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.
119255736
Determining Nuclear Form factor for Detection of Dark Matter in Relativistic Mean Field Theory
In this work, we derive the nuclear form factor for the spin-independent collision between the WIMPs and nucleus in terms of the relativistic mean field (RMF) theory. Comparison with the traditional form factors which are commonly used in literature is given and it is found that our results are slightly above that of the 2PF model by 4% to 8%, but deviate from the Helm form factor by 15% to 25% for the whole recoil energy spectrum of 0 ~ 100 keV. Moreover, taking Xe and Ge as examples, we show the dependence of the form factor on the recoil energy.
124229961
A light-cone QCD inspired effective Hamiltonian model for pseudoscalar and scalar mesons
Considering the one-gluon exchange interaction and phenomenological quark confinement potential, an improved light-cone effective Hamiltonian for mesons and the corresponding radial mass eigen equations in angular momentum representation is obtained. Solving the J = 0 eigen equations numerically and using a set of adjustable parameters, the obtained solutions for ground states and radial excited states can simultaneously describe both pseudoscalar and scalar flavour-off-diagonal mesons. Some radial excited states are also predicted and wait for experimental test. More results for the vector and axial vector mesons are expected.
122969926
K− Nucleus Elastic Scattering and Momentum-Dependent Optical Potentials
The K− nucleus differential elastic scattering cross section for 12C and 40Ca at is calculated with three momentum-dependent optical potential models, which are density-dependent, relativistic mean field, and hybrid model, respectively. It is found that the forms of momentum-dependent optical potential models proposed by us are reasonable and gain success in the calculations and the momentum-dependent hybrid model is the best model for the K− nucleus elastic scattering.
122405140
Effects of Delta Degrees of Freedom on Quark Condensate in Hot and Dense Matter
The relativistic mean-field theory is applied to study the quark condensate systematically in nuclear matter at zero and finite temperature in terms of the relative importance of delta degrees of freedom. Calculations have included the high-order contributions to quark condensate in nuclear medium due to the baryon-baryon interactions. Numerical results are presented for the nuclear density up to five times larger than the normal density and temperature up to 120 MeV. It is found that the delta resonance in nuclear matter can cause substantial decreases to in-medium quark condensate.
116062458
eta mesons in nuclear matter
The {eta}-nucleon ({eta}N) interactions are deduced from the heavy-baryon chiral perturbation theory to the next-to-leading-order terms. Combining the relativistic mean-field theory for nucleon system, we have studied the in-medium properties of the {eta} meson. We find that all the elastic-scattering {eta}N interactions come from the next-to-leading-order terms. The {eta}N sigma term is found to be about 280 {+-} 130 MeV. The off-shell terms are also important to the in-medium properties of the {eta} meson. On application of the latest determination of the {eta}N scattering length, the ratio of the {eta}-meson effective mass to its vacuum value is near 0.84{+-}0.015, whereas the optical potential is about -(83{+-}5) MeV, at the normal nuclear density.
55133202
Entanglement entropy in a holographic p-wave superconductor model
In a recent paper, arXiv:1309.4877, a holographic p-wave model has been proposed in an Einstein– Maxwell-complex vector field theory with a negative cosmological constant. The model exhibits rich phase structure depending on the mass and the charge of the vector field. We investigate the behavior of the entanglement entropy of dual field theory in this model. When the above two model parameters change, we observe the second order, first order and zeroth order phase transitions from the behavior of the entanglement entropy at some intermediate temperatures. These imply that the entanglement entropy can indicate not only the occurrence of the phase transition, but also the order of the phase transition. The entanglement entropy is indeed a good probe to phase transition. Furthermore, the “retrograde condensation” which is a sub-dominated phase is also reflected on the entanglement entropy. © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP 3 .
17840889
The evolutionary status of W Ursae Majoris‐type systems
Well-determined physical parameters of 130 W Ursae Majoris (W UMa) systems were collected from the literature. Based on these data, the evolutionary status and dynamical evolution of W UMa systems are investigated. It is found that there is no evolutionary difference between W- and A-type systems in the M-J diagram, which is consistent with the results derived from the analysis of observed spectral type and of M-R and M-L diagrams of W UMa systems. M-R and M-L diagrams of W- and A-type systems indicate that a large amount of energy should be transferred from the more massive to the less massive component, so that they are not in thermal equilibrium and undergo thermal relaxation oscillation. Moreover, the distribution of angular momentum, together with the distribution of the mass ratio, suggests that the mass ratio of the observed W UMa systems decreases with decreasing total mass. This could be the result of the dynamical evolution of W UMa systems, which suffer angular momentum loss and mass loss as a result of the magnetic stellar wind. Consequently, the tidal instability forces these systems towards lower q values and finally to rapidly rotating single stars.
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.
15595923
VACUUM POLARIZATION IN AN ANTI-DE SITTER SPACE AS AN ORIGIN FOR A COSMOLOGICAL CONSTANT IN A BRANE WORLD
We show that the vacuum polarization of quantum fields in an anti-de Sitter space can naturally give rise to a small but nonzero cosmological constant in a brane world living in it. To explain the extremely small ratio of mass density in the cosmological constant to the Planck mass density in our universe (≈10-123) as suggested by cosmological observations, all we need is a four-dimensional brane world (our universe) living in a five-dimensional anti-de Sitter space with a curvature radius r0~10-3cm and a fundamental Planck energy MP~109GeV, and a scalar field with a mass $m\sim r^{-1}_0\sim 10^{-2} {\rm eV}$. Probing gravity down to a scale ~10-3 cm, which is attainable in the near future, will provide a test of the model.
119198410
Loop quantum cosmology with higher order holonomy corrections
With a well-motivated extension of higher order holonomy corrections, the quantum theory of loop quantum cosmology (LQC) for the $k=0$ Friedmann-Robertson-Walker model (with a free massless scalar) is rigorously formulated. The analytical investigation reveals that, regardless of the order of holonomy corrections and for any arbitrary states, the matter density remains finite, bounded from above by an upper bound, which equals the critical density obtained at the level of heuristic effective dynamics. Particularly, with all orders of corrections included, the dynamical evolution is shown to follow the bouncing scenario in which two Wheeler-DeWitt solutions (expanding and contracting) are bridged together through the quantum bounce. These observations provide further evidence that the quantum bounce is essentially a consequence of the intrinsic discreteness of LQC and LQC is fundamentally different from the WDW theory. Meanwhile, the possibility is also explored so that the higher order holonomy corrections can be interpreted as a result of admitting generic $SU(2)$ representations for the Hamiltonian constraint operators.