Isospin Asymmetric Nuclear Matter Research Articles

Low Density Neutron Star Matter with Quantum Molecular Dynamics: The Role of Isovector Interactions

The effect of isospin-dependent nuclear forces on the inner crust of neutron stars is modeled within the framework of Quantum Molecular Dynamics (QMD). To successfully control the density dependence of the symmetry energy of neutron-star matter below nuclear saturation density, a mixed vector-isovector potential is introduced. This approach is inspired by the baryon density and isospin density-dependent repulsive Skyrme force of asymmetric nuclear matter. In isospin-asymmetric nuclear matter, the system shows nucleation, as nucleons are arranged into shapes resembling nuclear pasta. The dependence of clusterization in the system on the isospin properties is also explored by calculating two-point correlation functions. We show that, as compared to previous results that did not involve such mixed interaction terms, the energy symmetry slope L is successfully controlled by varying the corresponding coupling strength. Nevertheless, the effect of changing the slope of the nuclear symmetry energy L on the crust-core transition density does not seem significant. To the knowledge of the authors, this is the first implementation of such a coupling in a QMD model for isospin asymmetric matter, which is relevant to the inner crust of neutron and proto-neutron stars.

Investigating effects of relativistic kinematics, dimensionality, interactions, and short-range correlations on the ratio of quartic over quadratic nuclear symmetry energies

While ample evidence for the so-called empirical parabolic law of the equation of state (EOS) of isospin asymmetric nuclear matter (ANM) has been obtained in many studies within both nonrelativistic and relativistic nuclear many-body theories using various interactions, it has been unclear if there is any fundamental physics reason for the small quartic symmetry energy compared to the quadratic one even as the ANM approaches pure neutron matter. Within both relativistic and nonrelativistic free Fermi gas (FFG) models in coordinate spaces of arbitrary dimension $d$ with and without considering short-range correlations (SRCs) as well as nonlinear relativistic mean field models, we study effects of relativistic kinematics, dimensionality, interactions, and SRC on the ratio $\mathrm{\ensuremath{\Psi}}(\ensuremath{\rho})$ of quartic over quadratic symmetry energies in ANM EOSs. We found that the ratio $\mathrm{\ensuremath{\Psi}}(\ensuremath{\rho})$ in the FFG model depends strongly on the dimension $d$. While it is very small already in the normal three-dimensional space, it could be even smaller in spaces with reduced dimensions for subsystems of particles in heavy-ion reactions and/or whole neutron stars due to constraints, collectivities, and/or symmetries. We also found that the ratio $\mathrm{\ensuremath{\Psi}}(\ensuremath{\rho})$ could theoretically become very large only at the ultrarelativistic limit far above the density reachable in neutron stars. However, nuclear interaction directly and/or indirectly through SRC-induced high-momentum nucleons affects significantly the density dependence of $\mathrm{\ensuremath{\Psi}}(\ensuremath{\rho})$ compared to the relativistic FFG model prediction. The SRCs affect significantly not only the kinetic energy of symmetric nuclear matter but also the ratio $\mathrm{\ensuremath{\Psi}}(\ensuremath{\rho})$ while the relativistic corrections are found negligible. Although we found no fundamental physics reason for the $\mathrm{\ensuremath{\Psi}}(\ensuremath{\rho})$ to be very small especially at high densities, the results may help better understand the EOS of dense neutron-rich matter.

Asymmetric Nuclear Matter in Relativistic Mean-field Models with Isoscalar- and Isovector-meson Mixing

Using the relativistic mean-field model with nonlinear couplings between the isoscalar and isovector mesons, we study the properties of isospin-asymmetric nuclear matter. Not only the vector mixing, ω μ ω μ ρ ν ρ ν , but also the quartic interaction due to the scalar mesons, σ 2 δ 2, is taken into account to investigate the density dependence of nuclear symmetry energy, E sym, and the neutron star properties. It is found that the δ meson increases E sym at high densities, whereas the σ–δ mixing makes E sym soft above the saturation density. Furthermore, the δ meson and its mixing have a large influence on the radius and tidal deformability of a neutron star. In particular, the σ–δ mixing reduces the neutron star radius; thus, the present calculation can simultaneously reproduce the dimensionless tidal deformabilities of a canonical 1.4 M ⊙ neutron star observed from the binary neutron star merger GW170817 and the compact binary coalescence GW190814.

