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Nuclear matter

About: Nuclear matter is a research topic. Over the lifetime, 10180 publications have been published within this topic receiving 248261 citations.


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TL;DR: In this article, the effects of the density-dependent symmetry potential for baryons and of the Coulomb potential for produced mesons are investigated for neutron-rich heavy ion collisions at intermediate energies.
Abstract: Based on the ultrarelativistic quantum molecular dynamics model, the effects of the density-dependent symmetry potential for baryons and of the Coulomb potential for produced mesons are investigated for neutron-rich heavy ion collisions at intermediate energies. The calculated results of the Δ−/Δ++ and π−/π+ production ratios show a clear beam-energy dependence on the density-dependent symmetry potential, which is stronger for the π−/π+ ratio close to the pion production threshold. The Coulomb potential of the mesons changes the transverse momentum distribution of the π−/π+ ratio significantly, though it alters only slightly the π− and π+ total yields. The π− yields, especially at midrapidity or at low transverse momenta and the π−/π+ ratios at low transverse momenta are shown to be sensitive probes of the density-dependent symmetry potential in dense nuclear matter. The effect of the density-dependent symmetry potential on the production of both K0 and K+ mesons is also investigated.

64 citations

Journal ArticleDOI
TL;DR: In this article, a model to describe dense hadronic matter at zero and finite temperature, based on the parity doublet model of DeTar and Kunihiro, with including the iso-singlet scalar meson σ as well as ρ and ω mesons, is presented.
Abstract: We construct a model to describe dense hadronic matter at zero and finite temperature, based on the parity doublet model of DeTar and Kunihiro, with including the iso-singlet scalar meson σ as well as ρ and ω mesons. We show that, by including a six-point interaction of σ meson, the model reasonably reproduces the properties of the normal nuclear matter with the chiral invariant nucleon mass m0 in the range from 500 MeV to 900 MeV. Furthermore, we study the phase diagram based on the model, which shows that the value of the chiral condensate drops at the liquid-gas phase transition point and at the chiral phase transition point. We also study asymmetric nuclear matter and find that the first order phase transition for the liquid-gas phase transition disappears in asymmetric matter and that the critical density for the chiral phase transition at non-zero density becomes smaller for larger asymmetry. PACS numbers: 21.65.Cd,21.65.Mn,12.39.Fe I. INTRODUCTION With the advent of next generation radioactive beam facilities isospin asymmetric nuclear matter claims much attention in contemporary nuclear physics. At those facilities we could create terrestrial environment to study dense matter with a large neutron or proton excess through nuclear reactions with radioactive nuclei. Studying nuclear matter is also important to understand the structure of neutron stars [1]. In 2010 and 2013, two neutron stars with twice solar mass were found [2, 3] and many models yielding the soft equation of states (EOS) were excluded. Neutron stars offer very cold and asymmetric dense environment and may have hyperons in the core of the stars. If there are hyperonic degrees of freedom, it is expected that the EOS becomes softer and neutron star mass becomes lighter. Another important astrophysical site for nuclear matter is a hybrid star whose center has quark matter [4]. The properties of asymmetric matter have been investigated in various approaches [5–14]. Very recently liquid-gas and chiral phase transition are studied in a parity doublet model with a six-point scalar interaction in which mesonic fluctuations are included by means of the functional renormalization group [15]. In this work we study isospin asymmetric dense matter in the framework of the parity doublet model (mirror assignment) [16, 17]. The properties of symmetric dense matter such as chiral phase transition were extensively studied in the parity doublet models at zero or finite temperature [18–22]. We extend the parity doublet model by including ρ and ω mesons through the hidden local symmetry and also by adding a six-point interaction of a scalar meson. Here, as a first step, we will not consider hyperonic matter and work within the mean field approximation. We determine our model parameters, except the chiral invariant mass (m0), by performing global fitting to physical inputs (masses and pion decay constant in free space and nuclear matter properties). We then study the equation of state and the phase diagram of dense matter at finite temperature. We find that the predicted slope parameter at the saturation density meets the constraint from heavy ion experiments and neutron star observations (see, e.g. Refs. [23, 24]) and observe that the chiral condensate drops at the chiral and liquid-gas transition points. It is also seen that smaller m0 values prefer smaller critical densities for chiral phase transition. The study of asymmetric matter reveals that the first order nature of the liquid-gas transition disappears in asymmetric matter and the critical densities for the chiral transition become smaller with increasing asymmetries, which are consistent with previous studies. In section II we extend the parity doublet model, and in section III we fix the model parameters. Our results on bulk properties of nuclear matter and density dependence of chiral condensate and nucleon mass are given in section IV. We present the phase diagram of dense (asymmetric) matter in section V. Finally, conclusion and discussion follow in section VI

63 citations

Journal ArticleDOI
TL;DR: In this article, the low-energy interactions of these particles are governed by chiral effective theory, and operator coefficients are determined by fitting to zero temperature few-body scattering data.
Abstract: We study nuclear and neutron matter by combining chiral effective field theory with nonperturbative lattice methods. In our approach, nucleons and pions are treated as point particles on a lattice. This allows us to probe larger volumes, lower temperatures, and greater nuclear densities than in lattice QCD. The low-energy interactions of these particles are governed by chiral effective theory, and operator coefficients are determined by fitting to zero temperature few-body scattering data. The leading dependence on the lattice spacing can be understood from the renormalization group and absorbed by renormalizing operator coefficients. In this way, we have a realistic simulation of many-body nuclear phenomena with no free parameters, a systematic expansion, and a clear theoretical connection to QCD. We present results for hot neutron matter at temperatures 20-40 MeV and densities below twice the nuclear matter density.

63 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that the weak production of a pion and its subsequent scattering off nucleons leads to effective nuclear renormalizations of the axial current form factors.

63 citations

Journal ArticleDOI
TL;DR: In this paper, a universal effective NN interaction of the Skyrme type has been proposed which is suitable for both ground and excited states in nuclei throughout the nuclear mass table.

63 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023132
2022299
2021252
2020268
2019256
2018240