Showing papers on "Nuclear matter published in 1986"
TL;DR: In this article, a review of the recent progress in extracting the equation of state of hot dense hadronic matter from relativistic heavy ion collisions is presented, and a comparison of the distinct theoretical predictions to recent high multiplicity selected 4π data on fragment formation, pion production and collective sidewards flow is presented.
726 citations
TL;DR: In this article, it was shown that at somewhat higher densities one finds a charged kaon condensate, driven to a large extent by the stgma term interaction with baryons.
702 citations
TL;DR: In this article, a general Monte Carlo method was developed to study momentum distributions of nucleons and nucleon clusters in nuclei, which is used to calculate the momentum distribution of protons and neutrons in A = 3 and 4, d + p amplitudes in 3 He, and t + p and d + d amplitudes with improved variational wave functions.
281 citations
TL;DR: Theoretical models for the dynamics of the formation and emission of these clusters of nucleons are reviewed in this paper, but not all of them are statistical in origin, following from the assumption that the phase space available for cluster formation and emissions is the dominant factor.
270 citations
TL;DR: In this paper, a review of recent data on the production of pions and strange particles at the Bevalac and Synchrophasotron accelerators is presented, covering pion spectra and multiplicity distributions, λ, K+ and K− yields and spectra, and Λ polarization.
232 citations
TL;DR: This investigation investigates systematically the possibilities and the limits of the Skyrme force for reproducing nuclear ground-state properties in a spherical Hartree-Fock calculation by means of least-squares fits of the force parameters to the measured binding energy, diffraction radius, and surface width of eight selected nuclei.
Abstract: We investigate systematically the possibilities and the limits of the Skyrme force for reproducing nuclear ground-state properties in a spherical Hartree-Fock calculation. This investigation is performed by means of least-squares fits of the force parameters to the measured binding energy, diffraction radius, and surface width of eight selected nuclei. Particular emphasis is put on the density dependence of the interaction, which turns out to be determined mainly by the surface width. The least-squares fitting procedure yields the best-fit parameters together with uncertainties on them, and it also allows one to estimate the uncertainties of an extrapolation to other fields, e.g., nuclear matter properties. We also study the contribution of random-phase-approximation correlations to the ground-state properties and their influence on the parameters of the effective interaction. Here, we also compare to giant dipole resonance energies.
199 citations
TL;DR: In this article, the properties of cold and hot nuclear matter are studied in the frame of the Brueckner theory, extended to finite temperature, and a phenomenological treatment is performed.
132 citations
Book•
01 Jan 1986
TL;DR: In this article, the authors present a model of the Dirac nuclear structure in light nuclei using a Finite Range Dirac Interaction and a dynamical basis for NN Amplitudes and Dirac Optical Potentials.
Abstract: RELATIVISTIC DYNAMICS: Nonrelativistic and Relativistic Multiple Scattering The Meson Theory of Nuclear Forces and Nuclear Matter Electronuclear Reactions and Meson Exchange Currents Relativistic Meson-Nucleon Models: Applications to Bound and Scattering States Antiproton Physics at Intermediate Energy Development of the Dirac Scattering Approach Implications of Dirac Nuclear Structure for Electron Scattering A Relativistic Schematic Model of Nuclear Structure in Light Nuclei Studies of Nuclear Structure Using a Finite Range Dirac Interaction Relativistic and Nonrelativistic Dynamics in the (e,e'p) Reaction A Dynamical Basis for NN Amplitudes and Dirac Optical Potentials Relativistic vs Nonrelativistic Models of Proton-Nucleus Inelastic Scattering Recent Experimental Results in (e,e'p) Antiprotons Are Another Matter QUARK-NUCLEAR PHYSICS: Deep Inelastic Scattering with Application to Nuclear Targets Nuclear Physics from the Quark Model with Chromodynamics Hadronic Matter on a Lattice Low Energy Phenomenology with Skyrmions Nuclear Force in a Quark Model Two Baryon Systems in the Nonrelativistic Quark Model Covariant Condensate Wave Functions in the Skyrme Model Nuclei in the Skyrme Model.
121 citations
TL;DR: In this article, a three-phase model of strongly interacting matter was considered, where each phase was treated as an ideal gas modified by a simple phenomenological interaction feature for nuclear matter, taking into account the baryonic repulsion.
Abstract: We consider a three-phase model of strongly interacting matter, treating each phase as an ideal gas modified by a simple phenomenological interaction feature For nuclear matter, we take into account the baryonic repulsion; for the quark-gluon plasma, we include the bag pressure; the constituent quark phase has a non-zero effective quark mass as well as an independent bag pressure By studying which phase dominates thermodynamically in what region of temperature and baryon number density, we obtain a phase diagram for strongly interacting matter and gain some insight on the relation between deconfinement and chiral symmetry restoration
75 citations
TL;DR: The method of thermodynamic Green's functions is applied to a nonrelativistic many-quark model system and it is shown that beyond a critical density the nucleonic clusters are dissolved due to the Pauli quenching effects.
