arXiv subjects

Zurab Tavartkiladze

Publications and source records attributed to Zurab Tavartkiladze.

At least 19 recordsLinked to original sources

arXiv2026

Fermion Mass Hierarchy and a High Quality Axion From Gauged U(1) Flavor Symmetry

We present a class of models based on a gauged $U(1)_F$ flavor symmetry that explains the hierarchical structure of fermion masses and mixings via the Froggatt-Nielsen (FN) mechanism, while also solving the strong CP problem by the Peccei-Quinn (PQ) mechanism. A global $U(1)_{\rm PQ}$ symmetry with a nonzero QCD anomaly emerges accidentally in this setup as a byproduct of the gauged $U(1)_F$ symmetry. The resulting axion is shown to be of high quality, with the axion potential safeguarded against quantum gravity corrections by the gauge symmetry. Three models, which are generalizations of the Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) axion model, are presented realizing this idea. The right-handed neutrino mass scale is identified as the Froggatt-Nielsen scale in these models. We present explicit UV completions of the FN sectors of these models and show that they preserve the high quality of the axion. In these models, the axion acts as a flavon field, leading to testable predictions in flavor-changing decays of neutral mesons. The axion also serves as the dark matter of the universe with the right amount of relic abundance without causing cosmological domain wall problems. Baryon asymmetry of the universe is realized via leptogenesis which is calculable in these models and found to be of the right order of magnitude.

hep-ph↗

arXiv2026

Minimal Modular Flavor Symmetry and Lepton Textures Near Fixed Points

An extension of the Standard Model with $Γ_2\simeq S_3$ modular flavor symmetry is presented. We consider the construction of the lepton sector, augmented by two right-handed neutrino states, in the vicinity of the fixed points $τ= i\infty $, $τ= i$ and $τ\!=\!ω\!=\!-\frac{1}{2}\!+\!i\frac{\sqrt{3}}{2}$. Due to the residual symmetries at these points, and with the aid of nonholomorphic modular forms (which constitute representations of $S_3$) and by assigning specific transformation properties to the fermion fields, highly economical models (without flavon fields) are constructed with interesting Yukawa textures. All presented models strongly prefer the inverted ordering for the neutrino masses.

hep-ph↗

arXiv2022

SM extension with a gauged flavor $U(1)_F$ symmetry

An extension of the Standard Model with anomaly free $U(1)_F$ flavor symmetry is studied in this paper. With this extension and the addition of the right-handed neutrino states, the solution of anomaly free charge assignments is found, which gives appealing texture zero and hierarchical Yukawa matrices. This gives us a natural understanding of the hierarchies between charged fermion masses and Cabibbo-Kobayashi-Maskawa (CKM) matrix elements. Neutrino Dirac and Majorana coupling matrices also have desirable structures leading to successful neutrino oscillations with inverted neutrino mass ordering. Other interesting implications of the presented scenario are also discussed.

hep-ph↗

arXiv2019

Chaotic Inflation from the MSSM Along Flat $D$-Term Trajectory

Within the MSSM we propose the chaotic inflationary scenario in which the inflaton field is a combination of sleptons and the Higgs field states evolving along the $D$-term flat direction. In the inflation and postinflation reheating processes, a decisive role is played by the MSSM Yukawa superpotential. The vacuum energy during the inflationary era is mainly from the muonic Yukawa coupling, while the inflaton decay and subsequent reheating process dominantly proceeds due to the strange quark Yukawa term. Because of these, the presented scenario is predictive and the results obtained agree well with cosmological observations. In particular, the scalar spectral index and the tensor-to-scalar ratio are respectively, $n_s\simeq 0.966$ and $r=0.00117$. The reheating temperature is found to be $T_r\simeq 7.2\times 10^7$ GeV.

hep-ph↗

arXiv2019

Higgs-Squark-Slepton Inflation from the MSSM

The inflation within the MSSM is proposed, where the inflaton field is a combination of the Higgs, squark and slepton states. While the inflationary phase is fully governed by the electron Yukawa superpotential coupling, the fields' condensates float along the flat $D$-term trajectory. This predicts the MSSM parameter $\tan β\simeq 13.1$ determined via the value of the curvature perturbation amplitude. The values of the scalar spectral index and the tensor-to-scalar ratio are predicted to be $n_s\simeq 0.966$ and $r=0.00118$. The postinflation reheating of the Universe proceeds by the radiative decay of the inflaton to the two gluons ($ϕ\to gg$) with the reheating temperature $T_r\simeq 1.4\cdot 10^7$ GeV.

hep-ph↗

arXiv2018

Light Pseudo-Goldstone Higgs Boson from SO(10) GUT with Realistic Phenomenology

Within the supersymmetric SO(10) grand unified theory (GUT), a new mechanism, giving the light Higgs doublet as a pseudo-Goldstone mode, is suggested. Realizing this mechanism, we present an explicit model with fully realistic phenomenology. In particular, desirable symmetry breaking and natural all-order hierarchy are achieved. The constructed model allows one to have a realistic fermion pattern, nucleon stability, and successful gauge coupling unification. The suggested mechanism opens prospects in the field for a novel $SO(10)$ GUT model building and for further investigations.

