Sreerup Raychaudhuri

How Constrained is the cMSSM

We study the allowed parameter space of the constrained minimal supersymmetric Standard Model (cMSSM) in the light of direct searches, constraints from B-physics (including the recent measurement of the branching ratio for Bs → � + � ) and the dark matter relic density. For low or moderate values of tanβ, the strongest constraints are those imposed by direct searches, and therefore, large areas of the parameter space are still allowed. In the large tanβ limit, however, the B-physics constraints are more restrictive, effectively forcing the squark and gluino masses to lie close to or above a TeV. A light Higgs boson could dramatically change the allowed parameter space, but we need to know its mass precisely for this to be effective. We emphasize that it is still too early to write off the cMSSM, even in the large tanβ limit. Finally we explore strategies to extend the LHC search for cMSSM signals beyond the present reach of the ATLAS and CMS Collaborations.

Getting to the top with extra dimensions

Abstract The prospect of large extra dimensions and an effective theory of gravity at around a TeV has interesting experimental consequences. In these models, the Kaluza–Klein modes interact with Standard Model particles and these interactions lead to testable predictions at present and planned colliders. We investigate the effect of virtual exchanges of the spin-2 Kaluza–Klein modes in the production cross-section of t t pairs at the Tevatron and the LHC and find that the t t cross-section can be an effective probe of the large extra dimensions. This enables us to put bounds on the effective low-energy scale.

Sharpening up the charged Higgs boson signature using tau polarization at the CERN LHC.

The opposite states of the {tau} polarization resulting from the charged Higgs boson and the {ital W} boson decays can be exploited to enhance the {ital H}{sup {plus_minus}} signal in the inclusive one-prong hadronic decay channel of {tau}. We suggest practical methods of sharpening up the {ital H}{sup {plus_minus}} signature in the top quark decay at the CERN LHC using this idea. As a result one can carry on the charged Higgs boson search to within {approximately}20 GeV of the parent top quark mass over the full parameter space of the MSSM. {copyright} {ital 1996 The American Physical Society.}

Vacuum stability constraints and LHC searches for a model with a universal extra dimension

If the new boson lying in the narrow mass range between 122 and 127 GeV is confirmed to be a Higgs boson, then stability of the electroweak vacuum in a minimal model with a universal extra dimension (mUED) will require a much lower cutoff for the theory than has been envisaged earlier. We show that this low cutoff leads to important changes in much of the minimal model with a universal extra dimension phenomenology studied till now. In particular, prospects for LHC searches for

Charged Higgs boson search at the Fermilab Tevatron upgrade using tau polarization.

n=1

R-parity violation at HERA?

states are rather limited, while resonant

Do new data on [B+ -> tau+ nu_tau] decays point to an early discovery of supersymmetry at the LHC?

n=2

Testing TeV scale quantum gravity using Dijet production at the Tevatron

states may go completely undetected. Prospects for detection at high energy

Observing virtual light supersymmetric particles at LEP-II

{e}^{+}{e}^{\ensuremath{-}}

Azimuthal Angle Probe of Anomalous HWW Couplings at a High Energy ep Collider

colliders are less affected.