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arXiv 0910.4845hep-lat
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Nf = 2的扭曲质量费米子的K介子和D介子半轻子衰变的矢量和标量形状因子

Vector and scalar form factors for K- and D-meson semileptonic decays from twisted mass fermions with Nf = 2

S. Di Vita, B. Haas, F. Mescia, V. Lubicz, S. Simula, C. Tarantino

摘要:

我们目前的形状因子相关的K -> π介子和D -> π介子半轻子衰变的晶格结果,从两种口味的动力学扭曲质量的费米子和π介子质量轻至260 MeV的模拟。对于K -> π介子衰变,我们讨论了系统不确定性的主要来源的估计,包括奇异夸克的猝灭,导致我们的最终结果f+(0)= 0.9560(57)(62)。结合最新的实验数据,我们的f+(0)的值意味着CKM矩阵元素|Vus|的值为0.2267(5)(20)与第一行CKM酉性一致。对于D -> π介子衰变,应用重介子手征微扰理论可以很好地外推我们在物理点上的标量和矢量形状因子的结果,得到与实验数据很好的一致性。特别是在零动量转移时,我们得到f+(0)= 0.64(5)。

英文摘要:

We present lattice results for the form factors relevant in the K -> pion and D -> pion semileptonic decays, obtained from simulations with two flavors of dynamical twisted-mass fermions and pion masses as light as 260 MeV. For K -> pion decays we discuss the estimates of the main sources of systematic uncertainties, including the quenching of the strange quark, leading to our final result f+(0) = 0.9560 (57) (62). Combined with the latest experimental data, our value of f+(0) implies for the CKM matrix element |Vus| the value 0.2267 (5) (20) consistent with the first-row CKM unitarity. For D -> pion decays the application of Heavy Meson Chiral Perturbation Theory allows to extrapolate our results for both the scalar and the vector form factors at the physical point with quite good accuracy, obtaining a nice agreement with the experimental data. In particular at zero-momentum transfer we obtain f+(0) = 0.64 (5).

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