Minimal Flavour Violation in its strong or weak versions, based on $U(3)^3$ and $U(2)^3$ respectively, allows suitable extensions of the Standard Model at the TeV scale to comply with current flavour constraints in the quark sector. Here we discuss considerations analogous to MFV in the context of $SU(5)$-unification, showing the new effects/constraints that arise both in the quark as in the lepton sector, where quantitative statements can be made controlled by the CKM matrix elements. The case of supersymmetry is examined in detail as a particularly motivated example. Third generation sleptons and neutralinos in the few hundred GeV range are shown to be compatible with current constraints.
We investigate the options for imposing flavor symmetries on a minimal renormalizable non-supersymmetric $\mathrm{SU}(5)$ grand unified theory, without introducing additional flavor-related fields. Such symmetries reduce the number of free parameters in the model and therefore lead to more predictive models. We consider the Yukawa sector of the Lagrangian, and search for all possible flavor symmetries. As a result, we find 25 distinct realistic flavor symmetry cases, with $\mathbb{Z}_2$, $\mathbb{Z}_3$, $\mathbb{Z}_4$, and $\mathrm{U}(1)$ symmetries, and no non-Abelian cases.
In the family grand unification models (fGUTs), we propose that gauge U(1)'s beyond the minimal GUT gauge group are family gauge symmetries. For the symmetry $L_μ-L_τ$, i.e. $Q_{2}-Q_{3}$ in our case, to be useful for the LHC anomaly, we discuss an SU(9) fGUT and also present an example in Georgi's SU(11) fGUT.
The unification of the quark and charged lepton flavor structures is revisited using the tools of Minimal Flavor Violation (MFV). Under that framework, we first identify a unique point in parameter space where flavor universality is maximally violated. Though from the point of view of the usual polynomial MFV expansions, standing close to that point would require unacceptable fine-tunings, it is automatically attained with infinite geometric MFV series. Remarkably, this peculiar point is precisely where the charged lepton Yukawa coupling can be expressed naturally in terms of those of the quar…
We study quark and lepton masses and mixings in a double covering of modular $A_4$ flavor symmetry in which we search for common solution of a single modulus $τ$, applying chi-square numerical analysis under the as minimum framework as possible. We have found the common region of $τ$ within $5σ$ interval that is narrow in case of normal hierarchy, but not found in case of inverted hierarchy.
Analyses of heavy mesons and baryons hadronic charmless decays using the flavor SU(3) symemtry can be formulated in two different forms. One is to construct the SU(3) irreducible representation amplitude (IRA) by decomposing effective Hamiltonian, and the other is to draw the topological diagrams (TDA). In the flavor SU(3) limit, we study various $B/D\to PP,VP,VV$, $B_c\to DP/DV$ decays, and two-body nonleptonic decays of beauty/charm baryons, and demonstrate that when all terms are included these two ways of analyzing the decay amplitudes are completely equivalent. Furthermore we clarify some…
We present a unified picture of flavor and electroweak symmetry breaking based on a nonlinear sigma model spontaneously broken at the TeV scale. Flavor and Higgs bosons arise as pseudo-Goldstone modes. Explicit collective symmetry breaking yields stable vacuum expectation values and masses protected at one loop by the little-Higgs mechanism. The coupling to the fermions generates well-definite mass textures--according to a U(1) global flavor symmetry--that correctly reproduce the mass hierarchies and mixings of quarks and leptons. The model is more constrained than usual little-Higgs models be…
Supersymmetry, local horizontal unification, and a solution to the flavor puzzle
具有局域水平对称性的超对称规范模型会产生由超对称破缺D项引起的大的变味中性流效应。我们展示了U（1）规范对称性的存在如何解决这个问题。然后我们构造了一个以SU（2）_H × U（1）_H为局域水平对称的现实规范模型，并提出U（1）_H因子可以等同于弦紧化引起的反常U（1）。这个模型解释了夸克质量和混合角之间的层次结构，自然地容纳太阳和大气中微子数据，并同时提供了一个解决超对称味问题。如果在当前一轮实验中没有观察到稀有衰变μ--> e γ，则可以排除该模型。
We show that one can explain the neutral and charged anomalies in B-meson decays in the minimal theory for quark-lepton unification.The implications for flavor violating processes are discussed in detail. Strikingly, experimental observations suggest that the unification of quarks and leptons could be realized below the ${\cal O}(10^2)$ TeV scale.
Quark-Lepton Unification and Lepton Flavor Non-Conservation from a TeV-scale Seesaw Neutrino Mass Texture
在最近的一篇论文中，我们指出轻中微子与重规范单重态的混合可以使来自e+e对撞机的Z极数据和来自费米实验室NuTeV实验的nu_mu（anti-nu_mu）散射数据相一致。我们还注意到，拟合数据所需的混合角比传统的跷跷板机制所预期的要大得多。在本文中，我们将展示如何通过明智地选择中微子质量纹理来安排这种混合。我们还认为，通过调用统一的狄拉克质量矩阵的上型夸克和中微子，重态的质量自然可以预期在几个TeV的范围。该模型受到轻子味变化过程μ-> e γ的强烈约束，该过程要求轻子普适性在带电通道中被破坏。
Recent neutrino oscillation experiments suggest that the PMNS matrix in the lepton sector has a $CP$ violating phase as the CKM matrix in the quark sector. However, origin of these phases in both matrices are not clarified by now. Although complex Yukawa couplings could induce these phases, they remain as free parameters of the model even in that case. If the $CP$ symmetry is considered to be spontaneously broken, they are expected to be determined by some physics at a much lower energy scale than the Planck scale. We study such a possibility in a framework of Pati-Salam type unification. We a…
