

Findings

CP-odd fraction measured as 0.125 ± 0.044 (stat) ± 0.007 (syst)

CP asymmetry parameter C+ measured as 0.06 ± 0.17 (stat) ± 0.03 (syst)

CP asymmetry parameter S+ measured as -0.75 ± 0.25 (stat) ± 0.03 (syst)

Abstract

We present an updated measurement of time-dependent \CP asymmetries and the \CP-odd fraction in the decay $B^0 \to D^{*+}D^{*-}$ using $232 \times 10^{6} \BB$ pairs collected by the \babar detector at the PEP-II $B$ factory. We determine the \CP-odd fraction to be $0.125 \pm 0.044\stat \pm 0.007\syst$. The time-dependent \CP asymmetry parameters $C_+$ and $S_+$ are determined to be $0.06\pm 0.17\stat \pm 0.03\syst$ and $-0.75 \pm 0.25\stat \pm 0.03\syst$, respectively. The Standard Model predicts these parameters to be 0 and $-\stwob$, respectively, in the absence of penguin amplitude contributions.