Hot Strange Hadronic Matter in an Effective Model

An effective model used to describe the strange hadronic matter with nucleons, Λ-hyperons, and Ξ-hyperonsis extended to finite temperature. The extended model is used to study the density, temperature, and strangeness fractiondependence of the effective masses of baryons in the matter. The thermodynamical quantities, such as free energy andpressure, as well as the equation of state of the matter, are given.     

Properties of Strange Matter in a Model with Effective lagrangian

The strange hadronic mater with nucleons,Λ-hyperons and Ξ-hyperons is studied by using an effective nuclear model in a mean-field approximation.The density and strangeness fraction dependence of the effective baryon masses as well as the saturation properties and stabilities of the strange hadronic matter are discussed.     

Strange hadronic matter in a modified quark-meson coupling model

Strange hadronic matter with nucleons, Λ-hyperons and Ξ-hyperons is studied by using a modified quark-meson coupling (MQMC) model in a mean-field approximation. The density dependence of the effective baryon masses as well as the saturation properties and stabilities of the strange hadronic matter are discussed.     

Spin-orbit coupling in Σ-hypernuclei

Single-particle energies of Σ-hyperons in _Σ¹⁶O are calculated within a relativistic mean-field theory. This model predicts a small spin-orbit splitting for Σ-hyperons in _Σ¹⁶O compared to ordinary nucleons in nuclei. Half of the small spin-orbit splitting is due to the anomalous magnetic moment of the Σ-hyperon. K and K¹ exchange terms are negligible. This is to be seen in contrast to a previous quark-model prediction of a strong spin-orbit splitting for hyperons.     

Neutrino scattering rates in the presence of hyperons from a Skyrme model in the RPA approximation

The contribution of -hyperons to neutrino scattering rates is calculated in the random phase approximation in a model where the interaction is described by a Skyrme potential. Finite temperature and neutrino trapping are taken into account in view of applications to the deleptonization stage of protoneutron star cooling. The hyperons can remove the problem of ferromagnetic instability common to (nearly) all Skyrme parametrizations of the nucleon-nucleon interaction. As a consequence, there is not any longer a pole at the transition in the neutrino-baryon cross-section. However there still remains an enhancement in this region. In the absence of ferromagnetism the mean free path in np matter is reduced compared to its value in np matter as a consequence of the presence of this additional degree of freedom. At high density the results are very sensitive to the choice of the - interaction.     

Spectra of Secondary Particles in High-Energy Proton–Proton Collisions in the Thermodynamic Model and the Possibility of Detection of Particles of Dark Matter

Physics of Atomic Nuclei - In a simple thermodynamic model, transverse momentum distributions are found for $$\Lambda $$ -hyperons produced in pp collisions at ultrarelativistic energies. Studying...     

A study of the C(p, p′) reactions at 135 MeV

A relativistic mean field approach is used to determine and compare the single-particle Dirac potentials for nuclei and hypernuclei (Λ, Σ, Ξ). A simple model is used and the Dirac-Hartree-Fock equations are reduced to a Schrödinger-like equation. The subsequent central and spin-orbit shell-model potentials are compared to those of phenomenological approach and other recent microscopic approaches. In the case of hypernuclei the Hartree approximation works already quite well without any need of taking into account the strangeness exchange part coming from strange mesons. The influence of the anomalous magnetic moment of the baryon on the spin-orbit term is found to be rather important for both Λ- and Σ-hyperons.     

核物质热力学系统的状态方程

用Bonn势和考虑强子质量Brown Rho(BR)标度规则修正,提出了改进的相对论平均场有效模型,由核物质的基态性质确定模型参数后,将该模型用来研究热密核物质系统的状态方程.     

Lowering Critical Temperature in the Extended Quark Sigma Model at Finite Temperature

A phase transition, a critical temperature, and meson masses are studied in the extended quark sigma model, in which the effective mesonic potential is extended to include eighth-order mesonic interactions. The second derivative of the effective mesonic potential is applied to calculate the effective sigma and pion masses as functions of temperature. We find that the critical temperature assumes a lower value in comparison with that of original quark sigma model. A comparison with recent calculations of lattice QCD is introduced. The behavior of the phase transition remains unchanged when the higher-order mesonic interactions are included. We find that the spontaneous symmetry-breaking condition is necessary to satisfy the Goldstone theorem at low temperatures.     

Phase transitions in dense quark matter in a gravitational field of constant curvature

Abstact The impact of the gravitational field on the formation of quark and diquark condensate in the framework of the extended Nambu-Jona-Lasinio (NJL) model is studied. In the mean field approximation, an expression for the effective potential with regard to a finite temperature and density of quark matter in the static gravitational field of constant curvature is obtained. Original Russian Text ? V.Ch. Zhukovsky, A.V. Tyukov, D. Ebert, 2007, published in Vestnik Moskovskogo Universiteta. Fizika, 2007, No. 3, pp. 68–70.     

