We report a measurement of the CP-violation parameter sin2φ1 at the Υ(5S) resonance using a new tagging method, called "B-π tagging." In Υ(5S) decays containing a neutral B meson, a charged B, and a charged pion, the neutral B is reconstructed in the J/ψKS0 CP-eigenstate decay channel. The initial flavor of the neutral B meson at the moment of the Υ(5S) decay is opposite to that of the charged B and may thus be inferred from the charge of the pion without reconstructing the charged B. From the asymmetry between B-π+ and B-π- tagged J/ψKS0 yields, we determine sin2φ1=0.57±0.58(stat) ±0.06(syst). The results are based on 121fb-1 of data recorded by the Belle detector at the KEKB e+e- collider.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)