Measurements of CP-Violating Asymmetries in B0 to a1(1260)^{+-} pi^{-+} Decays

TL;DR

This paper reports measurements of CP-violating asymmetries in B0 decays to a1(1260) pi, providing insights into CP violation and the CKM angle alpha using data from the BaBar experiment.

Contribution

First measurement of CP asymmetries in B0 to a1(1260) pi decays, extracting the effective CKM angle alpha with data from 384 million B meson pairs.

Findings

Measured CP asymmetry A^{a1pi}_{CP} = -0.07 +- 0.07 +- 0.02

Determined mixing-induced CP violation S_{a1pi} = 0.37 +- 0.21 +- 0.07

Estimated alpha_{eff} = 78.6^{0} +- 7.3^{0}

Abstract

We present measurements of CP-violating asymmetries in the decay B0 -> a_1(1260)^{+-} pi^{-+} with a_1(1260)^{+-} -> pi^{-+} pi^{+-} pi^{+-}. The data sample corresponds to 384 million B B-bar pairs collected with the BaBar detector at the PEP-II asymmetric B-factory at SLAC. We measure the CP-violating asymmetry A^{a1pi}_{CP}=-0.07+-0.07+-0.02, the mixing-induced CP violation parameter S_{a1pi}= 0.37 +-0.21+-0.07, the direct CP violation parameter C_{a1pi}=-0.10+-0.15+-0.09, and the parameters DeltaC_{a1pi}=0.26+-0.15+-0.07 and DeltaS_{a1pi}=-0.14+-0.21+-0.06. From these measured quantities we exstract the angle alpha_{eff}= 78.6^{0} +- 7.3^{0}.