Ilona Bednarek, Ryszard Manka
The extended nonlinear model has been applied to construct neutron star matter equation of state. In the case of neutron star matter with non-zero strangeness the extension of the vector meson sector by the inclusion of nonlinear mixed terms results in the stiffening of the equation of state and accordingly in the higher value of the maximum neutron star mass.
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We study the effects of isovector-scalar ($δ$)-meson on neutron star. Influence of $δ$-meson on both static and rotating neutron star is discussed. Inclusion of $δ$-meson in a neutron star system consisting of proton, neutron and electron, make the equation of state stiffer in higher density and consequently increases the maximum mass of the star. But induction of $δ$-meson in the hyperon star decreases the maximum mass of the hyperon star. This is due to the early evolution of hyperons in presence of $δ-$meson.
Nuclear effective interactions are considered as a vital tool to guide into the region of the high degree of isospin asymmetry and density. We take varieties of parameter sets of the RMF model to show the parametric dependence of the hyperon star properties. We add $ϕ_0$-meson to $σ$-$ω$-$ρ$ model. The effects of $ϕ_0$-meson on the equation of state and consequently on the maximum mass of the hyperon star are discussed. Due to the inclusion of $ϕ_0$-meson the threshold density of different hyperon production shift to higher density region. The effects of the hyperon-meson coupling constants on…
Strong pion and kaon couplings to hyperons are given in the bound-state approach to the Skyrme model.
We calculate the magnetic moments of hyperons in dense nuclear matter by using relativistic quark models. Hyperons are treated as MIT bags, and the interactions are considered to be mediated by the exchange of scalar and vector mesons which are approximated as mean fields. Model dependence is investigated by using the quark-meson coupling model and the modified quark-meson coupling model; in the former the bag constant is independent of density and in the latter it depends on density. Both models give us the magnitudes of the magnetic moments increasing with density for most octet baryons. But…
The effects of $ϕ$-meson on properties of hyperon stars are studied systematically in the framework of the density dependent relativistic mean field (DDRMF) model. The $ϕ$-meson shifts hyperon threshold to a higher density and reduces the hyperon fractions in neutron star cores. It also strongly stiffens the equation of state (EoS) calculated with various DDRMF effective interactions and increases the maximum mass of hyperon stars, but only a few effective interactions survive under the constraints from recent astrophysical observations. In the DDRMF model, the conformal limit of sound velocit…
We generalize the Bogoliubov quark-meson coupling model to also include hyperons. The hyperon-$σ$-meson couplings are fixed by the model and the hyperon-$ω$-meson couplings are fitted to the hypreon potentials in symmetric nuclear matter. The present model predicts neutron stars with masses above 2$M_\odot$ and the radius of a 1.4$M_\odot$ star equal to 13.83 km.
Excited negative parity hyperon masses are calculated in a chiral bag model in which the pion and the kaon fields are treated as perturbations. We also calculate the hadronic widths of $\lama$ and $\lamb$ as well as the coupling constants of the lightest $I=0$ excited hyperon to the meson-baryon channels, and discuss how the dispersive effects of the hadronic meson-baryon decay channels affect the excited hyperon masses. Meson cloud corrections to the electromagnetic decay widths of the two lightest excited hyperons into ground states $\lamz$ and $\sigz$ are calculated within the same model an…
The possibility of the appearance of $Δ$ isobars in neutron star matter and the so called {\it $Δ$ puzzle} is studied in a modified quark meson coupling model where the confining interaction for quarks inside a baryon is represented by a phenomenological average potential in an equally mixed scalar-vector harmonic form. The hadron-hadron interaction in nuclear matter is then realized by introducing additional quark couplings to $σ$, $ω$, and $ρ$ mesons through mean-field approximations. The couplings of the $Δ$ to the meson fields are fixed from available constraints while the hyperon coupling…
Hyperon-nucleon interactions are presented that are derived either in the conventional meson-exchange picture or within leading order chiral effective field theory. The chiral potential consists of one-pseudoscalar-meson exchanges and non-derivative four-baryon contact terms. With regard to meson-exchange hyperon-nucleon models we focus on the new potential of the Juelich group, whose most salient feature is that the contributions in the scalar--isoscalar (σ) and vector--isovector (ρ) exchange channels are constrained by a microscopic model of correlated ππand KKbar exchange.
