Showing papers on "Nuclear matter published in 1985"
TL;DR: In this paper, the Lagrangian field theory of interacting nucleons, hyperons, and mesons is applied to neutron stars in the mean field approximation to account for the four bulk properties of nuclear matter; saturation binding and density, compressibility, and charge symmetry energy.
Abstract: Neutron stars are studied in the framework of Lagrangian field theory of interacting nucleons, hyperons, and mesons, which is solved in the mean field approximation The theory is constrained to account for the four bulk properties of nuclear matter; the saturation binding and density, compressibility, and charge symmetry energy The cores of the heavier neutron stars are found to be dominated by hyperons, and the total hyperon population for such stars is 15%--20%, depending on whether pions condense or not The rho-meson, which contributes to the isospin symmetry energy, has an important influence on the baryon populations Lepton populations are strongly suppressed and charge neutrality is achieved among the hadrons A possible consequence for the decay time of the magnetic field of pulsars and hence for their active lifetime is mentioned
574 citations
TL;DR: Transport coefficients of small-chemical-potential quark-gluon plasmas are estimated and dissipative corrections to the scaling hydrodynamic equations for ultrarelativistic nuclear collisions are studied.
Abstract: Transport coefficients of small-chemical-potential quark-gluon plasmas are estimated and dissipative corrections to the scaling hydrodynamic equations for ultrarelativistic nuclear collisions are studied. The absence of heat-conduction phenomena is clarified. Lower and upper bounds on the shear-viscosity coefficient are derived. QCD phenomenology is used to estimate effects of color-electric and -magnetic shielding, and nonperturbative antiscreening. Bulk viscosity associated with the plasma-to-hadron transition is estimated within the relaxation-time approximation. Finally, effects of dissipative phenomena on the relation between initial energy density and final rapidity density are estimated.
333 citations
TL;DR: The theoretical and experimental evidence which testifies to the existence of a strong energy dependence of this effective mass around the Fermi energy and near the nuclear surface is the central subject of the present review.
295 citations
TL;DR: The production of kaons at subthreshold energies from heavy-ion collisions is sensitive to the nuclear equation of state and the Boltzmann-Uehling-Uhlenbeck model is used to model this phenomenon.
Abstract: The production of kaons at subthreshold energies from heavy-ion collisions is sensitive to the nuclear equation of state. In the Boltzmann-Uehling-Uhlenbeck model, the number of produced kaons from central collisions between heavy nuclei at incident energies around 700 MeV/nucleon can vary by a factor of \ensuremath{\sim} 3, depending on the equation of state.
232 citations
TL;DR: The applicability of the Skyrme model to the analysis of nuclear matter is discussed in this article, where an ansatz that describes a cubic skyrmion crystal is presented.
211 citations
TL;DR: In this article, the thermodynamic properties of hot, dense matter are examined in the density range 10 −5 fm −3 ⩽ n⩽ 0.35 fm−3 and the temperature range 0 −2 T −21 MeV, for fixed lepton fractions Y l = 0.4, 0.3 and 0.2.
188 citations
TL;DR: In this article, a new statistical approach is adopted which, through a suitable analysis of light clusters emitted in heavy-ion collisions, allows us to evaluate temperature and free-nucleon densities of the emission source.
Abstract: A new statistical approach is adopted which, through a suitable analysis of light clusters emitted in heavy-ion collisions, allows us to evaluate temperature and free-nucleon densities of the emission source. All known data concerning the emission of2H,3H,3He,4He measured in a common experiment are used. These data refer to 19 heavy-ion reactions studied at projectile energies between 26 and 2100 MeV per nucleon. Analysed events are only those attributable to the equilibrium component through carefully adopted selections. Among the results, a correlation is observed between temperatureT and total free-nucleon density ϱt
F of the emission source. A nuclear-matter model is formulated in order to compare its quantitative predictions with the observed (T, ϱ
t
F) correlation. A good agreement is found by this comparison.
182 citations
TL;DR: In this article, temperature-dependent Hartree-Fock calculations for equilibrated hot nuclei are presented, extending to the highest temperatures at which the nuclei remain stable and the Coulomb repulsion causes a nucleus to become electrostatically unstable and to fall apart at much lower temperatures than its uncharged partner.
165 citations
138 citations
TL;DR: In this article, the thermal emission of photons and lepton pairs from quark matter formed in ultrarelativistic nuclear collisions are related to the conserved total entropy of the quark.
