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Register a new userFlavor Non-universal Pati-Salam Unification and Neutrino Masses
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We analyze the neutrino mass spectrum and discuss the extra-dimensional interpretation of a three-site Pati-Salam model which i) unifies all families of quark and leptons, ii) provides a natural description of the Standard Model Yukawa couplings, iii) could account for the recent $B$-physics anomalies. The key feature of the model is a breaking of the Pati-Salam and electroweak gauge symmetries localized on opposite sites, communicated to the other sites in an attenuated manner via nearest-neighbor interactions. We show that in this context gauge-singlet fermions localized on each site, receiving hierarchical Majorana masses, can allow the implementation of an inverse seesaw mechanism leading to light anarchic neutrino masses consistent with data. The continuum limit of this three-site setup has a natural interpretation in terms of a warped extra dimension with three defects, where the required exponential hierarchies can be achieved from $mathcal{O}(1)$ differences in the bulk field masses.
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We implement the mechanism of non-thermal leptogenesis in the framework of an inflationary model based on a supersymmetric (SUSY) Pati-Salam Grand Unified Theory (GUT). In particular, we show that inflation is driven by a quartic potential associated with the Higgs fields involved in the spontaneous GUT symmetry breaking, in the presence of a non-minimal coupling of the inflaton field to gravity. The inflationary model relies on renormalizable superpotential terms and does not lead to overproduction of magnetic monopoles. It is largely independent of one-loop radiative corrections, and it can be consistent with current observational data on the inflationary observables, with the GUT symmetry breaking scale assuming its SUSY value. Non-thermal leptogenesis is realized by the out-of-equilibrium decay of the two lightest right-handed (RH) neutrinos, which are produced by the inflaton decay. Confronting our scenario with the current observational data on light neutrinos, the GUT prediction for the heaviest Dirac neutrino mass, the baryon asymmetry of the universe and the gravitino limit on the reheating temperature, we constrain the masses of the RH neutrinos in the range (10^10-10^15) GeV and the Dirac neutrino masses of the two first generations to values between 0.1 and 20 GeV.
We provide what we believe is the minimal three family ${cal N} = 1$ SUSY and conformal Pati-Salam Model from type IIB superstring theory. This $Z_3$ orbifolded AdS$otimes S^5$ model has long lived protons and has potential phenomenological consequences for LHC.
In this paper, we consider a lopsided flavor texture compatible with thermal leptogenesis in partially composite Pati--Salam unification. The Davidson--Ibarra bound $M_{ u R1} gtrsim 10^9$ GeV for the successful thermal leptogenesis can be recast to the Froggatt--Nielsen (FN) charge of the lopsided texture. We found the FN charge $n_{ u1}$ of the lightest right-handed neutrino $ u_{R1}$ can not be larger than a upper bound, $n_{ u1} lesssim 4.5$. From the viewpoint of unification, the FN charges of the neutrinos $n_{ u i}$ should be the same to that of other SM fermions. Then, two cases $n_{ u i} = n_{qi} = (3,2,0)$ and $ n_{ u i} = n_{l i} = (n+1,n,n)$ are considered. Observations of PS model shows that the case of $n=0$, $n_{li} = n_{di} = (1,0,0)$ will be the simplest realization. To decrease the FN charges of these fermions from the GUT invariant FN charges $n_{qi} = (3,2,0)$, we utilize the partial compositeness. In this picture, the hierarchies of Yukawa matrices are a consequence of mixings between massless chiral fermions $f_{L}, f_{R}$ and massive vector fermions $F_{L,R}, F_{L,R}$. This is induced by the linear mixing terms $lambda^{f} bar f_{L} F_{R}$ and $lambda^{f} bar F_{L} f_{R}$. As a result of the partial compositeness, the decreases of FN charges require fine-tunings between mass and Yukawa matrices either for the increases of $lambda^{f, f}$ or for the decreases of $M_{F,F}$. Therefore, the case for $n=2$ and $n_{di} = n_{li} = (3,2,2)$, which requires only increases of FN charges will be appropriate to build a natural model.
We analyze the phenomenological consequences of embedding a flavor symmetry based on the groups $A_5$ and CP in a supersymmetric framework. We concentrate on the leptonic sector, where two different residual symmetries are assumed to be conserved at LO for charged and neutral leptons. All possible realizations to generate neutrino masses at tree level are investigated. Sizable flavor violating effects in the charged lepton sector are unavoidable due to the non-universality of soft-breaking terms determined by the symmetry. We derive testable predictions for the neutrino spectrum, lepton mixing and flavor changing processes with non-trivial relations among observables.
Composite Higgs models can be extended to the Planck scale by means of the partially unified partial compositeness (PUPC) framework. We present in detail the Techni-Pati-Salam model, based on a renormalizable gauge theory $SU(8)_{PS}times SU(2)_Ltimes SU(2)_R$. We demonstrate that masses and mixings for all generations of standard model fermions can be obtained via partial compositeness at low energy, with four-fermion operators mediated by either heavy gauge bosons or scalars. The strong dynamics is predicted to be that of a confining $Sp(4)_{rm HC}$ gauge group, with hyper-fermions in the fundamental and two-index anti-symmetric representations, with fixed multiplicities. This motivates for Lattice studies of the Infra-Red near-conformal walking phase, with results that may validate or rule out the model. This is the first complete and realistic attempt at providing an Ultra-Violet completion for composite Higgs models with top partial compositeness. In the baryon-number conserving vacuum, the theory also predicts a Dark Matter candidate, with mass in the few TeV range, protected by semi-integer baryon number.
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