We determine the equation of state (EOS) of nuclear matter with the inclusion of hyperons in a self-consistent manner by using a Modified Quark Meson Coupling Model (MQMC) where the confining interaction for quarks inside a baryon is represented by a phenomenological average potential in an equally mixed scalar-vector harmonic form. The hadron-hadron interaction in nuclear matter is then realized by introducing additional quark couplings to $σ$, $ω$, and $ρ$ mesons through mean-field approximations. The effect of a nonlinear $ω$-$ρ$ term on the equation of state is studied. The hyperon couplin…
We investigate the possibility and consequences of phase transitions from an equation of state (EOS) describing nucleons and hyperons interacting via mean fields of sigma, omega, and rho mesons in the recently improved quark-meson coupling (QMC) model to an EOS describing a Fermi gas of quarks in an MIT bag. The transition to a mixed phase of baryons and deconfined quarks, and subsequently to a pure deconfined quark phase, is described using the method of Glendenning. The overall EOS for the three phases is calculated for various scenarios and used to calculate stellar solutions using the Tolm…
The properties of neutron stars are investigated by including $δ$ meson field in the Lagrangian density of modified quark-meson coupling model. The $Σ^-$ population with $δ$ meson is larger than that without $δ$ meson at the beginning, but it becomes smaller than that without $δ$ meson as the appearance of $Ξ^-$. The $δ$ meson has opposite effects on hadronic matter with or without hyperons: it softens the EOSes of hadronic matter with hyperons, while it stiffens the EOSes of pure nucleonic matter. Furthermore, the leptons and the hyperons have the similar influence on $δ$ meson effects. The $…
Whether the massive neutron star PSR J0348+0432 can change into a hyperon star is studied in the framework of the relative mean field theory by choosing the suitable hyperon coupling constants. We find that whether the mesons $σ^{*}$ and $ϕ$ being considered or not, the neutron star PSR J0348+0432 all can change into a hyperon star and the hyperon star transition density are the same for the two cases. We also find that the canonical mass neutron star also can change into a hyperon star in a minor hyperon star transition density as the mesons $σ^{*}$ and $ϕ$ are not considered. Our results con…
SU(3), baryon octets and a meson cloud model are compared for the flavor asymmetry of sea quarks in the $Σ^+$, as an example. Large differences are found, especially between SU(3) and the meson cloud model. We suggest Drell-Yan measurements of $Σ^{+}-p$ and $Σ^{+}- d$ to test the prediction of various models. We use the meson cloud model to predict both valence and sea quark distributions.
Kaon-meson condensation and $Δ$ resonance in hyperonic stellar matter within a relativistic mean-field model
本文在含超子的IUFSU模型中引入$Δ$(1232)共振和Kaon凝聚，发现$Δ$共振的较早出现可将超子和Kaon临界密度推向高密度区并保证星体分支稳定，同时使物态方程在低密度区变软以符合GW170817观测，最终获得质量超过2倍太阳质量的中子星。
Relativistic mean-field theory with $δ$ meson, nonlinear isoscalar self-interactions and isoscalar-isovector cross interaction terms with parametrizations obtained to reproduce Dirac-Brueckner-Hartree-Fock calculations for nuclear matter is used to study asymmetric nuclear matter properties in $β$-equilibrium, including hyperon degrees of freedom and (hidden) strange mesons. Influence of cross interaction on composition of hyperon matter and electron chemical potential is examined. Softening of nuclear equation of state by the cross interactions results in lowering of hyperonization, although …
We discuss to which extent the modifications of the hyperon--scalar-meson coupling constants affect the equation of state (EoS) hypernuclear matter. The study is carried out within a relativistic density functional theory. The nucleonic matter is described in terms of a density-dependent parametrization of nucleon-meson couplings, whereas the hyperon--meson couplings are deduced from the octet model. We identify the parameter space of hyperon-meson couplings for which massive stellar configurations with $M\le 2.25 M_{\odot}$ exist. We also discuss the EoS at finite temperatures with and withou…