Basic quantities of the equation of state in isospin asymmetric nuclear matter

Based on the Hugenholtz–Van Hove theorem, six basic quantities of the EoS in isospin asymmetric nuclear matter are expressed in terms of the nucleon kinetic energy t(k), the isospin symmetric and asymmetric parts of the single-nucleon potentials \(U_0(\rho ,k)\) and \(U_{\text {sym},i}(\rho ,k)\). The six basic quantities include the quadratic symmetry energy \(E_{\text {sym,2}}(\rho )\), the quartic symmetry energy \(E_{\text {sym,4}}(\rho )\), their corresponding density slopes \(L_2(\rho )\) and \(L_4(\rho )\), and the incompressibility coefficients \(K_2(\rho )\) and \(K_4(\rho )\). By using four types of well-known effective nucleon–nucleon interaction models, namely the BGBD, MDI, Skyrme, and Gogny forces, the density- and isospin-dependent properties of these basic quantities are systematically calculated and their values at the saturation density \(\rho _0\) are explicitly given. The contributions to these quantities from t(k), \(U_0(\rho ,k)\), and \(U_{\text {sym},i}(\rho ,k)\) are also analyzed at the normal nuclear density \(\rho _0\). It is clearly shown that the first-order asymmetric term \(U_{\text {sym,1}}(\rho ,k)\) (also known as the symmetry potential in the Lane potential) plays a vital role in determining the density dependence of the quadratic symmetry energy \(E_{\text {sym,2}}(\rho )\). It is also shown that the contributions from the high-order asymmetric parts of the single-nucleon potentials (\(U_{\text {sym},i}(\rho ,k)\) with \(i>1\)) cannot be neglected in the calculations of the other five basic quantities. Moreover, by analyzing the properties of asymmetric nuclear matter at the exact saturation density \(\rho _{\text {sat}}(\delta )\), the corresponding quadratic incompressibility coefficient is found to have a simple empirical relation \(K_{\text {sat,2}}=K_{2}(\rho _0)-4.14 L_2(\rho _0)\).

Density dependence of the quark condensate in isospin-asymmetric nuclear matter

We compute the density dependence of the quark condensate and how it changes under the influence of isospin-asymmetric nuclear matter. This is achieved by the calculation of the relevant Feynman diagrams using in-medium chiral perturbation theory. We find that the absolute value of the quark condensate decreases in nuclear matter by around $35%$ at normal nuclear density, in agreement with previous model-independent calculations. We also present an quantitative estimation of the difference of up- and down-quark in-medium condensates.

Thermal effects in hot and dilute homogeneous asymmetric nuclear matter

We present a comprehensive analysis of hot and dilute isospin-asymmetric nuclear matter employing the temperature-dependent effective-relativistic mean-field theory (E-RMF). The E-RMF is applied to study the effect of $\delta$ and $\omega-\rho$ meson cross-coupling on the thermal properties of asymmetric nuclear matter using two recently developed IOPB-I and G3 parameter sets. These sets are known to reproduce the nuclear matter properties in agreement with various experimental and observational constraints. We consider the nuclear matter to be homogeneous and study the equation of state (EoS) for densities, temperature and asymmetry which are relevant for astrophysical simulations such as supernovae explosion. The effect of temperature is investigated in reference to the density-dependent free symmetry energy and its higher-order derivatives using the well known parabolic approximation. The larger value of $\lambda_\omega$ cross-coupling in G3 in addition to the $\delta$ meson coupling in G3 smoothen the free symmetry energy. Thermal effects on various state variables are examined at fixed temperature and isospin asymmetry by separating their T=0 and the finite-T expressions. The thermal effects are mainly governed by effective mass with larger effective mass estimating larger thermal contribution. The effect of temperature on isothermal and isentropic incompressibility is discussed which is in harmony with various available microscopic calculations. The liquid-gas phase transition properties are examined in asymmetric matter with two conserved charges in the context of different slope parameter and comparable symmetry energy in IOPB-I and G3 set. The spinodal instability, binodal curve and critical properties are found to be influenced by the slope parameter $L_{sym}$.