hep-ph↗

arXiv2018

Texture Zero Neutrino Models and Their Connection with Resonant Leptogenesis

Within the low scale resonant leptogenesis scenario, the cosmological CP asymmetry may arise by radiative corrections through the charged lepton Yukawa couplings. While in some cases, as one expects, decisive role is played by the $λ_{τ}$ coupling, we show that in specific neutrino textures only by inclusion of the $λ_{μ}$ the cosmological CP violation is generated at 1-loop level. With the purpose to relate the cosmological CP violation to the leptonic CP phase $δ$, we consider an extension of MSSM with two right handed neutrinos (RHN), which are degenerate in mass at high scales. Together with this, we first consider two texture zero $3\times 2$ Dirac Yukawa matrices of neutrinos. These via see-saw generated neutrino mass matrices augmented by single $ΔL=2$ dimension five ($\rm d=5$) operator give predictive neutrino sectors with calculable CP asymmetries. The latter is generated through $λ_{μ, τ}$ coupling(s) at 1-loop level. Detailed analysis of the leptogenesis is performed. We also revise some one texture zero Dirac Yukawa matrices, considered earlier, and show that addition of a single $ΔL=2$, $\rm d=5$ entry in the neutrino mass matrices, together with newly computed 1-loop corrections to the CP asymmetries, give nice accommodation of the neutrino sector and desirable amount of the baryon asymmetry via the resonant leptogenesis even for rather low RHN masses($\sim $few TeV -- $10^7$~GeV).

hep-ph↗

arXiv2017

Calculable Cosmological CP Violation and Resonant Leptogenesis

Within the extension of MSSM by two right handed neutrinos, which masses are degenerate at tree level, we address the issue of leptogenesis. Investigating the quantum corrections in details, we show that the lepton asymmetry is induced at 1-loop level and decisive role is played by the tau lepton Yukawa coupling. On a concrete and predictive neutrino model, which enables to predict the CP violating $δ$ phase and relate it to the cosmological CP asymmetry, we demonstrate that the needed amount of the baryon asymmetry is generated via the resonant leptogenesis.

hep-ph↗

arXiv2016

Soft See-Saw: Radiative Origin of Neutrino Masses in SUSY Theories

Radiative neutrino mass generation within supersymmetric (SUSY) construction is studied. The mechanism is considered where the lepton number violation is originating from the soft SUSY breaking terms. This requires MSSM extensions with states around the TeV scale. We present several explicit realizations based on extensions either by MSSM singlet or SU(2)_w triplet states. Besides some novelties of the proposed scenarios, various phenomenological implications are also discussed.

hep-ph↗

arXiv2016

Neutrino Mass Matrices from Two Zero 3x2 Yukawa Textures and Minimal d=5 Entries

Aiming to relate leptonic CP violating phase $δ$ to the cosmological CP asymmetry, we study the extension of MSSM by two quasi-degenerate (strictly degenerate at tree level) right-handed neutrinos and consider all possible two texture zero 3x2 Yukawa matrices plus one $ΔL=2$ dimension five (d=5) operator contributing to the light neutrino mass matrix. We classify all experimentally viable mass matrices, leading to several predictions, and analytically derive predictive relations. We also relate the CP violating $δ$ phase to the CP phase of the thermal leptogenesis.

hep-ph↗

arXiv2015

Natural Inflation from 5D SUGRA and Low Reheat Temperature

Motivated by recent cosmological observations of a possibly unsuppressed primordial tensor component $r$ of inflationary perturbations, we reanalyse in detail the 5D conformal SUGRA originated natural inflation model of Ref. [1]. The model is a supersymmetric variant of 5D extra natural inflation, also based on a shift symmetry, and leads to the potential of natural inflation. Coupling the bulk fields generating the inflaton potential via a gauge coupling to the inflaton with brane SM states we necessarily obtain a very slow gauge inflaton decay rate and a very low reheating temperature $T_r\stackrel{<}{_\sim }{\cal O}(100)$~GeV. Analysis of the required number of e-foldings (from the CMB observations) leads to values of $n_s$ in the lower range of present Planck 2015 results. Some related theoretical issues of the construction, along with phenomenological and cosmological implications, are also discussed.

hep-ph↗

arXiv2014

SU(5)xSU(5)' unification and D2 parity: Model for composite leptons

We study a grand unified SU(5)xSU(5)' model supplemented by D2 parity. The D2 greatly reduces the number of parameters and is important for phenomenology. The model, we present, has various novel and interesting properties. Because of the specific pattern of grand unification symmetry breaking and emerged strong dynamics at low energies, the Standard Model leptons, along with right-handed/sterile neutrinos, come out as composite states. The generation of the charged fermion and neutrino masses are studied within the considered scenario. Moreover, the issues of gauge coupling unification and nucleon stability are investigated in details. Various phenomenological implications are also discussed.

