120641266
$K^-$-Nuclear Bound States in Relativistic Mean-Field Theory
122686132
NEW AGEGRAPHIC CHAPLYGIN GAS MODEL WITH VISCOSITY
In this paper, motivated by Ref. 31, we study the so-called new agegraphic Chaplygin gas model with viscosity. Concretely, we establish the correspondence between the interacting new agegraphic dark energy (NADE) and variable generalized Chaplygin gas (VGCG) models in non-flat universe on the basis of reviewing related contents for the NADE and VGCG models. Furthermore, we reconstruct the potential of the new agegraphic scalar field as well as the dynamics of the scalar field according to the evolution of the agegraphic dark energy. Finally, we generalize our study to the case of NADE with viscosity, which includes the case without viscosity (ν = 0) as a special case.
123917430
ON KAON CONDENSATION IN DENSE NUCLEAR MATTER
The properties of kaons and antikaons in dense nuclear matter are investigated within the framework of relativistic mean-field theory including delta degrees of freedom. The couplings of kaon-baryon Interactions are determined by the chiral models. We find that the effective masses and energies of kaons and antikaons are reduced on account of the delta resonance in the nuclear matter. This mechanism may enhance the possibility of the existence of kaon condensation.
122935177
STRANGENESS PRODUCTION IN RELATIVISTIC NUCLEAR COLLISIONS
Quark matter produced in relativistic nuclear collisions is thermally equilibrated. A phenomenological model is used to calculate the yield of strange quark pairs at AGS, SPS and RHIC, which is comparable to the results from the experiments. In addition, analysis with this model indicates that there is a signal of phase transition where the cms energy is approximately 7.5 GeV.
119099744
Disk accretion flow driven by large-scale magnetic fields: Solutions with constant specific energy
(Abridged) We study the dynamical evolution of a stationary, axisymmetric, and perfectly conducting cold accretion disk containing a large-scale magnetic field around a Kerr black hole, trying to understand the relation between accretion and the transportation of angular momentum and energy. We solve the radial momentum equation for solutions corresponding to an accretion flow that starts from a subsonic state at infinity, smoothly passes the fast critical point, then supersonically falls into the horizon of the black hole. The solutions always have the following features: 1) The specific energy of fluid particles remains constant but the specific angular momentum is effectively removed by the magnetic field. 2) At large radii, where the disk motion is dominantly rotational, the energy density of the magnetic field is equipartitioned with the rotational energy density of the disk. 3) Inside the fast critical point, where radial motion becomes important, the ratio of the electromagnetic energy density to the kinetic energy density drops quickly. The results indicate that: 1) Disk accretion does not necessarily imply energy dissipation since magnetic fields do not have to transport or dissipate a lot of energy as they effectively transport angular momentum. 2) When resistivity is small, the large-scale magnetic field is amplified by the shearing rotation of the disk until the magnetic energy density is equipartitioned with the rotational energy density, ending up with a geometrically thick disk. This is in contrast with the evolution of small-scale magnetic fields where if the resistivity is nonzero the magnetic energy density is likely to be equipartitioned with the kinetic energy density associated with local random motions (e.g., turbulence), making a thin Keplerian disk possible.
125066933
FIELD MEASUREMENT OF SPEAR3 MAGNETS AT IHEP
The SPEAR3 storage ring comprises a total of 292 magnets which has four types and eight different effective magnetic lengths. The magnetic measurements of all the production magnets including 40 gradient dipoles, 102 quadrupoles with quadrupole modulation system (QMS) coils, 76 sextupoles with skew quadrupole trim coils and 74 dipole correctors combined H/V function, and their prototypes as well have been completed at IHEP successfully by the end of April, 2002. This paper covers the development of the measurement systems as well as the results of the magnetic measurements for SPEAR3 magnets at IHEP.
119237835
Dynamical Horizon Entropy Bound Conjecture in Loop Quantum Cosmology
The covariant entropy bound conjecture is an important hint for the quantum gravity, with several versions available in the literature. For cosmology, Ashtekar and Wilson-Ewing ever show the consistence between the loop gravity theory and one version of this conjecture. Recently, He and Zhang [J. High Energy Phys. 10(2007)077] proposed a version for the dynamical horizon of the universe,which validates the entropy bound conjecture for the cosmology filled with perfect fluid in the classical scenario when the universe is far away from the big bang singularity. However,their conjecture breaks down near big bang region. We examine this conjecture in the context of the loop quantum cosmology. With the example of photon gas,this conjecture is protected by the quantum geometry effects as expected.
39373169
Can the universe create itself
The question of first-cause has troubled philosophers and cosmologists alike. Now that it is apparent that our universe began in a Big Bang explosion, the question of what happened before the Big Bang arises. Inflation seems like a very promising answer, but as Borde and Vilenkin have shown, the inflationary state preceding the Big Bang must have had a beginning also. Ultimately, the difficult question seems to be how to make something out of nothing. This paper explores the idea that this is the wrong question --- that that is not how the Universe got here. Instead, we explore the idea of whether there is anything in the laws of physics that would prevent the Universe from creating itself. Because spacetimes can be curved and multiply connected, general relativity allows for the possibility of closed timelike curves (CTCs). Thus, tracing backwards in time through the original inflationary state we may eventually encounter a region of CTCs giving no first-cause. This region of CTCs, may well be over by now (being bounded toward the future by a Cauchy horizon). We illustrate that such models --- with CTCs --- are not necessarily inconsistent by demonstrating self-consistent vacuums for Misner space and a multiply connected de Sitter space in which the renormalized energy-momentum tensor does not diverge as one approaches the Cauchy horizon and solves Einstein's equations. We show such a Universe can be classically stable and self-consistent if and only if the potentials are retarded, giving a natural explanation of the arrow of time. Some specific scenarios (out of many possible ones) for this type of model are described. For example: an inflationary universe gives rise to baby universes, one of which turns out to be itself. Interestingly, the laws of physics may allow the Universe to be its own mother.