Division of High Energy Physics, Department of Physics, University of Helsinki, Finland.
Phys Rev Lett. 2011 Nov 11;107(20):201802. doi: 10.1103/PhysRevLett.107.201802. Epub 2011 Nov 8.
We report the first observation of the baryonic flavor-changing neutral current decay Λ(b)(0)→Λμ(+)μ(-) with 24 signal events and a statistical significance of 5.8 Gaussian standard deviations. This measurement uses a pp collisions data sample corresponding to 6.8 fb(-1) at √s = 1.96 TeV collected by the CDF II detector at the Tevatron collider. The total and differential branching ratios for Λ(b)(0)→Λμ(+)μ(-) are measured. We find B(Λ(b)(0)→Λμ(+)μ(-))=[1.73 ± 0.42(stat) ± (syst)] × 10(-6). We also report the first measurement of the differential branching ratio of B(s)(0)→ϕμ(+)μ(-), using 49 signal events. In addition, we report branching ratios for B(+)→K(+)μ(+)μ(-), B(0)→K(0)μ(+)μ(-), and B→K(*)(892)μ(+)μ(-) decays.
我们首次观察到了重子味变中性电流衰变 Λ(b)(0)→Λμ(+)μ(-)，共有 24 个事例，统计显著性为 5.8 个高斯标准偏差。该测量使用了 CDF II 探测器在 Tevatron 对撞机上采集的 1.96 TeV 的 pp 碰撞数据样本，对应于 6.8 fb(-1)。我们测量了 Λ(b)(0)→Λμ(+)μ(-)的总分支比和微分分支比。我们发现 B(Λ(b)(0)→Λμ(+)μ(-))=[1.73 ± 0.42(stat) ± (syst)] × 10(-6)。我们还首次测量了 B(s)(0)→ϕμ(+)μ(-)的微分分支比，使用了 49 个事例。此外，我们还报告了 B(+)→K(+)μ(+)μ(-)、B(0)→K(0)μ(+)μ(-)和 B→K(*)(892)μ(+)μ(-)衰变的分支比。