核介质中强子性质的手征σ模型研究

采用手征σ模型描述核多体系统,考虑真空极化的影响,首先由核物质的饱和性质确定模型参数,进一步研究了强子性质在核介质中的变化。手征σ模型的研究结果给出,核子和ω介子的有效质量随核物质密度的增大而减小,但σ介子的有效质量随密度的增大而增大。这些结果与不满足手征对称性的Walecka模型结果进行了比较。计算中采用的重整化方法会对结果有一定的影响。The modification of hadron masses in nuclear medium is studied by using the chiral sigma model, which is extended to generate the omega meson mass by the sigma condensation in the vacuum in the same way as the nucleon mass. The chiral sigma model provides proper equilibrium properties of nuclear matter. It is shown that the effective masses of both nucleons and omega mesons decrease in nuclear medium, while the effective mass of sigma mesons increases at finite density in the chiral sigma model. The resuits obtained in the chiral sigma model are compared with those obtained in the Walecka model, which includes sigma and omega mesons in a non-chiral fashion.     

On the effective σ-boson exchange in the relativistic Dirac-Brueckner approach to nuclear matter

A relativistic form of the Brueckner theory of nuclear matter is applied to an extended meson-exchange model for the NN-interaction which contains explicit 2π-and π-exchange. This model avoids the effective σ-boson which is characteristic of the simplified meson exchange, as e.g. the one-boson-exchange (OBE) potential. It turns out that the relativistic saturation. effects found earlier within the OBE model are confirmed by the extended and more realistic model. In particular it is found that the relativistic effects caused by the explicit 2π-and π-exchange are well simulated by the effective σ-boson of the OBE model.     

Nuclear bound states of negatively charged hadrons?

The possibility that bound states of negatively charged kaons, antiprotons and Σ-hyperons might exist in nuclei is investigated. It is found that whilst such states could be bound their widths are sufficiently large as to probably prevent direct observation, except perhaps in a few specialised cases.     

Nuclear matter and neutron star properties with the extendedNambu-Jona-Lasinio model

An extended Nambu-Jona-Lasinio(eNJL) model with nucleons as the degrees of freedom is used to investigate properties of nuclear matter and neutron stars(NSs),including the binding energy and symmetry energy of the nuclear matter, the core-crust transition density, and mass-radius relation of NSs. The fourth-order symmetry energy at saturation density is also investigated. When the bulk properties of nuclear matter at saturation density are used to determine the model parameters, the double solutions of parameters are obtained for a given nuclear incompressibility. It is shown that the isovector-vector interaction has a significant influence on the nuclear matter and NS properties, and the sign of isovector-vector coupling constant is critical in the determination of the trend of the symmetry energy and equation of state. The effects of the other model parameters and symmetry energy slope at saturation density are discussed.     

Droplet formation in cold asymmetric nuclear matter

An extended version of the non-linear Walecka model, with ϱ mesons an electromagnetic field is used to investigate the possibility of phase transitions in cold nuclear matter (T = 0), giving rise to droplet formation. Surface properties of asymmetric nuclear matter as the droplet surface energy and its thickness are discussed. The effects of the Coulomb interaction are investigated.     

Spectroscopic Mapping of the Nonequilibrium between Electron and Excitation Temperatures in a 1 ATM Helium ARC

The thermostatic states of a 100 amp, 1.016 bar, free-burning helium short arc with a 10 mm electrode gap are mapped from spectroscopic measurements at eight cross sections. The theoretical model used is a multifluids model extended to consider nonequilibrium between electron and excitation temperatures, as well as simple nonequilibrium among excited electronic levels. Seven helium lines are used to determine population densities and upper level excitation temperatures. The electron density is calculated from continuum intensity measurements at C4690. Electron temperatures are found from an astrophysical method suggested by Athay and Menzel. The effective total excitation temperature is obtained by iteration using the multifluids model. The results indicate total excitation temperature values close to the usually calculated "LTE" temperatures, but electron temperatures up to three times larger than the total excitation temperature on the arc centerline near the electrodes. The ratio is approximately 1.5 in the middle of the arc. The heavy particle kinetic temperatures appear to follow the electron temperature, except near the anode, where they drop to values smaller than the total excitation temperatures.     

基于Savizky-Golay多项式的三维荧光光谱的曲面平滑方法

平滑处理是光谱分析中常用的预处理方法.在二维光谱分析中应用广泛的Savizky-Golay多项式曲线平滑方法并不能直接应用于三维荧光光谱的曲面平滑.文章针对三维荧光光谱提出了多项式平滑方法,从而将Savitzky-Golay多项式平滑方法扩展到三维荧光光谱,以解决曲面平滑问题.对基于三维荧光光谱的水体有机污染物浓度检测...     

Quark matter properties and fluctuations of conserved charges in (2+1)-flavored quark model

In this study, the susceptibilities of conserved charges, baryon number, charge number, and strangeness number at zero and low values of chemical potential are presented. Taylor series expansion was used to obtain results for the three-flavor Polyakov quark meson (PQM) model and the Polyakov loop extended chiral quark mean-field (PCQMF) model. Mean-field approximation was used to study quark matter with the inclusion of the isospin chemical potential, as well as the vector interactions. The effects of isospin chemical potential and vector-interactions on phase diagrams were analyzed. A comparative analysis of the two models was completed. Fluctuations of the conserved charges were enhanced in the transition temperature regime and hence provided information about the critical end point (CEP). Susceptibilities of conserved quantities were calculated by using the Taylor series method. Enhancement of fluctuations in the transition temperature neighborhood provided a clear signature of a quantum chromodynamics (QCD) critical-point.