Coexistence of isospin I = 0 and I = 1 pairings in asymmetric nuclear matter * *Supported by National Natural Science Foundation of China (11975282, 11775276, 11435014, 11505241), the Strategic Priority Research Program of Chinese Academy of Sciences (XDB34000000), the Youth Innovation Promotion Association of Chinese Academy of Sciences (Y2021414, Y201871)

The coexistence of neutron-neutron (n-n), proton-proton (p-p), and neutron-proton (n-p) pairings is investigated by adopting an effective density-dependent contact pairing potential. These three types of pairings can coexist only if the n-p pairing is stronger than the n-n and p-p pairings for the isospin asymmetric nuclear matter. In addition, the existence of n-n and p-p pairs might enhance n-p pairings in asymmetric nuclear matter when the n-p pairing strength is significantly stronger than the n-n and p-p ones. Conversely, the n-p pairing is reduced by the n-n and p-p pairs when the n-p pairing interaction approaches n-n and p-p pairings.

Progress on internal gas-jet target nuclear reaction at the HIRFL-CSR

Direct nuclear reactions induced by light ions, e.g., proton and alpha particles, have been investigated for about a century since the Geiger-Marsden experiment in 1908. It provides important information on nuclear structure and nuclear astrophysics. For instance, neutron skin thicknesses of nuclei determined by using proton and α elastic scattering play an important role in constraining the equation of state (EOS) of isospin asymmetric nuclear matter. These reactions were mostly conducted in direct kinematics, that is to say, the light-ion beam from accelerator interacts with a target made of the nuclei of interest. Obviously, such kinds of experimental investigations are limited to stable solid isotopes without active chemical property and radioactivity, due to the difficulty to make unstable targets. To test theoretical models developed from stable nuclei and explore new physical phenomenon on exotic nuclei, it is essential to investigate direct reactions on nuclei far from stability. As a result, experimental method based on inverse kinematics, namely active gas target technique, has been developed, where the unstable nuclei of interest produced by radioactive ion beam facilities collide with hydrogen and helium gases in a bubble chamber. The direct reactions are performed in inverse kinematics. One advantage is that low energy recoils at small center of mass angles can be measured easily at relatively large laboratory angles. However, this experimental method is insensitive to detect scattering recoils with energies of a few hundred keV, due to measurement based on gas detector. In recent years, a novel experimental method, namely study with stored beam in storage ring interacting with internal gas-jet target, has attracted much interest. It was proposed firstly for the exotic nuclei studied with light-ion induced reactions in storage rings (EXL) project. The technique is based on the internal gas-jet target instead of active gas target. It is an important supplementary experiential method for studying direct nuclear reactions induced by light ions, which is characterized by low-momentum sensitivity, high detection efficiency and low background. It is an ideal tool to study the isotopes with active chemical property and radioactivity. The cooler storage ring at the heavy ion research facility in Lanzhou (HIRFL-CSR) consists of a main cooler storage ring (CSRm) and an experimental cooler storage ring (CSRe). The two rings are connected by a radioactive ion beam line 2 (RIBLL2). The CSRe is equipped with an internal gas-jet target. As one of the existing facilities, the HIRFL-CSR provides an opportunity for performing in-ring direct nuclear reactions induced by light ions with the internal gas-jet target. Since 2016, a silicon strip detector compatibility with ultra-high vacuum in heavy-ion storage ring has been developed to build the in-ring direct nuclear reaction spectrometry at the HIRFL-CSR. A feasibility experiment on proton elastic scattering on 58Ni nuclei has been operated successfully by using the in-ring nuclear reaction spectrometry at the HIRFL-CSR. The nuclear matter distribution radius of 58Ni was extracted from measured differential cross sections at low momentum transfer. Proton elastic scattering experiment on 78Kr nuclei was also carried out to extract the nuclear matter radius at the beginning of 2021. In this paper, we report the development of in-ring direct nuclear reaction spectrometry at the HIRFL-CSR and corresponding experiments. Research plans in the (near) future, especially for measuring nuclear matter distribution radius of 133Cs, are also introduced.

