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arXiv 0904.1341hep-ph
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推广的Friedberg Lee四代隐对称性、夸克质量和CP破坏

Extended Friedberg Lee hidden symmetries, quark masses and CP-violation with four generations

Shaouly Bar-Shalom, David Oaknin, Amarjit Soni

摘要:

部分地由于B和B_s衰变中的CP不对称性所引起的几个反常现象,我们考虑了具有第四个序列族的标准模型(SM_4),它似乎提供了一个相当简单的解决方案。我们首先假设T不变性,将上夸克和下夸克4x 4质量矩阵取为实数。遵循Friedberg和Lee(FL)的方法,我们对未观测到的(“隐藏的”)上夸克和下夸克SU(2)态施加了“隐藏的”对称性。四代的隐藏对称性确保了两个零质量本征态的存在,我们将其分别视为上夸克扇区和下夸克扇区中的(u,c)和(d,s)态。然后,我们同时打破T-不变性和隐藏的对称性,通过引入两个相位因子在每个部门。这种破缺机制产生了小夸克质量m_u、m_c和m_d、m_s,它们与隐藏对称的方向一起决定了SM 4中CP破坏的大小。为了说明,我们选择了一个特定的物理图像的隐藏的对称性和破缺机制,再现所观察到的夸克质量,混合角和CP破坏,并在同一时间,使我们能够进一步获得非常有趣的关系/预测的混合角t和t '。例如,通过这种选择,我们得到V_{td} ~(V_{cb} / V_{cd} - V_{ts} / V_{us})+ O(λ^2)和V_{t'b} ~ V_{t'd} x(V_{cb} / V_{cd}),V_{tb'} ~ V_{t'd} x(V_{ts} / V_{us}),这意味着V_{t'd} > V_{t'b},V_{tb'}。我们还发现Cabibbo角与隐对称性的方向有关,并且我们模型在高能时的关键CP破坏量J_{SM4} = Im[ V_{tb} V_{t'b} ^* V_{t'b'} V_{tb'} ^*]是SM的Jarlskog不变量的高能模拟,与光夸克质量和测量的CKM角成正比。

英文摘要:

Motivated in part by the several observed anomalies involving CP asymmetries of B and B_s decays, we consider the Standard Model with a 4th sequential family (SM4) which seems to offer a rather simple resolution. We initially assume T-invariance by taking the up and down-quark 4x4 mass matrix to be real. Following Friedberg and Lee (FL), we then impose a "hidden" symmetry on the unobserved ("hidden") up and down-quark SU(2) states. The hidden symmetry for four generations ensures the existence of two zero-mass eigenstates, which we take to be the (u,c) and (d,s) states in the up and down-quark sectors, respectively. Then, we simultaneously break T-invariance and the hidden symmetry by introducing two phase factors in each sector. This breaking mechanism generates the small quark masses m_u, m_c and m_d, m_s which, along with the orientation of the hidden symmetry, determine the size of CP-violation in the SM4. For illustration we choose a specific physical picture for the hidden symmetry and the breaking mechanism that reproduces the observed quark masses, mixing angles and CP-violation, and at the same time allows us to further obtain very interesting relations/predictions for the mixing angles of t and t'. For example, with this choice we get V_{td} ~ (V_{cb}/V_{cd} - V_{ts}/V_{us}) + O(λ^2) and V_{t'b} ~ V_{t'd}x(V_{cb}/V_{cd}), V_{tb'} ~ V_{t'd}x(V_{ts}/V_{us}), implying that V_{t'd} > V_{t'b},V_{tb'}. We furthermore find that the Cabibbo angle is related to the orientation of the hidden symmetry and that the key CP-violating quantity of our model at high-energies, J_{SM4} = Im[V_{tb} V_{t'b}^* V_{t'b'} V_{tb'}^*], which is the high-energy analogue of the Jarlskog invariant of the SM, is proportional to the light-quark masses and the measured CKM angles.

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