Role of BCS-type pairing in light deformed nuclei: A relativistic mean field approach

We calculate the binding energy and deformation parameter for light nuclei with and without pairing using a deformed relativistic mean field model. The role of BCS-type pairing effect is analyzed for Ne and F isotopes. The calculated odd-even staggering and the deformation parameters argue strongly against the role of pairing in the light nuclei.Comment: 7 pages, 4 figure

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

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

Neutron star matter in an effective model

We study the equation of state (EOS) for dense matter in the core of the compact star with hyperons and calculate the star structure in an effective model in the mean field approach. With varying incompressibility and effective nucleon mass, we analyse the resulting EOS with hyperons in beta equilibrium and its underlying effect on the gross properties of the compact star sequences. The results obtained in our analysis are compared with predictions of other theoretical models and observations. The maximum mass of the compact star lies in the range $1.21-1.96 ~M_{\odot}$ for the different EOS obtained, in the model.Comment: 10 pages, 14 figures as appeared in PRC 74, 055803, (2006

Consistency of nuclear mass formulae

The general scepticism and loss of faith on the predictive ability of different mass formulae, arising out of the divergence of their predictions in unknown regions taken with respect to a reference mass formula, is successfully dispelled. When the result of relativistic mean field (RMF) theory with a Lagrangian common for all nuclei is taken as reference, the divergence disappears, and clear trend with strong correlation appears restoring our faith in general on the predictions of mass formulae, qualifying them as useful guideline for theoretical and experimental studies of nuclear phenomena.Comment: 6 pages, 4 figure

On the stability and the similarity of N=82 isotones

Here we study the stability and the similarity of all even $58\leq Z\leq 70, N=82 isotones. We confirm the two decades old study of one of the authors (AA) regarding the extra-ordinary stability and the similarity of these nuclei. We present here a new evidence which shows very strongly the said magicity of those nuclei and as such there exists a new ``plateau'' of magicity. Three well studied theoretical models which have been successfully applied in nuclear physics are used here to study the above phenomena. None of these model is able to reproduce the similarity and the doubly magic character of these nuclei. Therefore this hints at ``new physics'' in these N=82 isotones.Comment: 3 pages, 3 figures, Submitted for publicatio

Electrical Conductivity of an Anisotropic Quark Gluon Plasma : A Quasiparticle Approach

The study of transport coefficients of strongly interacting matter got impetus after the discovery of perfect fluid ever created at ultrarelativistic heavy ion collision experiments. In this article, we have calculated one such coefficient viz. electrical conductivity of the quark gluon plasma (QGP) phase which exhibits a momentum anisotropy. Relativistic Boltzmann's kinetic equation has been solved in the relaxation-time approximation to obtain the electrical conductivity. We have used the quasiparticle description to define the basic properties of QGP. We have compared our model results with the corresponding results obtained in different lattice as well as other model calculations. Furthermore, we extend our model to calculate the electrical conductivity at finite chemical potential.Comment: 8 pages, 4 figure

Baryon Number Penetrability as a Measure of Isothermal Baryon Number Fluctuations in the Early Universe

We have examined the efficiency of baryon-number transport mechanism across the phase boundary in a cosmological quark-hadron phase transition through the proper estimate of baryon-number penetrability . For this purpose we have derived first the double-pair creation probability $P_b$ in terms of single-pair creation probabilty per unit time and unit volume $\kappa_m$ and then obtained an analytical expression for . Our calculation is free from the uncertainty of the value of double-pair creation probability per unit time and unit volume $\kappa_b$ which was used as a free parameter in earlier calculations. Finally the variations of double-pair creation probability $P_b$ as well as $$ with temperature are shown and compared with other known results.Comment: 18 pages LaTeX including five figures in eps forma

1/f noise and multifractality in atmospheric-CO2 records

We study the fluctuations in the measured atmospheric CO2 records from several stations and show that it displays 1/f noise and multifractality. Using detrended fluctuation analysis and wavelet based methods, we estimate thescaling exponents at various time scales. We also simulate CO2 time series from an atmospheric chemistry-transport model (CTM) and show that eventhough the model results are in broad agreement with the measured exponents there are still some discrepancies between them. The implications for sources and sinks inversion of atmospheric-CO2 is discussed.Comment: 5 pages, 4 figure