118554608
Isospin asymmetric nuclear matter and properties of axisymmetric neutron stars
The theoretical study of the nuclear equation of state is a field of research which ties together different areas of physics. Nuclear EoS is of great interest as its features control the stability of neutron star (NS), the evolution of the universe, supernova explosion, nucleosynthesis as well as central collisions of heavy nuclei. Extensive studies in the past two decades of nuclear matter created at subnormal or supernormal density in heavy ion collisions have resulted in experimental constraints on the nuclear EoS of symmetric matter. Recent astrophysical observations of massive neutron stars and heavy-ion data are confronted with our present understanding of the EoS of dense hadronic matter. We argue that the data from massive neutron stars and pulsars provide an important cross-check between high-density astrophysics and heavy-ion physics. The density dependence of nuclear symmetry energy (NSE) obtained by using nuclear EoS plays an important role for modelling the structure of the neutron stars (NSs) and the dynamics of supernova explosions since a series of observables (e.g. slope L of NSE, the value of NSE at nuclear density etc.) can be determined from the knowledge of symmetry energy. The stiffness of the high-density matter controls the maximum mass of compact stars. New measurements of the properties of pulsars point towards large masses and correspondingly to a rather stiff EoS [1] characterized by symmetric nuclear matter (SNM) incompressibility 250270 MeV or more. In a recent analysis of x-ray burster EXO 0748-676 (M= 2:10 � 0:28 M� ) it is even claimed that soft nuclear EoS are ruled out [2]. In addition, it is argued in Ref.[2] that condensates and deconfined quarks [3] may not exist in the cores of NSs. Recently, new observations for the mass and the radius of compact stars have been obtained which provide stringent constraints on the EoS of strongly interacting matter at high densities [4, 5].
18828906
Temperature Dependence of Hadron Masses from the Zimanyi-Moszkowski Model
An extended version of the Zimanyi-Moskowski (ZM) model has been used to calculate the temperature dependence of the hadronic masses. The calculation of meson masses in the Random Phase Approximation (RPA) gives an increase in the $\sigma$, $\omega$ and $\pi$ effective masses with temperature.
3112149
Pion Dissociation In Hot Quark Medium
Pion dissociation in a medium of hot quark matter is studied. The decay width of pion is found to be large but finite at temperatures much higher than the so called critical temperature of chiral or deconfinement transition. Consequently, pions should coexist with quarks and gluons at such high temperatures. The result is in agreement with the lattice calculations. The implication of the above result in the study of Quark-Gluon plasma is discussed.
119328473
QCD phase transition in rotating neutron star, neutrino beaming and gamma-ray bursters
We have studied the emission of neutrinos from a rotating hybrid star. We find that the emission is predominantly confined to a very small angle, provided the core of the star is in a mixed phase of quarks and hadrons and the size of such a mixed phase is small. Annihilation of neutrinos to produce gamma rays has been discussed. The estimated duration of the burst is found to be within the observational range.
117589122
In-medium effects on the {phi} meson
The temperature dependence of the {phi} meson mass and its decay width ({phi}{r_arrow}K{bar K}) have been studied from an effective nonlinear chiral Lagrangian in SU(3). The effective mass has been obtained from the pole position of the full propagator. The width has also been calculated. It has been found that the mass decreases with temperature very slowly whereas the decay width increases quite sharply. Possible consequences on the QGP signals are discussed. {copyright} {ital 1997} {ital The American Physical Society}
118314565
Stability against {alpha} decay of some recently observed superheavy elements
The probability of {alpha}-particle emission for some recently observed superheavy nuclei (SHN) are investigated. The {alpha}-decay half-lives of SHN are calculated in a quantum tunneling model with density-dependent M3Y (DDM3Y) effective nuclear interaction using theoretical and measured Q{sub {alpha}} values. We determine the density distribution of {alpha} and daughter nuclei from the relativistic mean-field (RMF) theory using FSUGold force, NL3, and TM1 parameter sets. The double-folded nuclear potential is numerically calculated in a more microscopic manner using these density distributions. The estimated values of {alpha}-decay half-lives are in good agreement with the recent data. We compare our results with recently detected {alpha}-decay chains from a new element with atomic number Z=117 reported by the Joint Institute for Nuclear Research, Dubna. Finally, we determine the half-lives of superheavy elements with Z=108-120 and neutron number N=152-190 to explore the long-standing predictions of the existence of an 'island of stability' due to possible spherical proton (Z{approx}114) and neutron (N{approx}184) shell closures.
27271627
Attractive holographic c-functions
A bstractUsing the attractor mechanism for extremal solutions in N=2$$ \mathcal{N}=2 $$ gauged supergravity, we construct a c-function that interpolates between the central charges of theories at ultraviolet and infrared conformal fixed points corresponding to anti-de Sitter geometries. The c-function we obtain is couched purely in terms of bulk quantities and connects two different dimensional CFTs at the stable conformal fixed points under the RG flow.