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  • Extra Dimensions: From 1998, there has been a resurgence of interest in Kaluza Klein theories due to brane-world models. From the very beginning, I have been engaged in the study of these models and their consequences for high-energy experiments like the Tevatron and the LHC. Some of the first papers to study the model of Large Extra Dimensions proposing signatures to test this model were written by me and my collaborators, Sreerup Raychaudhuri and Prakash Mathews. Over the years, I have studied other models of extra dimensions like the Randall-Sundrum Model. In recent years, the focus of my research has been on realistic models of extra-dimensions and I am studying the signatures, at leading and next-to-leading order in QCD, from the point of view of the theory's testability.
  • Supersymmetry: In supersymmetry, I have largely focussed on the study of R-parity violating models. In early papers with Gautam Bhattacharyya, Debajyoti Choudhury and John Ellis, I studied the constraints on these models arising from electroweak precision tests. With Magda Lola and John Ellis, I later made a critical study of R-parity violating explanations of the anomalous events seen at HERA. Later, with Ben Allanach I studied an excess of muon+photon+missing transverse energy events reported by the CDF experiment and attempted to explain this in terms of a R-parity violating model of gauge mediated supersymmetry breaking.
  • QCD: I have worked extensively in Non-Relativistic QCD (NRQCD) and its applications to the study of quarkonium production. My paper with D.P. Roy was one of the earliest to uncover a fragmentation contribution in J/psi production at the Tevatron. This model succesfully explained the huge anomalous contribution in J/psi production reported by the CDF experiment. I also studied other final states like psi(prime) and J/psi+photon. With Alan Martin and James Stirling, I made a systematic study of J/psi production of Tevatron and HERA and attempted to explain the combined data in NRQCD. Using NRQCD, I made a prediction for the 1P1 charmonium state (h_c) at the Tevatron and in a recent paper I have extended this analysis to the LHC. Earlier, I had studied polarised structure functions and the proton spin problem and also the effects of a nuclear environment on structure functions. My QCD interests have resurfaced in recent years in the guise of next-to- leading order corrections to new physics processes that I have computed.
  • GUTs: In my early years, I had worked on models of grand unification and tried to obtain constraints on GUT models from the precise measurements of couplings made at the Large Electron-Positron Collider. I also attempted to study non-standard models like non-perturbative unification scenarios in this context.
  • Higgs: With Fawzi Boudjema and Genevieve Belanger, I studied an interesting model of supersymmetry with a very light stop. The stop contributions to Higgs production at the LHC were shown to cancel the top contributions so that the standard Higgs production via top loops does not provide a viable signal at the LHC. Alternative production mechanisms like the associated production of Higgs with a tt(bar) pair were studied and the viability of the signals were critically analysed. I had earlier studied invisible Higgs decays in the context of the singlet Majoron model and had shown how, in spite of the invisible decay channels of the Higgs in this model, the data from LEP could be used to constrain the Higgs mass in this model.