hep-ph↗

arXiv2013

Three Family SU(5) GUT and Inverted Neutrino Mass Hierarchy

Supersymmetric SU(5) GUT augmented with anomaly free U(1)_F flavor symmetry is presented. Very economical field content and U(1)_F charge assignment are obtained by specific construction. In particular, three families of 10+5* chiral matter, along the SU(5) singlet states (some of which serve as right handed neutrinos) are obtained. Appealing texture zero Yukawa matrices provide natural understanding of hierarchies between charged fermion masses and mixings. The model predicts inverted hierarchical neutrino mass scenario with interesting implications.

hep-ph↗

arXiv2011

New Flavor U(1)_F Symmetry for SUSY SU(5)

Within supersymmetric SU(5) Grand Unified Theory, we present several new scenarios with anomaly free flavor symmetry U(1)_F. Within each scenario, a variety of cases offer many possibilities for phenomenologically interesting model building. We present three concrete and economical models with anomaly free U(1)_F leading to natural understanding of observed hierarchies between charged fermion masses and CKM mixing angles.

hep-ph↗

arXiv2010

Constraining Proton Lifetime in SO(10) with Stabilized Doublet-Triplet Splitting

We present a class of realistic unified models based on supersymmetric SO(10) wherein issues related to natural doublet-triplet (DT) splitting are fully resolved. Using a minimal set of low dimensional Higgs fields which includes a single adjoint, we show that the Dimopoulos--Wilzcek mechanism for DT splitting can be made stable in the presence of all higher order operators without having pseudo-Goldstone bosons and flat directions. The μterm of order TeV is found to be naturally induced. A Z_2-assisted anomalous U(1)_A gauge symmetry plays a crucial role in achieving these results. The threshold corrections to alpha_3(M_Z), somewhat surprisingly, are found to be controlled by only a few effective parameters. This leads to a very predictive scenario for proton decay. As a novel feature, we find an interesting correlation between the d=6 (p\to e^+π^0) and d=5 (p\to ν-bar K+) decay amplitudes which allows us to derive a constrained upper limit on the inverse rate of the e^+π^0 mode. Our results show that both modes should be observed with an improvement in the current sensitivity by about a factor of five to ten.

hep-ph↗

arXiv2009

New Mechanism for Neutrino Mass Generation and Triply Charged Higgs Bosons at the LHC

We propose a new mechanism for generating small neutrino masses which predicts the relation m_ν~ v^4/M^3, where v is the electroweak scale, rather than the conventional seesaw formula m_ν~ v^2/M. Such a mass relation is obtained via effective dimension seven operators LLHH(H*H)/M^3, which arise when an isospin 3/2 Higgs multiplet Φis introduced along with iso-triplet leptons. The masses of these particles are naturally in the TeV scale. The neutral member of Φacquires an induced vacuum expectation value and generates neutrino masses, while its triply charged partner provides the smoking gun signal of this scenario. These triply charged bosons can be pair produced at the LHC and the Tevatron, with Φ^{+++} decaying into W^+l^+l^+ or W^+W^+W^+, possibly with displaced vertices. The leptonic decays of Φ^{+++} will help discriminate between normal and inverted hierarchies of neutrino masses. This scenario also allows for raising the standard Higgs boson mass to values in excess of 500 GeV.

hep-ph↗

arXiv2009

New Ways to Leptogenesis with Gauged B-L Symmetry

We show that in supersymmetric models with gauged B-L symmetry, there is a new source for cosmological lepton asymmetry. The Higgs bosons responsible for B-L gauge symmetry breaking decay dominantly into right-handed sneutrinos \tilde{N} and \tilde{N}* producing an asymmetry in \tilde{N} over \tilde{N}*. This can be fully converted into ordinary lepton asymmetry in the decays of \tilde{N}. In simple models with gauged B-L symmetry we show that resonant/soft leptogenesis is naturally realized. Supersymmetry guarantees quasi-degenerate scalar states, while soft breaking of SUSY provides the needed CP violation. Acceptable values of baryon asymmetry are obtained without causing serious problems with gravitino abundance.

hep-ph↗

arXiv2009

A New Extensions of MSSM: FMSSM

We propose an extension of the MSSM by adding vector like `matter' fields with masses near the TeV scale. This extension allows us to generate the masses of the bottom quark and tau lepton via radiative corrections such that only up type Higgs doublet couples with quarks and leptons. In addition to providing a natural explanation of the hierarchies between m_{b, τ} and m_t, this new extension, which we call FMSSM, allows the heavy sector of the MSSM Higgs bosons to be essentially fermiophobic as well as gaugephobic. Moreover, in this scenario there is no upper bound for the parameter \tan β. FMSSM can be distinguished from the MSSM, and has peculiar and unorthodox signals at the LHC, especially for the Higgs sector.

hep-ph↗