Eur Phys J C (2004) 33: s370-s372
https://doi.org/10.1140/epjcd/s2004-03-1641-1

PS03 CP Violation

Belle studies of CP violation in B→π π decays

Institute of Particle and Nuclear Studies, KEK 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan

Received: 7 November 2003
Accepted: 6 January 2004
Published online: 6 February 2004

Abstract

A measurement of CP violating asymmetries in B ⁰ → π ⁺ π ^– decays in a data sample of 78 fb^–1 is presented. The data are taken on Υ(4S) resonance with the Belle detector in the KEKB asymmetry e ⁺ e ^– collider. A time-dependent analysis is performed for 740 reconstructed B ⁰ → π ⁺ π ^– candidates and the CP violation parameters are obtained to be A _{π π} = +0.77 ± 0.27 ± 0.08 and S _{π π} = –1.23 ± 0.41 ^+0.08 _–0.07. The result rules out the CP-conservation hypothesis (A _{π π} =0, S _{π π} =0) at 3.4σ.

PACS: 11.30.Er – 12.15.Hh – 13.25.Hw