In-medium pion dispersion relation and medium correction of near the threshold energy of pion production * *Supported by National Key R&D Program of China (2018 YFA0404404) and National Natural Science Foundation of China (11875323, 11875125, 11475262, 11961141003, 11790323, 11790324, 11790325) and the Continuous Basic Scientific Research Project (WDJC-2019-13,No BJ20002501)

Transport models cannot simultaneously explain very recent data on pion multiplicities and pion charged ratios from central collision of Sn+Sn at 0.27 A GeV. This stimulates further investigations on the pion dispersion relation, in-medium cross sections, and decay widths near the threshold energy or at subthreshold energy of pion production in isospin asymmetric nuclear matter. In this study, the pion dispersion relation, in-medium cross section, and decay width near the threshold energy are investigated in isospin asymmetric nuclear matter by using the one-boson-exchange model. With the consideration of the energy conservation effect, the in-medium cross sections are enhanced at GeV in a nuclear medium. The prediction of pion multiplicity and ratios near the threshold energy could be modified if this effect is considered in transport model simulations.

Constraints on Nuclear Saturation Properties from Terrestrial Experiments and Astrophysical Observations of Neutron Stars

Abstract Taking into account the terrestrial experiments and the recent astrophysical observations of neutron stars and gravitational-wave signals, we impose restrictions on the equation of state (EoS) for isospin-asymmetric nuclear matter. Using the relativistic mean-field model with SU(3) flavor symmetry, we investigate the impacts of effective nucleon mass, nuclear incompressibility, and slope parameter of nuclear symmetry energy on the nuclear and neutron star properties. It is found that the astrophysical information of massive neutron stars and tidal deformabilities, as well as the nuclear experimental data, plays an important role to restrict the EoS for neutron stars. In particular, the softness of the nuclear EoS due to the existence of hyperons in the core gives stringent constraints on those physical quantities. Furthermore, it is possible to put limits on the curvature parameter of nuclear symmetry energy by means of nuclear and astrophysical calculations.

Saturation properties of hot asymmetric nuclear matter using M3Y effective nucleon-nucleon interaction

Understanding the nuclear equation of state (EOS) is important for a broad range of applications ranging from nuclear structure to nuclear astrophysics. In this paper we apply a non-relativistic Hartree-Fock scheme to study the temperature dependence of the EOS of hot isospin-asymmetric nuclear matter (ANM), based on M3Y-type semi-realistic nucleon-nucleon interactions. We focus on the temperature dependence of the nuclear and thermodynamic properties of hot ANM at its equilibrium saturation point. The results show that increasing the temperature of the hot ANM decreases its saturation binding energy, shifting it to a higher saturation density, and increases its attractive saturation free energy, shifting it to a lower density. This makes the hotter ANM the less bound. Increasing the isospin-asymmetry of the ANM decreases both the saturation binding- and free-energy, and their corresponding densities. The binding (free energy) saturation point disappears at the temperatures larger than 17 MeV (14 MeV). The influence of temperature on the saturation binding and free energy increases with increasing T, but it remains almost steady with increasing the isospin-asymmetry. A maximum isospin-asymmetry Imax=0.81±0.02 is indicated for a semi-cold bound ANM having saturated free energy.

