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تسجيل مستخدم جديدAnomaly free Froggatt-Nielsen models of flavor
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We introduce two anomaly fr
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We present a doubly parametric extension of the standard Froggatt--Nielsen (FN) mechanism. As is well known, mass matrices of the up- and down-type quark sectors and the charged lepton sector in the standard model can be parametrized well by a parame
ter $lambda$ which is usually taken to be the sine of the Cabibbo angle ($lambda = sintheta_text{C} simeq 0.225$). However, in the neutrino sector, there is still room to realize the two neutrino mass squared differences $Delta m_text{sol}^2$ and $Delta m_text{atm}^2$, two large mixing angles $theta _{12}$ and $theta _{23}$, and non-zero $theta _{13}$. Then we consider an extension with an additional parameter $rho$ in addition to $lambda$. Taking the relevant FN charges for a power of $lambda~(=0.225)$ and additional FN charges for a power of $rho$, which we assume to be less than one, we can reproduce the ratio of the two neutrino mass squared differences and three mixing angles. In the normal neutrino mass hierarchy, we show several patterns for taking relevant FN charges and the magnitude of $rho$. We find that if $sin theta_{23}$ is measured more precisely, we can distinguish each pattern. This is testable in the near future, for example in neutrino oscillation experiments. In addition, we predict the Dirac CP-violating phase for each pattern.
We study UV-complete Froggatt-Nielsen-like models for the generation of mass and mixing hierarchies, assuming that the integrated heavy fields are chiral with respect to an abelian Froggatt-Nielsen symmetry. It modifies the mixed anomalies with respe
ct to the Standard Model gauge group, which opens up the possibility to gauge the Froggatt-Nielsen symmetry without the need to introduce additional spectator fermions, while keeping mass matrices usually associated to anomalous flavour symmetries. We give specific examples where this happens, and we study the flavourful axion which arises from an accidental Peccei-Quinn symmetry in some of those models. Such an axion is typically more coupled to matter than in models with spectator fermions.
We propose UV-completions of Froggatt-Nielsen-Peccei-Quinn models of fermion masses and mixings with flavored axions, by incorporating heavy fields. Here, the $U(1)$ Froggatt-Nielsen symmetry is identified with the Peccei-Quinn symmetry to solve the
strong CP problem along with the mass hierarchies of the Standard Model fermions. We take into account leading order contributions to the fermion mass matrices giving rise to Nearest-Neighbour-Interaction structure in the quark sector and $A_2$ texture in the neutrino sector. A comprehensive numerical analysis has been performed for the fermion mass matrices. Subsequently, we investigate the resulting axion flavor violating couplings and the axion-photon coupling arising from the model.
We study how to incorporate CP violation in the Froggatt--Nielsen (FN) mechanism. To this end, we introduce non-renormalizable interactions with a flavor democratic structure to the fermion mass generation sector. It is found that at least two iso-si
nglet scalar fields with imposed a discrete symmetry are necessary to generate CP violation due to the appearance of the relative phase between their vacuum expectation values. In the simplest model, ratios of quark masses and the Cabibbo-Kobayashi-Maskawa (CKM) matrix including the CP violating phase are determined by the CKM element |V_{us}| and the ratio of two vacuum expectation values R=|R|e^{i*alpha} (a magnitude and a phase). It is demonstrated how the angles phi_i (i=1--3) of the unitarity triangle and the CKM off-diagonal elements |V_{ub}| and |V_{cb}| are predicted as a function of |V_{us}|, |R| and alpha. Although the predicted value of the CP violating phase does not agree with the experimental data within the simplest model, the basic idea of our scenario would be promising to construct a more realistic model of flavor and CP violation.
We study Froggatt-Nielsen (FN) like flavor models with modular symmetry. The FN mechanism is a convincing solution to the flavor puzzle in quark sector. The FN mechanism requires an extra $U(1)$ gauge symmetry which is broken at high energy. Alternat
ively, in the framework of modular symmetry the modular weights can play the role of the FN charges of the extra $U(1)$ symmetry. Based on the FN-like mechanism with modular symmetry we present new flavor models for quark sector. Assuming that the three generations have a common representation under modular symmetry, our models simply reproduce the FN-like Yukawa matrices. We also show that the realistic mass hierarchy and mixing angles, which are related each other through the modular parameters and a scalar vev, can be realized in models with several finite modular groups (and their double covering groups) without unnatural hierarchical parameters.
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