基於KEKB不對稱能量電子正子對撞器在Υ(5S)能量下所收集之23.6fb-1資料,我們對Bs介子的稀有二體衰變進行分析,其中包含K+K-, K-π+,π+π-, K0K0。 我們以5.8個標準差的信心水準觀測到Bs至K+K-的衰變。我們量測到其衰變機率(B)為: B(Bs -> K+K-) = [3.8 +1.0 -0.9(stat.)±0.7(sys.)]×10-5 另外,因未有明顯訊號,我們給予90%信心水準的衰變機率(B)上限: B(Bs -> K-π+) < 1.2×10-5 B(Bs ->π+π-) < 2.6×10-5 B(Bs -> K0K0) < 6.6×10-5
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.