量測Bs介子至K+K-介子之稀有二體衰變

Abstract

We report measurements of Bs → hh decays, where h stands for a charged or neutral kaon, or a charged pion. These results are obtained using a data sample of 23.6 fb−1 containing 1.25 million B∗sB∗s events collected at theΥ(5S ) resonance at the KEKB asymmetric energy e+e− collider. We observe the decay Bs → K+ K− and measure its branching fraction, B(Bs → K + K − ) = [3.8 +1.0 −0.9 (stat) ±0.7(syst)] ×10−5 . No significant signals are seen in other decay modes and we set upperlimits at 90% confidence level: B(Bs → K−π+) < 1.2 × 10−5 , B(Bs → π+π− ) < 2.6 × 10 −5 and B(Bs → K0K0 ) < 6.6 × 10 −5.