PNNL

Abstract

We report a measurement of the CP-violation parameter sin2?1 at the ?(5S) resonance using a new tagging method, called “B-p tagging.” In ?(5S) decays containing a neutral B meson, a charged B, and a charged pion, the neutral B is reconstructed in the J/?KS0 CP-eigenstate decay channel. The initial flavor of the neutral B meson at the moment of the ?(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-p+ and B-p- tagged J/?KS0 yields, we determine sin2?1=0.57±0.58(stat)±0.06(syst). The results are based on 121??fb-1 of data recorded by the Belle detector at the KEKB e+e- collider.