Hiranmaya Mishra

Vacuum structure and chiral symmetry breaking in strong magnetic fields for hot and dense quark matter

We investigate chiral symmetry breaking in strong magnetic fields at finite temperature and densities in a 3 flavor Nambu Jona Lasinio (NJL) model including the Kobayashi Maskawa t-Hooft (KMT) determinant term, using an explicit structure for the ground state in terms of quark antiquark condensates. The mass gap equations are solved self consistently and are used to compute the thermodynamic potential. We also derive the equation of state for strange quark matter in the presence of strong magnetic fields which could be relevant for proto-neutron stars. ~

Thermal photons in QGP and non-ideal effects

We investigate the thermal photon production-rates using one dimensional boost-invariant second order relativistic hydrodynamics to find proper time evolution of the energy density and the temperature. The effect of bulk-viscosity and non-ideal equation of state are taken into account in a manner consistent with recent lattice QCD estimates. It is shown that the non-ideal gas equation of state i.e ε − 3 P ≠ 0 behaviour of the expanding plasma, which is important near the phase-transition point, can significantly slow down the hydrodynamic expansion and thereby increase the photon production-rates. Inclusion of the bulk viscosity may also have similar effect on the hydrodynamic evolution. However the effect of bulk viscosity is shown to be significantly lower than the non-ideal gas equation of state. We also analyze the interesting phenomenon of bulk viscosity induced cavitation making the hydrodynamical description invalid. It is shown that ignoring the cavitation phenomenon can lead to erroneous estimation of the photon flux.

Chiral symmetry breaking, color superconductivity and color neutral quark matter: a variational approach

Theory Division, Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, India(Dated: February 1, 2008)We investigate the vacuum realignment for chiral symmetry breaking and color superconductivityat finite density in Nambu-Jona-Lasinio model in a variational method. The treatment allows us toinvestigate simultaneous formation of condensates in quark antiquark as well as in diquark channels.The methodology involves an explicit construction of a variational ground state and minimisation ofthe thermodynamic potential. Color and electric charge neutrality conditions are imposed throughintroduction of appropriate chemical potentials. Color and flavor dependent condensate functionsare determined through minimisation of the thermodynamic potential. The equation of state iscalculated. Simultaneous existence of a mass gap and superconducting gap is seen in a smallwindow of quark chemical potential within the model when charge neutrality conditions are notimposed. Enforcing color and electric charge neutrality conditions gives rise to existence of gaplesssuperconducting modes depending upon the magnitude of the gap and the difference of the chemicalpotentials of the condensing quarks.

Leptogenesis with Heavy Majorana Neutrinos Revisited

The mass term for Majorana neutrinos explicitly violates lepton number. Several authors have used this fact to create a lepton asymmetry in the universe by considering CP violating eects in the one loop self-energy correction for the decaying heavy Majorana neutrino. We compare and comment on the dierent approaches used to calculate the lepton asymmetry including those using an eective Hamiltonian and resummed propagators. We also recalculate the asymmetry in the small mass dierence limit.

Dissipative properties of hot and dense hadronic matter in an excluded-volume hadron resonance gas model

We estimate dissipative properties viz: shear and bulk viscosities of hadronic matter using relativistic Boltzmann equation in relaxation time approximation within ambit of excluded volume hadron resonance gas (EHRG) model. We find that at zero baryon chemical potential the shear viscosity to entropy ratio (

Bulk and shear viscosities of hot and dense hadron gas

\eta/s

Medium modification of hadron masses and the thermodynamics of the hadron resonance gas model

) decreases with temperature while at finite baryon chemical potential this ratio shows same behavior as a function of temperature but reaches close to Kovtun-Son-Starinets (KSS) bound. Further along chemical freezout curve, ratio

Shear viscosity, cavitation and hydrodynamics at LHC

\eta/s

BCS-BEC crossover and phase structure of relativistic systems : A variational approach

is almost constant apart from small initial monotonic rise. This observation may have some relevance to the experimental finding that the differential elliptic flow of charged hadrons does not change considerably at lower center of mass energy. We further find that bulk viscosity to entropy density (

Color superconductivity and gapless modes in strange quark matter at finite temperatures

\zeta/s