Abstract: The rates of thermal emission of photons and lepton pairs from quark matter formed in ultrarelativistic nuclear collisions are related to the conserved total entropy of the quark matter. The transient existence of quark matter can be diagnosed by measuring the entropy separately from particle multiplicities and comparing the predicted and observed rates. The thermal soft-multiple-scattering rates are compared with the direct hard-single-scattering rates. Transverse-momentum effects, the background due to DD¯→μμ¯X decays, and fluctuations are discussed.
137 citations
TL;DR: In this article, the zero-temperature equation of state of isospin-symmetric nuclear matter below saturation density was studied by minimizing the energy of the nucleons in a periodic cubic cell at each mean density.
TL;DR: In this article, it is shown that thermal and chemical equilibrium are approached during the high density stage in central nucleus-nucleus collisions and that the yield of produced pions is determined at that time.
TL;DR: It is conjectured here that the characterization of the plasma as a free or weakly interacting gas of quarks and gluons is valid only for short distances and short time scales of the order 1/T, but that at scales larger than 1/g/sup 2/T the plasma exhibits confining features similar to that of the low-temperature hadronic phase.
Abstract: It is a widely held belief that at temperatures much higher than the confinement scale of quantum chromodynamics (QCD), quarks and gluons become free, giving rise to a new form of matter, called the quark-gluon plasma. It is conjectured here that the characterization of the plasma as a free or weakly interacting gas of quarks and gluons is valid only for short distances and short time scales of the order 1/T, but that at scales larger than 1/${g}^{2}$T (where ${g}^{2}$ is the running QCD coupling) the plasma exhibits confining features similar to that of the low-temperature hadronic phase. The confining features are manifest in the long-range, i.e., long-wavelength, low-frequency, modes of the plasma. To examine the long-range real-time response of the plasma goes beyond the capabilities of current lattice-gauge-theory techniques. However, some properties of these modes can be determined indirectly. An attempt is made to characterize the long-range modes of excitation by examining the static high-temperature limit, focusing upon the static screening lengths of colored and neutral local operators. Since ${g}^{2}$ is not small at temperatures likely to be accessible in heavy-ion collisions, the nonperturbative effects associated with vestiges of confinement are likely to be important in the phenomenological analysis of measurements made at accelerators.
TL;DR: In this paper, the mesonic and non-mesonic decay width of Λ-hypernuclei were studied by performing calculations in nuclear matter and using the local density prescription to apply the results to finite nuclei.
TL;DR: In this article, the authors investigated the Coulomb instability in a hot compound nucleus when its temperature is raised beyond a certain limiting value and demonstrated the relation between this instability and the liquid-gas phase transition occurring in hot nuclear matter.
01 Jan 1985
TL;DR: In this article, the nuclear as a Skyrmion bag, nuclear forces in the light of QCD, relativistic description of few body systems, nuclear compton scattering, and delta excitation in nuclei by pions and photons are discussed.
Abstract: This book presents papers on nuclear physics at intermediate energies Topics covered include the nuclear as a Skyrmion bag, nuclear forces in the light of QCD, relativistic description of few body systems, nuclear compton scattering, and delta excitation in nuclei by pions and photons
TL;DR: It is concluded that the stopping domain for central collisions of heavy ions extends up to center-of-mass kinetic energies E/sub c.m./roughly-equal(3 +- 1)A GeV.
Abstract: Recent p+A..-->..p+X data are analyzed within the context of the multichain and additive quark models. We deduce the average energy loss of a baryon as a function of distance traversed in nuclear matter. Consistency of the multichain model is checked by comparing the predictions for p+A..--> pi../sup + -/+X with data. We discuss the space-time development of baryon stopping and show how longitudinal growth limits the energy deposition per unit length. Predictions are made for the proton spectra to be measured in nucleus-nucleus collisions at CERN and BNL. Finally, we conclude that the stopping domain for central collisions of heavy ions extends up to center-of-mass kinetic energies E/sub c.m./roughly-equal(3 +- 1)A GeV.
TL;DR: The novel momentum analysis technique introduced by Danielewicz and Odyniec can be used to detect and exhibit collective flow in the light system Ar(1800 MeV/nucleon) + KCl where the usual kinetic energy flow analysis fails.
