Singularity: Raychaudhuri Equation once again

I first recount Raychaudhuri's deep involvement with the singularity problem in general relativity. I then argue that precisely the same situation has arisen today in loop quantum cosmology as obtained when Raychaudhuri discovered his celebrated equation. We thus need a new analogue of the Raychaudhuri equation in quantum gravity.Comment: 11 pages, Contribution to Special issue of Pramana on Raychaudhuri Equation at Cross-roads, edited by Naresh Dadhich, Pankaj Joshi and Probir Ro

Signals for R-parity-violating Supersymmetry at a 500 GeV e+ e- Collider

We investigate the production of charginos and neutralinos at a 500 GeV e^+e^- collider (NLC) and study their decays to the lightest neutralino, which then decays into multi-fermion final states through couplings which do not conserve R-parity. These couplings are assumed to affect only the decay of the lightest neutralino. Detailed analyses of the possible signals and backgrounds are performed for five selected points in the parameter space.Comment: 42 pages, LaTeX, 12 postscript figure

On a Raychaudhuri equation for hot gravitating fluids

We generalize the Raychaudhuri equation for the evolution of a self gravitating fluid to include an Abelian and non-Abelian hybrid magneto fluid at a finite temperature. The aim is to utilize this equation for investigating the dynamics of astrophysical high temperature Abelian and non-Abelian plasmas.Comment: 13 pages, Invited contribution to Pramana special issue dedicated to A.K. Raychaudhuri, "The Raychaudhuri equation and its role in Modern Cosmology". Pramana style files include

Testing Times for Supersymmetry: Looking Under the Lamp Post

We make a critical study of two highly-constrained models of supersymmetry --- the constrained minimal supersymmetric standard model (cMSSM), and the non-universal Higgs mass model (NUHM) --- in the light of the 125-126 GeV Higgs boson, the first observation of $B_s \to \mu\mu$ at the LHCb, and the updated $B \to \tau \nu$ branching ratio at BELLE. It turns out that these models are still allowed by the experimental data, even if we demand that there be a light stop with mass less than 1.5 TeV. The only significant effects of all these constraints are to push the mass of the light stop above $\sim 500$ GeV, and to prefer the universal trilinear coupling $A_0$ to be large and negative. We calculate the Higgs boson branching ratios to $WW, ZZ, \tau\tau$ and $\gamma\gamma$ in these models and show that improved experimental limits on these could put them to the most stringent experimental tests yet.Comment: Updated version consistent with recent data, a few references adde