Abstract: The method of thermodynamic Green's functions is applied to a nonrelativistic many-quark model system. A color-saturated confinement interaction is introduced by considering nearest-neighbor string configurations. The equation of state which accounts for the formation of three-particle bound states is derived within a ladder Hartree-Fock approximation. The temperature- and density-dependent energy shift of the intrinsic nucleonic system is calculated by considering the exchange symmetry (Pauli principle) between the quark constituents of the nucleons. The relation of this nucleonic quasiparticle energy shift to nuclear-matter data is pointed out. It is shown that beyond a critical density the nucleonic clusters are dissolved due to the Pauli quenching effects. The hadronic-to-quark-matter phase transition is considered at zero temperature.
69 citations
TL;DR: Isotherms in a P-rho diagram are obtained which show the existence of a liquid-vapor phase equilibrium below a critical temperature of T/sub c/approx.
Abstract: Within the framework of the relativistic Dirac-Brueckner approach, the equation of state of nuclear matter is studied on the basis of a one-boson-exchange interaction. The saturation properties of the ground state and its compressional energy are calculated. The model is extended to nonzero temperature by use of finite-temperature Green's functions for the dressed nucleons. Isotherms in a $P\ensuremath{-}\ensuremath{\rho}$ diagram are obtained which show the existence of a liquid-vapor phase equilibrium below a critical temperature of ${T}_{c}\ensuremath{\simeq}12$ MeV.
01 Jan 1986
TL;DR: In this paper, a survey of methods used and results obtained in Monte Carlo calculations on quantum fluids and crystals is presented, and the reliability of the product form of ψT in several applications is assessed.
Abstract: We review methods used and results obtained in Monte Carlo calculations on quantum fluids and crystals. Available techniques are discussed for the computation of the energy and other expectation values by variational methods in which the absolute square of a trial function ψT is sampled by the Metropolis method. Recently developed methods for fermion systems are included. We give a more detailed exposition of the Green’s Function Monte Carlo method which permits exact numerical estimates of boson ground-state properties. Our survey of results comprises applications to 3He and 4He, hard-sphere fluids and crystals, spin-aligned hydrogen, the one-component plasma for bosons and fermions, and simple models of neutron and nuclear matter. The reliability of the product form of ψT in several applications is assessed. A selected set of related topics is also taken up: low temperature excitations, results obtained by the Wigner ℏ expansion, and evaluations of virial coefficients and pair correlations at finite temperatures.
01 Jan 1986
TL;DR: The proceedings of the NATO Workshop on Nycleosynthesis, held in March 1985 in Les Arcs, France, are presented and discussed in this article, which assembles the most recent discoveries and progresses in the field.
Abstract: Nuclear astrophysics explains the formation of the chemical element and the evolution of the composition of observable matter. This topic is obviously related to various aspects of nuclear physics (nuclear cross-sections, nuclear excited states, masses and life times). It is also very closely linked to many aspects of particle physics: Big Bang theories, nature of the dark matter of the Universe, existence of quarked nuclei, etc. All theses aspects are presented and discussed in this book, which assembles the most recent discoveries and progresses in the field. It is the proceedings of the NATO Workshop on Nycleosynthesis, held in March 1985 in Les Arcs, France.
TL;DR: The present status of theoretical descriptions of non-mesonic decay modes of hypernuclei is reviewed in this article, where one model which evaluates a strangeness-changing, parity-violating weak interaction potential in nuclear matter is examined in detail to exemplify the physics which can be learned and the problems which must be confronted.
TL;DR: The observed masses of neutron stars are used to shed some light on the current controversy concerning the value of the nuclear compression modulus and it is found that values less than about 200 MeV are incompatible with the observed masses.
Abstract: The observed masses of neutron stars are used to shed some light on the current controversy concerning the value of the nuclear compression modulus. We find that values less than about 200 MeV are incompatible with the observed masses.
TL;DR: Optical potentials and mean free paths of nucleons at finite temperatures are studied by utilizing effective Skyrme interactions which yield "good" optical potentials at zero temperature as mentioned in this paper, and the results for nuclear matter (symmetric and asymmetric) are applied within the local density approximation to finite nuclei at various temperatures.
TL;DR: In this article, effective interactions based on a Brueckner G -matrix in nuclear matter were used to calculate Gamow-Teller strength distributions in 48 Ca, 90 Zr and 208 Pb in local density approximation.
TL;DR: In this paper, a thermodynamically consistent treatment of the nuclear interaction is employed to study the dependence of pion production on the nuclear equation of state in heavy-ion collisions, and the measured pion multiplicities, which vary over eight orders of magnitude in the bombarding energy range from 30 MeV/nucleon to 4 GeV/Nucleon, are reproduced within a simple one-dimensional fluiddynamical model if it is assumed that nuclear matter is rather incompressible.