Abstract: The novel momentum analysis technique introduced by Danielewicz and Odyniec can be used to detect and exhibit collective flow in the light system Ar(1800 MeV/nucleon) + KCl where the usual kinetic energy flow analysis fails. The microscopic Vlasov-Uehling-Uhlenbeck theory which includes the nuclear mean field, two-body collisions, and Pauli blocking is used to study this phenomenon. The resulting transverse momentum transfers turn out to be quite sensitive to the nuclear equation of state. From a comparison with experimental data, evidence is presented for a rather stiff nuclear equation of state. The cascade model is unable to describe the data.
TL;DR: It appears unlikely that fragmentation of small drops (nuclei) can be used to study the isothermal critical region of gas-liquid phase transition, and a detailed tabulation of the energies and number of monomers, dimers, light, and heavy fragments emitted in each event is presented.
Abstract: Time evolution of hot drops of matter containing approx.230 or approx.130 particles is studied by classical molecular dynamics. Initially, the drops have uniform density and a sharp surface. The chosen initial conditions include three values of density and a range of temperatures wide enough to study the phenomena of evaporation, fragmentation, and total vaporization in a unified fashion. The average density and temperature of central matter is measured periodically to obtain trajectories of the evolution in the rho,T plane. These trajectories indicate that the matter expands almost adiabatically until it reaches the region of adiabatic instabilities. Density inhomogeneities develop in this region, but the matter fragments only if the expansion continues to average densities of less than one-fourth the liquid density, otherwise it recondenses into a single blob. The recondensed matter and fragments have very crooked surfaces. If the temperature is high enough, the expanding matter does not enter the region of adiabatic instabilities and totally vaporizes. For initial densities of the order of equilibrium density, matter does not fragment or develop large inhomogeneities in the region enclosed by the isothermal and adiabatic spinodals. Thus it appears unlikely that fragmentation of small drops (nuclei) can be used to study themore » isothermal critical region of gas-liquid phase transition. A detailed tabulation of the energies and number of monomers, dimers, light, and heavy fragments emitted in each event is presented.« less
TL;DR: In this article, the spin-isospin-dependent response function of nuclear matter at high excitation energies is investigated and its implications for the high-energy (3 He, t) reaction are studied.
TL;DR: The kinetic equations for production in hot nuclear matter of rare, strange antibaryons are studied numerically in this paper, where they are confirmed as viable characteristic signatures of the quark-gluon plasma.
TL;DR: In this article, a microscopic parameter-free calculation of the heavy-ion optical potential is presented, assuming the dominance of nucleon-nucleon collisions in the reaction dynamics, a description of these processes is translated into a two-Fermi-sphere nuclear matter picture, using a generalized local-density approximation.
TL;DR: In this article, the authors used the extended Thomas-Fermi approximation and Skyrme-type interactions to describe the energy density of a semi-infinite slab of neutron-rich nuclear matter at zero temperature.
TL;DR: The compression modulus of nuclear matter is determined from Fermi liquid parameters and the Landau sum rule to be K ⩽ 106 MeV, which is only about half of the commonly accepted value.
TL;DR: The entropy production extrapolated for infinite nuclear matter is independent of target-projectile combination at 400 MeV/nucleon and changes little with increasing bombarding energy, but the absolute values are strongly model dependent.
Abstract: The particle production (p,d,t${,}^{3}$He${,}^{4}$He) was studied for 400 and 650 MeV/nucleon Nb+Nb and 400 and 1050 MeV/nucleon Ca+Ca. The chemical freeze-out density of the participants and the entropy produced were deduced for each system. The chemical freeze-out densities are close to normal nuclear density. The entropy production extrapolated for infinite nuclear matter is independent of target-projectile combination at 400 MeV/nucleon and changes little with increasing bombarding energy, but the absolute values are strongly model dependent. The low entropy, when compared to fireball calculations, indicates that compression is present in the collisions. Therefore entropy values in principle can help in the determination of the equation of state for nuclear matter.
TL;DR: In this article, two commonly used non-equivalent ways of defining the surface energy of a multi-component system are discussed, both for a single-phase (isolated) system and for a two-phase system such as nuclei immersed in a neutron gas.
TL;DR: In this article, the transition between one-and two-body processes in intermediate-energy heavy-ion collisions is studied using the Landau-Vlasov equation for nucleons in the nuclear matter.