arXiv subjects
Publications and source records attributed to Avtar Singh Sehra.
The photon vacuum polarization effect in curved spacetime leads to birefringence, i.e. the photon velocity becomes greater than (or less than) the speed of light depending on its polarization. We investigate this phenomenon in a Schwarzschild curved spacetime.
In part I we study quantum modified photon trajectories in a Schwarzschild blackhole spacetime. The photon vacuum polarization effect in curved spacetime leads to birefringence, i.e. the photon velocity becomes c+/-dc depending on its polarization. This velocity shift then results in modified photon trajectories. In this work we give an introduction to this quantum effect in relativity and we study its effects in Schwarzschild spacetime for critical orbits. Some key results are that the critical orbits are shifted depending on polarization and the event horizon remains fixed. In Part II we use the 2+1d Nambu-Jona-Lasino NJL model to study the superfluid behaviour of two-dimensional quark matter. We begin with an introduction to QCD its symmetries and the NJL model. We then go on to study the 2+1d NJL model. We show that at high density the 2+1d NJL model represents a relativistic gapless thin film BCS superfluid.
We present results of numerical simulations of the 2+1d Nambu -- Jona-Lasinio model with non-zero baryon chemical potential mu and spatially-varying complex diquark source strength j. By choosing arg(j) to vary smoothly through 2 pi across the spatial extent of the lattice, a baryon number current is induced which in the high density phase remains non-vanishing as |j|->0; we are hence able to extract a quantity characteristic of a superfluid known as the helicity modulus. We also study supercurrent flow at non-zero temperature and estimate the critical temperature at which the normal phase is restored, which is consistent with the conventional picture for thin-film superfluids in which the transition is viewed in terms of vortex -- anti-vortex unbinding.