Search

Investigations of the phase diagram of quantum chromodynamics (QCD) have revealed that exotic new phases, the so called {\it color superconducting phases}, may arise at very high baryon densities. It is speculated that these exotic phases may arise in the cores of neutron stars. Focus on neutrons stars has tremendously intensified in recent years with the direct detection of gravitational waves (GW) by LIGO/Virgo from BNS merger events which has allowed the possibility of directly probing the properties of the interior of a neutron star. A remarkable phenomenon manifested by rapidly rotating neutron stars is in their {\it avatar} as {\it Pulsars}. The accuracy of pulsar timing can reach the level of one part in 10$^{15}$, comparable to that of atomic clocks. This suggests that even a tiny deformation of the pulsar can leave its imprints on the pulses by inducing tiny perturbations in the entire moment of inertia (MI) tensor affecting the pulse timings, as well as the pulse profile (from wobbling induced by off-diagonal MI components). This may allow a new probe of various phase transitions occurring inside a pulsar core through induced density fluctuations affecting the MI tensor. Such perturbations also naturally induce a rapidly changing quadrupole moment of the star, thereby providing a new source of gravitational wave emission. Another remarkable possibility arises when we consider the effect of an external GW on neutron star. With the possibility of detecting any minute changes in its configuration through pulse observations, the neutron star has the potential of performing as a Weber detector of gravitational wave. This brief review will focus on these specific aspects of a pulsar. Specifically, the focus will be on the type of physics which can be probed by utilizing the effect of changes in the MI tensor of the pulsar on pulse properties., Review article, 27 pages, 10 figures, comments are welcome

Flat directions in supersymmetric models can get large vacuum expectation values in the early Universe which leads to a large mass for gauge bosons and gauginos. We point out that this can then result in enhanced gravitino production because the cross-section for the production of the +/- 1/2 helicity states of the gravitino is proportional to the square of the gaugino masses. We consider gravitino production after inflation in such a scenario and find that the abundance in some cases can be much larger than the upper bound on the gravtino abundance from cosmological constraints unless the flat direction field has a very small vacuum expectation value when it commences oscillating., Comment: 5 pages

In this paper, we explore the possibility of spontaneous CP violation in the scattering of quarks and anti-quarks from QCD Z(3) domain walls. The CP violation here arises from the nontrivial profile of the background gauge field $(A_{0})$ between different Z(3) vacua. We calculate the spatial variation of $A_{0}$ across the Z(3) interface from the profile of the Polyakov loop $L(\vec{x})$ for the Z(3) interface and calculate the reflection of quarks and antiquarks using the Dirac equation. This spontaneous CP violation has interesting consequences for the relativistic heavy-ion collision experiments, such as baryon enhancement at high $P_{T}$. It also acts as a source of additional J/$\psi$ suppression. We also discuss its implications for the early universe., Comment: 13 pages, Latex, 7 figures, Two different effective potentials studied with similar temperatures showing consistent results. Final published version

We consider salient cosmological features of a supersymmetric model which is Left-Right symmetric and therefore possessing gauged $B-L$ symmetry. The requirement of breaking parity and also obtaining charge preserving vacua introduces some unique features to this model (MSLRM), resulting in a preference for non-thermal Leptogenesis. Assuming that the model preserves TeV scale supersymmetry, we show that the vacuum structure generically possesses domain walls, which can serve two important purposes. They can signal a secondary inflation required to remove unwanted relics such as gravitino and moduli and also generate lepton asymmetry by a mechanism similar to electroweak baryogenesis. The requirement of disappearance of domain walls imposes constraints on the soft parameters of the theory, testable at the TeV scale. We also propose an alternative model with spontaneous parity violation (MSLR\rlap/P). Incorporating the same cosmological considerations in this case entails constraints on a different set of soft parameters., 18 pages. Minor changes in text, but conclusion remains same. Published in Phys. Rev. D