A Lepton-specific Universal Seesaw Model with Left-Right Symmetry

We propose a left-right symmetric framework with universal seesaw mechanism for the generation of masses of the Standard Model quarks and leptons. Heavy vector-like singlet quarks and leptons are required for generation of Standard Model-like quark and lepton masses through seesaw mechanism. A softly broken $Z_2$ symmetry distinguishes the lepton sector and the quark sector of the model. This leads to the presence of some lepton-specific interactions that can produce unique collider signatures which can be explored at the current Large Hadron Collider run and also future colliders.Comment: 15 Pages, 3 figure

Distinguishing split supersymmetry in Higgs signals at the Large Hadron Collider

We examine the possibility of detecting signals of split supersymmetry in the loop-induced decay h --> gamma gamma of the Higgs boson at the Large Hadron Collider, where charginos, as surviving light fermions of the supersymmetric spectrum, can contribute in the loop. We perform a detailed study of uncertainties in various parameters involved in the analysis, and thus the net uncertainty in the standard model prediction of the rate. After a thorough scan of the parameter space, taking all constraints into account, we conclude that it will be very difficult to infer about split supersymmetry from Higgs signals alone.Comment: 22 pages, 14eps figures, LateX, Changes in the figures and minor modifications in the text. Final version to appear in Physical Review

Right-chiral sneutrinos and long-lived staus: event characteristics at the Large Hadron Collider

We investigate the signals of a supersymmetric scenario where the lighter tau-sneutrino is the lightest supersymmetric particle, while the lighter stau-state is the next lightest. We confirm that such a scenario can be motivated within the framework of minimal supergravity, with just the addition of a right-chiral neutrino superfield. Such a spectrum leads to rather unusual signals of supersymmetry, showing stable tracks of the stau in the muon chambers. We have studied two types of signals, namely, (a) two or more hard jets and two stau tracks, and (b) hard jets with two muons and two stau tracks. We demonstrate that the stau tracks can be distinguished from the muonic ones through proper kinematic cuts which also enable one to remove all standard model backgrounds.Comment: Latex2E, 18 pages, 8 eps figures included (To appear in Phys.Rev. D