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A. Kobakhidze

Publications and source records attributed to A. Kobakhidze.

7 recordsLinked to original sources
arXiv2007

A simple explanation of the PVLAS anomaly in spontaneously broken mirror models

The PVLAS anomaly can be explained if there exist millicharged particles of mass $\stackrel{<}{\sim} 0.1$ eV and electric charge $ε\sim 10^{-6} e$. We point out that such particles occur naturally in spontaneously broken mirror models. We argue that this interpretation of the PVLAS anomaly is not in conflict with astrophysical constraints due to the self interactions of the millicharged particles which lead them to be trapped within stars. This conclusion also holds for a generic paraphoton model.

hep-ph↗
arXiv2001

Composite quarks and leptons in higher space-time dimensions

A new approach towards the composite structure of quarks and leptons in the context of the higher dimensional unified theories is proposed. Owing to the certain strong dynamics, much like an ordinary QCD, every possible vectorlike multiplets of composites appear in higher dimensional bulk space-time, however, through a proper Sherk-Schwarz compactification only chiral set of composite quarks and leptons survive as the massless states in four dimensions. In this scenario restrictions related with the 't Hooft's anomaly matching condition are turned out to be avoided and, as a result, the composite models look rather simple and economic. We demonstrate our approach by an explicit construction of model of preons and their composites unified in the supersymmetric SU(5) GUT in five space-time dimensions. The model predicts exactly three families of the composite quarks and leptons being the triplets of the chiral horizontal symmetry SU(3)_h which automatically appears in the composite spectrum when going to ordinary four dimensions.

hep-ph↗
arXiv2001

Radions in a $γγ$ collider

We study the resonance production of radions via $γγ$ fusion in the Randall-Sundrum model. We find that the cross section of the process in the $γγ$ mode of a linear collider (LC) can be of similar size as in the $e^+e^-$ collision mode, if the radion is heavy. We consider the possible curvature-Higgs mixing in the model, and we find that the mixing should be constrained in order to avoid an unphysical state. The process $γγ\to ϕ$ is the main source of radions at LC near the conformal limit. We consider both the decay modes of radion with curvature-Higgs mixing and without. Our results show that the radion with mass below 800 GeV could be detected at LC with any mixing parameter and vacuum expectation value of the radion around 1 TeV.

hep-ph↗
arXiv1996

Natural suppression of d=5 operator induced proton decay in supersymmetric grand unified theories

The proton decay in supersymmetric (SUSY) Grand Unified Theories (GUTs), where the special mechanism provides the natural suppression of the dimension 5 ($d=5$) operators, was studied. Due to this mechanism, $d=5$ operator induced proton decay takes place only through the mixing of light generation fermions with those from third generation and crucially depends on the structure of fermion mass matrices. We show that in general proton decay is strongly suppressed relative to the standard SUSY GUT situation and for wide class of fermion mass matrices the SUSY parameter space practically has no restrictions.

hep-ph↗
arXiv1996

On the possible solution of the doublet-triplet problem in extended $SU(\geq 8)$ SUSY GUTs

The generalization of the "custodial symmetry" mechanism which leads to the natural (without fine tuning) explanation of the doublet-triplet hierarchy is suggested in the frames of extended $SU(N\geq 8)$ SUSY GUTs. It is shown also that such type of SUSY GUT can predict the value of strong gauge coupling constant $α_S(M_Z)$ consistent with present experimental data.

hep-ph↗
arXiv1995

Missing Doublet Multiplet as the Origin of the Doublet-Triplet Splitting in SUSY SU(6)

In a $SU(6)$ gauge theory we found the irreducible representation (175-plet) which does not contain the Higgs doublet. Using this representation we construct two SUSY $SU(6)$ models in which the doublet-triplet splitting occurs naturally, without fine tuning. The crucial role is played by the ``custodial" global $SU(2)_H$ in combination with discrete or continuous $R$ symmetries.

hep-ph↗