Simultaneous extraction of the Fermi constant and PMNS matrix elements in the presence of a fourth generation
Simultaneous extraction of the Fermi constant and PMNS matrix elements in the presence of a fourth generation
复制标题
在第四代存在的情况下同时提取费米常数和 PMNS 矩阵元素
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
CKMfitter Group
中科院分区：
文献类型：
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作者：
H. Lacker;A. Menzel;CKMfitter Group
最近对第四代夸克和轻子的约束进行的几项研究都受到了中微子区域前三代夸克和轻子3×3统一性的临时假设的影响。只有在这种假设下，人们才能从μ子寿命测量中确定费米常数GF，其声称的精度为GF = 1.16637(1) × 10−5 GeV−2。我们研究如何在四代框架内从轻子和辐射 μ 和 τ 衰变以及 Kℓ3 衰变和带电介子的轻子衰变中提取 GF，并讨论轻子普适性测试在这种情况下的作用。在轻子和辐射 μ 和 τ 衰变、Kℓ3 衰变和带电 π 介子轻子衰变的组合拟合中，我们发现第四代矩阵元素 |Ue4| 的 p 值为 2.6% = 0 中微子混合矩阵。我们强调，如果同时考虑这三个部分，则只能以一致的方式获得夸克和轻子味可观测量以及电弱精密可观测量对第四代的约束。
Several recent studies performed on constraints of a fourth generation of quarks and leptons suffer from the ad-hoc assumption that 3 × 3 unitarity holds for the first three generations in the neutrino sector. Only under this assumption is one able to determine the Fermi constant GF from the muon lifetime measurement with the claimed precision of GF = 1.16637(1) × 10−5 GeV−2. We study how well GF can be extracted within the framework of four generations from leptonic and radiative μ and τ decays, as well as from Kℓ3 decays and leptonic decays of charged pions, and we discuss the role of lepton universality tests in this context. In the combined fit to leptonic and radiative μ and τ decays, Kℓ3 decays and leptonic decays of charged pions we find a p-value of 2.6 % for the fourth generation matrix element |Ue4| = 0 of the neutrino mixing matrix. We emphasize that constraints on a fourth generation from quark and lepton flavour observables and from electroweak precision observables can only be obtained in a consistent way if these three sectors are considered simultaneously.