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Strom A.,Gothenburg University | Johannesson H.,Gothenburg University | Japaridze G.I.,Andronikashvili Institute of Physics | Japaridze G.I.,Ilia State University
Physical Review Letters | Year: 2010

We analyze the dynamics of the helical edge modes of a quantum spin Hall state in the presence of a spatially nonuniform Rashba spin-orbit (SO) interaction. A randomly fluctuating Rashba SO coupling is found to open a scattering channel which causes localization of the edge modes for a weakly screened electron-electron (e-e) interaction. A periodic modulation of the SO coupling, with a wave number commensurate with the Fermi momentum, makes the edge insulating already at intermediate strengths of the e-e interaction. We discuss implications for experiments on edge state transport in a HgTe quantum well. © 2010 The American Physical Society.

Gogoladze I.,University of Delaware | Gogoladze I.,Andronikashvili Institute of Physics | Nasir F.,University of Delaware | Shafi Q.,University of Delaware
International Journal of Modern Physics A | Year: 2013

We demonstrate that natural supersymmetry is readily realized in the framework of SU(4)c ×SU(2)L ×SU(2)R with nonuniversal gaugino masses. Focusing on ameliorating the little hierarchy problem, we explore the parameter space of this model which yields small fine-tuning measuring parameters (natural supersymmetry) at the electroweak scale (ΔEW) as well as at high scale (ΔHS). It is possible to have both ΔEW and ΔHS less than 100 in these models, (2% or better fine-tuning), while keeping the light CP-even (Standard Model-like) Higgs mass in the 123-127 GeV range. The light stop quark mass lies in the range 700 GeV < mt̄1 < 1500 GeV, and the range for the light stau lepton mass is 900 GeV m t̄1 < 1300 GeV. The first two family squarks are in the mass range 3000 GeV < mt̄1 < 4500 GeV, and for the gluino we find 2500 GeV < mt̄1 < 3500 GeV. We do not find any solution with natural supersymmetry which yields significant enhancement for Higgs production and decay in the diphoton channel. © 2013 World Scientific Publishing Company.

Tavartkiladze Z.,Andronikashvili Institute of Physics | Tavartkiladze Z.,Ilia State University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

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. © 2011 Elsevier B.V.

Gogberashvili M.,Andronikashvili Institute of Physics | Gogberashvili M.,Tbilisi State University | Midodashvili P.,Ilia State University | Midodashvili L.,Gori University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

We investigate the problem of localization of gauge fields within the 5D standing wave braneworld model and show that in the case of increasing warp factor there exist normalizable vector field zero modes on the brane. © 2011 Elsevier B.V.

Tskhakaya D.,University of Innsbruck | Tskhakaya D.,Andronikashvili Institute of Physics
Contributions to Plasma Physics | Year: 2012

Recent results of massively parallel kinetic (PIC/MC) simulations of the tokamak scrape-off layer are discussed. It is demonstrated that a number of well studied properties of the low-recycling divertor plasma, such as the sound speed and the average energy of plasma particles impinging on the divertors, cannot be generalized to the high recycling case. A new analytical model for plasma boundary condition has been derived. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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