η mesons in hot and dense asymmetric nuclear matter

We study the $\eta N$ interactions in the hot and dense isospin asymmetric nuclear matter using two different approaches. In the first approach, the in-medium mass and optical potential of $\eta$-meson have been calculated in the chiral SU(3) model, considering the effect of explicit symmetry breaking term and range terms in the $\eta N$ interaction Lagrangian density. In the second scenario, the conjunction of chiral perturbation theory and chiral SU(3) model is employed. In this case, the next-to-leading order $\eta N$ interactions are evaluated from the chiral perturbation theory (ChPT), and the in-medium contribution of scalar densities are taken as input from chiral SU(3) model. We observe a larger negative mass-shift in the ChPT+chiral model approach compared to the chiral SU(3) model alone as a function of nuclear density. Moreover, the increase in the asymmetry and temperature cause a decrease in the magnitude of mass-shift. We have also studied the impact of $\eta N$ scattering length $a^{\eta N}$ on the $\eta$ meson mass $m^*_\eta$ and observed that the $m^*_\eta$ decrease more for increasing the value of scattering length.

Proton and neutron skins and symmetry energy of mirror nuclei

The neutron skin of nuclei is an important fundamental property, but its accurate measurement faces many challenges. Inspired by charge symmetry of nuclear forces, the neutron skin of a neutron-rich nucleus is related to the difference between the charge radii of the corresponding mirror nuclei. We investigate this relation within the framework of the Hartree-Fock-Bogoliubov method with Skyrme interactions. Predictions for proton skins are also made for several mirror pairs in the middle mass range. For the first time the correlation between the thickness of the neutron skin and the characteristics related with the density dependence of the nuclear symmetry energy is investigated simultaneously for nuclei and their corresponding mirror partners. As an example, the Ni isotopic chain with mass number A=48−60 is considered. These quantities are calculated within the coherent density fluctuation model using Brueckner and Skyrme energy-density functionals for isospin asymmetric nuclear matter with two Skyrme-type effective interactions, SkM* and SLy4. Results are also presented for the symmetry energy as a function of A for a family of mirror pairs from selected chains of nuclei with Z=20, N=14, and N=50. The evolution curves show a similar behavior crossing at the N=Z nucleus in each chain and a smooth growing deviation when N≠Z starts. Comparison of our results for the radii and skins with those from the calculations based on high-precision chiral forces is made.

Effects of density-dependent scenarios of in-medium nucleon-nucleon interactions in heavy-ion collisions

Using a more reasonable separate density-dependent scenario instead of the total density-dependent scenario for in-medium $nn$, $pp$ and $np$ interactions, we examine effects of differences of in-medium nucleon-nucleon interactions in two density-dependent scenarios on isospin-sensitive observables in central $^{197}$Au+$^{197}$Au collisions at 400 MeV/nucleon. Moreover, to more physically detect the differences between the nucleon-nucleon interactions in two density-dependent scenarios, we also map the nucleon-nucleon interaction in the separate density-dependent scenario into that in the total density-dependent scenario through fitting the identical constraints for symmetric nuclear matter as well as the identical slope parameter of nuclear symmetry energy at the saturation density. It is shown that two density-dependent scenarios also lead to essentially different symmetry potentials especially at high densities although they can lead to the identical equation of state for the symmetry nuclear matter as well as the identical symmetry energy for the isospin asymmetric nuclear matter. Consequently, these isospin-sensitive observables are also appreciably affected by the different density-dependent scenarios of in-medium nucleon-nucleon interactions. Therefore, according to these findings, it is suggested that effects of the separate density-dependent scenario of in-medium nucleon-nucleon interactions should be taken into account when probing the high-density symmetry energy using these isospin-sensitive observables in heavy-ion collisions.

