6894202
The Cosmological Quark-Hadron Transition and Massive Compact Halo Objects
One of the abiding mysteries in the so-called standard cosmological model is the nature of the dark matter. It is universally accepted that there is an abundance of matter in the universe which is non-luminous, due to their very weak interaction, if at all, with the other forms of matter, excepting of course the gravitational attraction. Speculations as to the nature of dark matter are numerous, often bordering on exotics, and searches for such exotic matter is a very active field of astroparticle physics at the dawn of the new century. Nevertheless, in recent years, there has been experimental evidence for at least one form of dark matter - the massive compact halo objects detected through gravitational microlensing effects proposed by Paczynski some years ago. To date, no clear consensus as to what these objects, referred to in the literature as well as in the following by the acronym MACHO, are made of; for a brief discussion of some of the suggestions, see below. In this work, we show that they find a natural explanation as leftover relics from the putative first order cosmic quark - hadron phase transition that is predicted by the standard model of particle interactions to have occurred during the microsecond epoch of the early universe.
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.
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.
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.
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.
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}
41364893
On entanglement entropy functionals in higher-derivative gravity theories
A bstractIn arXiv:1310.5713 [1] and arXiv:1310.6659 [2] a formula was proposed as the entanglement entropy functional for a general higher-derivative theory of gravity, whose lagrangian consists of terms containing contractions of the Riemann tensor. In this paper, we carry out some tests of this proposal. First, we find the surface equation of motion for general four-derivative gravity theory by minimizing the holographic entanglement entropy functional resulting from this proposed formula. Then we calculate the surface equation for the same theory using the generalized gravitational entropy method of arXiv:1304.4926 [3]. We find that the two do not match in their entirety. We also construct the holographic entropy functional for quasi-topological gravity, which is a six-derivative gravity theory. We find that this functional gives the correct universal terms. However, as in the R2 case, the generalized gravitational entropy method applied to this theory does not give exactly the surface equation of motion coming from minimizing the entropy functional.
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.