美介子无粲两体衰变γ和-2 β_s的测定
Determination of gamma and -2beta_s from charmless two-body decays of beauty mesons
摘要：
利用LHCb对B^0_s -> K^+K^-衰变中与时间相关的CP破坏的最新测量，B^0_s -> K^+K^-和B^0 -> π^+π^-衰变过程的衰变幅度之间的U自旋关系允许对幺正三角形的角γ和B^0_s混合相位-2_s施加约束。本文还介绍了一种扩展方法的结果，该方法使用了来自其他实验的B^0 -> π^0π^0和B^+ -> π^+π^0衰变的额外输入，并利用了同位旋对称性。研究了结果与最大允许U自旋断裂量的关系。在68%的概率下，确定值γ=（63.5 + 7.2 - 6.7）度模180度。在另一种分析中，得到了-2_s = -0.12 +0.14-0.16rad的值，在这两种测量中，由于U-自旋破碎效应引起的不确定度高达50%。
英文摘要：
Using the latest LHCb measurements of time-dependent CP violation in the B^0_s -> K^+K^- decay, a U-spin relation between the decay amplitudes of B^0_s -> K^+K^- and B^0 -> π^+π^- decay processes allows constraints to be placed on the angle gamma of the unitarity triangle and on the B^0_s mixing phase -2β_s. Results from an extended approach, which uses additional inputs on B^0 -> π^0π^0 and B^+ -> π^+π^0 decays from other experiments and exploits isospin symmetry, are also presented. The dependence of the results on the maximum allowed amount of U-spin breaking is studied. At 68% probability, the value γ= ( 63.5 +7.2 -6.7 ) degrees modulo 180 degrees is determined. In an alternative analysis, the value -2β_s = -0.12 +0.14 -0.16 rad is found. In both measurements, the uncertainties due to U-spin breaking effects up to 50% are included.
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