Examination of an isospin-dependent single-nucleon momentum distribution for isospin-asymmetric nuclear matter in heavy-ion collisions

Within a transport model using nucleon momentum profiles as the input from a parameterized isospin-dependent single-nucleon momentum distribution, with a high momentum tail induced by short-range correlations, we employ \(^{197}\)Au + \(^{197}\)Au collisions at 400 MeV/nucleon to examine the effects of the short-range correlations on the pion and flow observables in probing the nuclear symmetry energy. We investigate how reliable this isospin-dependent single-nucleon momentum distribution is and determine the corresponding parameter settings. Apart from the significant effects of the short-range correlations on the pion and flow observables that are observed, we also find that the theoretical simulations of the \(^{197}\)Au + \(^{197}\)Au collisions with this momentum distribution using two sets of parameters, extracted from the experimental analysis and the self-consistent Green’s function prediction, can reproduce the neutron elliptic flows of the FOPI-LAND experiment and the \(\pi ^-/\pi ^+\) ratios of the FOPI experiment, respectively, under the symmetry energy setting in a particular range. Therefore, we conclude that this parameterized isospin-dependent single-nucleon momentum distribution is reliable for isospin-asymmetric nuclear matter. Correspondingly, two sets of parameters extracted from both the experimental analysis and the self-consistent Green’s function prediction cannot be excluded according to the available experimental information at present.

Density Dependence of Nuclear Matter Symmetry Energy: VMC Calculations

A Variational Monte-Carlo (VMC) method is employed to investigate the density dependence of the symmetry energy of isospin asymmetric nuclear matter. The realistic Urbana $$V$$ 14 nucleon–nucleon interaction potential of Lagaris and Pandharipande was used in the VMC calculations with addition of a phenomenological density-dependent term to simulate many-body interactions. The symmetry energy is obtained for different densities and compared with the data found in the literature, and it was observed that the results obtained in this study reasonably agree with the results found in the literature, and the symmetry energy is found to increase almost linearly with the density. We obtained the symmetry energy coefficient at saturation density $$\rho=0.16$$ fm $${}^{-3}$$ to be about 26.89 MeV, which is in agreement with the empirical value 30 $$\pm$$ 4 MeV. Also, the incompressibility factor of the nuclear matter and the equation of the state of pure neutron matter were reported. The results obtained are consistent with those obtained by various authors with different potentials and techniques.

The effect of the three-body force on the β-stable matter in RLOCV framework

The symmetry energy of isospin asymmetric nuclear matter (IANM), the density dependence of symmetry energy and also the equation of state (EOS) of the β-stable matter (BSM) are considered within relativistic corrections in the lowest order constrained variation approach (RLOCV) by using AV18 potential, with and without including Urbana (UIX) three-body force (TBF). The relative proton abundance for a wide range of baryon number density is calculated by including TBF in RLOCV approach. It is observed that if the bare two-body force (2BF) interaction AV18 is used, the relative proton abundance (ρp/ρB) increases by increasing baryon number density which tends to be saturated at high densities in both relativistic and non-relativistic treatments, while including TBF to our potential produces the ρp/ρB with higher values at low densities, which is saturated at the moderate densities in both LOCV and RLOCV frameworks. Moreover, adding the relativistic corrections (RC) to the results of β-stable matter decreases the value of proton abundance. In contrast, including TBF increases the value of ρp/ρB at low baryonic densities, which is saturated at the moderate baryon number densities. The opposite behaviors are also found on the saturation properties of nuclear matter by including TBF and RC to our calculations. It is also shown that the effect of TBF is much larger than that of the RC. Our results agree with other interactions and methods.

Properties of the nuclear symmetry energy studied by the radioactivity of unstable nuclei