TL;DR: In this paper, a relativistic Dirac-Brueckner approach was used to calculate the nucleon self-energy above the nuclear-matter Fermi sea.
TL;DR: It is demonstrated that the charge-distribution differences between isotopes of heavy-mass nuclei are the most sensitive experimental quantities for extraction of the compression modulus of nuclear matter.
Abstract: We demonstrate that the charge-distribution differences between isotopes of heavy-mass nuclei are the most sensitive experimental quantities for extraction of the compression modulus of nuclear matter. This analysis shows a compression modulus larger than 200 MeV.
TL;DR: The disassembly of hot classical charged drops containing \ensuremath{\sim}230 and 130 particles is studied with the molecular dynamics method, and the strength of the Coulomb repulsion is chosen so that these drops have a binding energy formula similar to that of nuclei.
Abstract: The disassembly of hot classical charged drops containing \ensuremath{\sim}230 and 130 particles is studied with the molecular dynamics method. The strength of the Coulomb repulsion is chosen so that these drops have a binding energy formula similar to that of nuclei. The phase diagram of neutral matter, obtained by switching off the Coulomb force, is also similar to that of nuclear matter. In addition to the total-vaporization, fragmentation, and evaporation modes of the disassembly of neutral drops, the charged drops also break by multiple and binary fission. The liquid-gas phase transition plays an important role in the multiple fission of expanding charged liquid drops. There also appears to be a window in the initial conditions in which binary fission followed by a density oscillation is the dominant mode of breakup. The multiple and binary fission breakups are due to the Coulomb forces, and they yield more massive clusters with relatively few small clusters with \ensuremath{\sim}10 particles. The higher energy fragmentation and total vaporization modes are not significantly influenced by the Coulomb forces. They are primarily due to the liquid-gas transition, and their yields decrease almost monotonically with the number of particles in the cluster.
TL;DR: The photon cross section calculated with a zero range np interaction agrees well with measurements on proton-induced reactions, and for heavy-ion reactions, the initial np collisions only account for a third of the measured cross section.
Abstract: High energy photons may be produced in nuclear reactions by several mechanisms, including bremsstrahlung from the potential field or from nucleon-nucleon collisions. Using infinite and semi-infinite nuclear matter approximations, we obtain simple expressions for the rates. Nucleon-nucleon collisions provide the more important mechanism for both proton-induced and heavy-ion induced reactions, except for the highest energy photons. The photon cross section calculated with a zero range np interaction agrees well with measurements on proton-induced reactions. For heavy-ion reactions, the initial np collisions only account for a third of the measured cross section. The disagreement may be due to an inadequacy of the infinite matter or the zero range approximations, or it may be that multiple collisions are important.
TL;DR: In this article, the π+A → π +π+A' and π−A → ε+π−A' inclusive reactions are studied theoretically avoiding approximations known to be not too accurate.
TL;DR: Calculations of magnetic moments for closed shell plus (or minus) one nucleon using this effective current operator recover the Schmidt values, thus resolving a longstanding problem with relativistic models of nuclear structure.
Abstract: A Landau-Migdal approach to relativistic mean field theory of nuclear matter is used to define the single particle isoscalar current. By virtue of the near cancellation of scalar and vector potentials, this current is very close to the standard nonrelativistic isoscalar current; and hence the single particle isoscalar magnetic moment operator gives results in agreement with the nonrelativistic shell model. Calculations of magnetic moments for closed shell plus (or minus) one nucleon using this effective current operator recover the Schmidt values, thus resolving a longstanding problem with relativistic models of nuclear structure.
TL;DR: In this paper, the Vlasov-Uehling-Uhlenbeck theory is used to predict the bounce-off effect of the projectile fragments and the sidewards flow of the participant matter.
TL;DR: In this article, the momentum distribution of protons in 208 Pb is investigated in the framework of a model in which the ground-state wave function is specified by the occupation probabilities of shell-model orbits.
TL;DR: In this article, the Coulomb repulsion was used to explain a shift in the form factor zero of all measured charge distributions as compared to a simple folding model, leading to an increase in the surface width of nuclear charge distributions by 0.105 fm.
TL;DR: The Coulomb sum value for electron scattering is estimated using the relativistic random phase approximation (RPA) in the field theory for nuclear matter as discussed by the authors, which reduces the sum value of the Hartree approximation by about 15-20%.
TL;DR: In this paper, an extended skyrmion model was derived from the effective chiral meson lagrangian derived from Nambu-Jona-Lasinio type of quark flavour dynamics, which contains besides the usual Skyrme term further fourth-order derivative terms of the chiral field and in addition the ω meson field.