Quenching of Hadron Spectra in a chemically equilibrating Quark-Gluon Plasma

Using the Fokker-Planck equation we have studied the drag co-efficient $A(t)$ and the consequent shift $\Delta p_\perp (L)$ in the transverse momentum due to collisional energy loss of energetic partons while passing through a chemically equilibrating quark-gluon plasma. Based on these we estimate the quenching factor $Q(p_\perp)$ when the medium is undergoing longitudinal expansion governed by master rate equations. In contrast to the case of chemically equilibrated plasma investigated earlier by Mustafa and Thoma \cite{mus} we find less quenching because our calculated $Q(p_\perp)$ is always greater at all momenta. This result is attributed to the weak drag coefficient operating during initial state interactions.Comment: 12 pages, 3 figure

On the Non-Orthonormality of Lippmann-Schwinger-Low States

It is pointed out that for a general short-ranged potential the Lippmann-Schwinger-Low scattering state $|\psi^L_k>$ does not strictly satisfy the Schrodinger eigen equation, and the pair $|\psi^L_n>$, $|\psi^L_k>$ is mutually nonorthogonal if $E_n=E_k$. For this purpose, we carefully use an infinitesimal adiabatic parameter $\epsilon$, a nonlinear relation among transition amplitudes, and a separable interaction as illustration.Comment: 9 pages (modified version

Comment on Chernavskaya's Paper ``Double Phase Transition Model and the Problem of Entropy and Baryon Number Conservation" hep-ph/9701265

We comment on the paper hep-ph/9701265.Comment: 4 pages LaTe

New relativistic effective interaction for finite nuclei, infinite nuclear matter and neutron stars

We carry out the study for finite nuclei, infinite nuclear matter and neutron star properties with the newly developed relativistic force named as the Institute Of Physics Bhubaneswar-I(IOPB-I). Using this force, we calculate the binding energies, charge radii and neutron skin thickness for some selected nuclei. From the ground state properties of superheavy element i.e. Z=120, it is noticed that considerable shell gaps appear at neutron numbers N=172, 184 and 198, showing the magicity of these numbers. The low density behavior of the equation of state for pure neutron matter is compatible with other microscopic models. Along with the nuclear symmetry energy, its slope and curvature parameters at the saturation density are consistent with those extracted from various experimental data. We calculate the neutron star properties with the equation of state composed of nucleons and leptons in $\it beta-equilibrium$ which are in good agreement with the X-ray observations by Steiner and N\"{a}ttil\"{a}. We find that the maximum mass of the neutron star to be 2.15$M_{\odot}$ and stellar radius 11.936 km . Moreover, the radius and tidal deformability of a {\it canonical} neutron star mass 1.4$M_\odot$ come out to be 13.242 km and 3.910$\times$10$^{36}$ g cm$^2$ s$^2$ respectively within this parameter set.Comment: 17 pages, 9 figures and comments are welcom

Effective relativistic mean field model for finite nuclei and neutron stars

New Relativistic mean field parameter set IOPB-I has been developed

Phase transition and properties of compact star

We investigate the phase transition to a deconfined phase and the consequences in the formation of neutron stars. We use the recently proposed effective field theory motivated relativistic mean field theory for hadron and the MIT Bag model and color-flavor locked (CFL) phase for the quark matter in order to get the appropriate equation of state. The properties of star are then calculated. The differences between unpaired and CFL quark matter are discussed.Comment: 11 pages with 7 figure

Large Strangeness as a QGP Signal in an Isentropic Quark-Hadron Phase Transition

Lattice QCD results reveal that the critical parameters and the order of the quark-hadron phase transition are quite sensitive to the number of dynamical flavours and their masses included in the theory. Motivated by this result we develop a phenomenological equation of state for the quark-gluon plasma consisting of $n_f$ flavours retaining the entropy per baryon ratio continuous across the quark-hadron phase boundary. We thus obtain a generalised expression for the temperature and baryon chemical potential dependent bag constant. The results are shown for the realistic case, i.e., involving u, d and s quarks only. We then obtain a phase boundary for an isentropic quark-hadron phase transition using Gibbs' criteria. Similarly another phase boundary is obtained for the transition to an ideal QGP from the solution of the condition $B(\mu,T)=0$. The variation of critical temperature $T_c$ with the number of flavours included in the theory. Also the variation of ${(\epsilon-4P)}/T^4$ with temperature are studied and compared with lattice results. Finally the strange particle ratios $\frac{\bar{\Lambda}}{\Lambda}$, $\frac{\bar{\Xi}}{\Xi}$ and $\frac{K^+}{K^-}$ are obtained at both phase boundaries. We propose that their variations with the temperature and baryon chemical potential can be used in identifying the quark-gluon plasma in the recent as well as in future heavy-ion experiments.Comment: 16 pages Latex File, 5 figures available on reques

Dissociation of 1 p quarkonium states in a hot QCD medium

We extend the analysis of a very recent work (Phys. Rev. {\bf C 80}, 025210 (2009)) to study the dissociation phenomenon of 1p states of the charmonium and bottomonium spectra ($\chi_c$ and $\chi_b$) in a hot QCD medium. This study employed a medium modified heavy quark potential which is obtained by incorporating both perturbative and non-perturbative medium effects encoded in the dielectric function to the full Cornell potential. The medium modified potential has a quite different form (a long range Coulomb tail in addition to the usual Yukawa term) compared to the usual picture of Debye screening. We further study the flavor dependence of their binding energies and dissociation temperatures by employing the perturbative, non-perturbative, and the lattice parametrized form of the Debye masses. These results are consistent with the predictions of the current theoretical works.Comment: 7 pages, 2 figures, 3 tables, two colum

New parameterization of the effective field theory motivated relativistic mean field model

A new parameter set is generated for finite and infinite nuclear system within the effective field theory motivated relativistic mean field (ERMF) formalism. The isovector part of the ERMF model employed in the present study includes the coupling of nucleons to the {\delta} and \r{ho} mesons and the cross-coupling of \r{ho} mesons to the {\sigma} and {\omega} mesons. The results for the finite and infinite nuclear systems obtained using our parameter set are in harmony with the available experimental data. We find the maximum mass of the neutron star to be 2.03M\odot? and yet a relatively smaller radius at the canonical mass, 12.69 km, as required by the available data.Comment: 5 pages, 4 figures, Accepted Nucl. Phys.

Effective field theory: A complete relativistic nuclear model

We analyzed the results for finite nuclei and infinite nuclear and neutron matter using the standard $\sigma-\omega$ model and with the effective field theory. For the first time, we have shown here quantitatively that the inclusion of self-interaction of the vector mesons and the cross-interaction of all the mesons taken in the theory explain naturally the experimentally observed softness of equation of state without loosing the advantages of standard $\sigma-\omega$ model for finite nuclei. Recent experimental observations support our findings and allow us to conclude that without self- and cross-interactions the relativistic mean field theory is incomplete.Comment: 4 pages, 4 figure