In this paper, the properties of the symmetry energy in asymmetric nuclear matter, including the quadratic and quartic symmetry energies as well as their density slopes at the saturation density, are studied by the radioactivity of unstable nuclei. The symmetry energy was initially introduced as a quantum correction energy in the Weizsacker-Bethe liquid-drop model, which was proposed to describe the binding energies of finite nuclei. In order to systematically study the properties of the symmetry energy, the concept of the nuclear matter was introduced, which consists of neutrons and protons with finite neutron and proton densities but infinite neutron and proton numbers. By comparing the properties of the isospin symmetric nuclear matter, in which the neutron density is equal to the proton density, and those of the isospin asymmetric nuclear matter, in which the two densities are unequal, the symmetry energy is found to approximately represent the difference of the energy per nucleon in them. That is to say, the symmetry energy is an evaluation of the energy cost to convert protons in symmetric nuclear matter to neutrons in asymmetric nuclear matter. Since the symmetry energy characterizes the isospin asymmetric effect in nuclear matter, it plays critical roles in not only nuclear physics but also astrophysics. For example, the symmetry energy is closely related to the nuclear masses, the structures and properties of nuclei far away from stability line and near drip lines, the mechanism of heavy-ion reactions, the structures and component of neutron stars, the masses and radii of neutron stars, the cooling process of neutron stars, and so on. Besides of the quadratic symmetry energy, the quartic symmetry energy can have obvious effects on the properties of neutron stars as well. The quartic symmetry energy can significantly affect both the proton fraction in β-stable neutron stars and the critical density for the direct Urca process, which leads to faster cooling of neutron stars. In addition, the quartic symmetry energy is found to be very important for the location of the inner edge of crusts and the core-crust transition density and pressure in neutron stars. So the quartic symmetry energy can also have an influence on the structure of neutron stars. Because of the very important roles of the symmetry energy playing in not only nuclear physics but also astrophysics, it is of great significance to study the properties of both the quadratic and quartic symmetry energies. Based on the fundamental Hugenholtz-Van Hove (HVH) theorem, the properties of the symmetry energy are found to be closely related to the isoscalar and the isovector parts of the nucleon single-particle potentials, where the latter two parts can be extracted from the nuclear radioactivity. So by linking both the symmetry energy and the nuclear radioactivity to the nucleon single-particle potentials, the symmetry energy can be directly studied by nuclear radioactivity. In this paper, both the heavy-cluster radioactivity and the proton radioactivity are employed to constrain the properties of not only the quadratic symmetry energy but also the quartic symmetry energy. Besides, the effect of both the spectroscopic factor of proton radioactivity and the deformation in the daughter nucleus on the extracted results are also discussed, which are subsequently found to be very limited.

Charmonium decay widths in magnetized matter

We study the partial decay widths of the charmonium states ($J/\psi$, $\psi(3686)$, $\psi(3770)$, $\chi_{c0}$, $\chi_{c2}$) to $D\bar D$ ($D^+D^-$ or $D^0\bar {D^0}$) in isospin asymmetric nuclear matter, in the presence of strong magnetic fields. The in-medium partial decay widths of charmonium states to $D\bar D$ are calculated within a light quark--antiquark pair creation model, namely the $^3P_0$ model, using the in--medium masses of the charmonia as well as $D$ and $\bar D$ mesons in the magnetized nuclear matter obtained within a chiral effective model. The presence of a magnetic field leads to Landau quantization of the energy levels of the proton in the nuclear medium. The effects of magnetic field and isospin asymmetry on the charmonium decay widths to $D\bar D$ are found to be quite prominent. The effects of the anomalous magnetic moments have also been taken into consideration for obtaining the in-medium masses of these heavy flavour mesons, used to calculate the partial decay widths of the charmonium states. The medium modifications of the charmonium decay widths can have observable consequences on the production of the charmed mesons in high energy asymmetric heavy ion collision experiments.

Octet baryon masses and magnetic moments in hot and dense isospin asymmetric nuclear matter

Medium modification of the magnetic moments of octet baryons in the isospin asymmetric nuclear medium at finite temperature has been calculated using medium modified quark and baryon masses derived in chiral SU(3) quark mean field model. The magnetic moments of baryons are found to vary significantly as a function of density of nuclear medium as well as with the increase in isospin asymmetry of the medium. The rise of temperature is found to decrease the effect of isospin asymmetry on masses and magnetic moments of baryons. The results of present investigation may be helpful to understand the experimentally observed values of octet baryon magnetic moments at different experimental facilities.