Zurab Tavartkiladze

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{sub {nu}}{approx}v{sup 4}/M{sup 3}, where v is the electroweak scale, rather than the conventional seesaw formula m{sub {nu}}{approx}v{sup 2}/M. Such a mass relation is obtained via effective dimension seven operators LLHH(H{sup {dagger}}H)/M{sup 3}, which arise when an isospin 3/2 Higgs multiplet {phi} is introduced along with isotriplet leptons. The masses of these particles are naturally in the TeV scale. The triply charged Higgs boson contained in {phi} can be pair produced at the LHC and the Tevatron, with {phi}{sup +++} decaying into W{sup +}l{sup +}l{sup +} or W{sup +}W{sup +}W{sup +}, possibly with displaced vertices. The leptonic decays of {phi}{sup +++} 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.

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 μ term of order TeV is found to be naturally induced. A Z2-assisted anomalous

Generation symmetry and E{sub 6} unification

mathcal{U}{(1)_A}

Predictive Model of Inverted Neutrino Mass Hierarchy and Resonant Leptogenesis

gauge symmetry plays a crucial role in achieving these results. The threshold corrections to α3(MZ), 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 → e+π0) and

Missing Partner Mechanism in SO(10) Grand Unification

d = 5left( {p to bar{nu }{K^{+} }} right)

Perturbativity and a fourth generation in the MSSM

decay amplitudes which allows us to derive a constrained upper limit on the inverse rate of the e+π0 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.

New Ways to Leptogenesis with Gauged B-L Symmetry

The group E{sub 6} for grand unification is combined with the generation symmetry group SO(3){sub g}. The coupling matrices in the Yukawa interaction are identified with the vacuum expectation values of scalar fields which are representations of the generation symmetry. These values determine the hierarchy of the fermions as well as their mixings and CP violation. This generation mixing appears in conjunction with the mixing of the standard model fermions with the heavy fermions present in the lowest representation of E{sub 6}. A close connection between charged and neutral fermions is observed relating for instance the Cabibbo-Kobayashi-Maskawa (CKM) mixings with the mass splittings of the light neutrinos. Numerical fits with only a few parameters reproduce quantitatively all known fermion properties. The model predicts an inverted neutrino hierarchy and gives rather strict values for the light and heavy neutrino masses as well as for the 0{nu}2{beta} decay parameter. It also predicts that the masses of the two lightest of six right handed neutrinos lie in the low TeV region.

A new extensions of MSSM: FMSSM

We present a new realization of inverted neutrino mass hierarchy based on flavor symmetry. In this scenario, the deviation of the solar oscillation angle from π/4 is correlated with the value of θ13, as they are both induced by a common mixing angle in the charged lepton sector. We find several interesting predictions: θ13 ≥ 0.13, sin2θ12 ≥ 0.31, sin2θ23 ≃ 0.5 and 0 ≤ cos δ ≤ 0.7 for the neutrino oscillation parameters and 0.01 ≲ mββ ≲ 0.02 eV for the effective neutrino mass in neutrino-less double β-decay. We show that our scenario can also explain naturally the observed baryon asymmetry of the universe via resonant leptogenesis. The masses of the decaying right-handed neutrinos can be in the range (103–107) GeV, which would avoid the generic gravitino problem of supersymmetric models.

New prediction for leptonic θ13

Abstract We present a new possibility for achieving doublet–triplet splitting naturally in supersymmetric SO ( 10 ) grand unified theories. It is based on a missing partner mechanism which is realized with the 126 + 126 ¯ Higgs superfields. These Higgs fields, which are also needed for generating Majorana right-handed neutrino masses, contain a pair of color triplets in excess of weak doublets. This feature enables us to remove the color triplets from the low energy spectrum without fine-tuning. We give all the needed ingredients for a successful implementation of the missing partner mechanism in SO ( 10 ) and present explicit models wherein the Higgs doublet mass is protected against possible non-renormalizable corrections to all orders. We also show how realistic fermion masses can be generated in this context.

Proton Stability In Supersymmetric SU(5)

Abstract We study an extension of the MSSM with a fourth generation of chiral matter. With this extension no value of tan β allows the theory to stay perturbative up to the GUT scale. We suggest one model with extra vector-like states at the TeV scale that allows perturbativity all the way up to the GUT scale.