Evidence for CP violation in B0->J/Psi pi0 decays

TL;DR

This paper reports the first significant evidence of CP violation in B0->J/Psi pi0 decays, measuring CP asymmetries and branching fractions with high statistical significance.

Contribution

It provides the first measurement of CP violation parameters in B0->J/Psi pi0 decays, demonstrating CP violation beyond previous observations.

Findings

CP asymmetry parameter S=-1.23 ± 0.21 ± 0.04

Branching fraction B(B0->J/Psi pi0)=(1.69 ± 0.14 ± 0.07)×10^{-5}

Measured S value is 4.0 standard deviations from zero

Abstract

We present measurements of the branching fraction and time-dependent CP asymmetries in B0->J/Psi pi0 decays based on 466 million Y(4S)->BBbar events collected with the BaBar detector at the SLAC PEP-II asymmetric-energy B factory. We measure the CP asymmetry parameters S=-1.23 +/- 0.21 +/- 0.04 and C=-0.20 +/- 0.19 +/- 0.03, where the measured value of S is 4.0 standard deviations from zero including systematic uncertainties. The branching fraction is determined to be B(B0->J/Psi pi0)=(1.69 +/- 0.14 +/- 0.07)*10^{-5}.