A one-boson-exchange model for the hyperon-nucleon (ΛN, ΣN) interaction is presented. The model incorporates the standard one boson exchanges of the lowest pseudoscalar and vector meson multiplets with coupling constants fixed by SU(6) flavor symmetry relations. As the main new feature of the model, the contributions in the scalar--isoscalar (σ) and vector--isovector (ρ) exchange channels are now constrained by a microscopic model of correlated ππand K \bar K exchange. Additional short-ranged ingredients of the model in the scalar--isovector (a_0) and scalar--isospin-1/2 (κ) channels are likew…
We study the effects of strong magnetic fields on the properties of hyperonic matter. We employ the relativistic mean field theory, which is known to provide excellent descriptions of nuclear matter and finite nuclei. The two additional hidden-strangeness mesons, $σ^{\ast}$ and $ϕ$, are taken into account, and some reasonable hyperon potentials are used to constrain the meson-hyperon couplings, which reflect the recent developments in hypernuclear physics. It is found that the effects of strong magnetic fields become significant only for magnetic field strength $B>5 \times 10^{18}$ G. The thre…
Density-dependent relativistic mean-field model for $ Ξ^{-} $ hypernuclei
本研究采用密度依赖的相对论平均场模型，通过拟合实验数据开发新的 $ΞN$ 有效相互作用，并研究密度依赖耦合及 $δ$ 介子对 $Ξ^{-}$ 超核单粒子性质的影响，强调介质效应和介子交换自由度的重要性。
We investigate compact star properties within the quark meson coupling model (QMC) with a soft symmetry energy density dependence at large densities. In particular, the hyperon content and the mass/radius curves for the families of stars obtained within the model are discussed. The hyperon-meson couplings are chosen according to experimental values of the hyperon nuclear matter potentials, and possible uncertainties are considered. It is shown that a softer symmetry energy gives rise to stars with less hyperons, smaller radii and larger masses. Hyperon-meson couplings may also have a strong ef…
The vacuum fluctuation (VF) effects on the properties of the hyperonic neutron star matter are investigated in the framework of the relativistic mean field (RMF) theory. The VF corrections result in the density dependence of in-medium baryon and meson masses. We compare our results obtained by adopting three kinds of meson-hyperon couplings. The introduction of both hyperons and VF corrections soften the equation of state (EoS) for the hyperonic neutron star matter and hence reduce hyperonic neutron star masses. The presence of the $δ$ field enlarges the masses and radii of hyperonic neutron s…
The recent measurement of the mass of neutron stars (PSR J1614 - 2230, PSR J0348 + 0432, MSP J0740 + 6620) restricts the lower limit $\sim 2M_{\odot}$ of the maximum mass of such compact stars, making it possible for dense matter to exist in massive stars. The relativistic mean field theory with parameter sets FSUGold including Kaon condensation is used to describe the properties of neutron stars in $β$ equilibrium. Through careful choice of the parameter of the $σ$-cut $c_σ$, we are able to produce a maximum mass neutron star with Kaon condensation heavier than $2M_{\odot}$, and we find that …
The measured electromagnetic form factors of $Λ$ hyperon in the time-like region are significantly deviated from pQCD prediction. We attribute the non-vanishing cross section near threshold to be the contribution of below-threshold $ϕ$(2170) state, supporting its exotic structure. Above the threshold, we find significant role of a wide vector meson with the mass of around 2.34 GeV, which would be the same state present in $p\bar{p}$ annihilation reactions. As a result, we give a satisfactory description of the behavior of existing data without modifying pQCD expectation.
We upgrade a SU_6 quark-model description for the nucleon-nucleon and hyperon-nucleon interactions by improving the effective meson-exchange potentials acting between quarks. For the scalar- and vector-meson exchanges, the momentum-dependent higher-order term is incorporated to reduce the attractive effect of the central interaction at higher energies. The single-particle potentials of the nucleon and Lambda, predicted by the G-matrix calculation, now have proper repulsive behavior in the momentum region q_1=5 - 20 fm^-1. A moderate contribution of the spin-orbit interaction from the scalar-me…
In this work we extend our formalism to study meson-baryon interactions by including $s$- and $u$-channel diagrams for pseudoscalar-baryon systems. We study the coupled systems with strangeness $-1$ and focus on studying the isospin-1 resonance(s), especially in the energy region around 1400 MeV. By constraining the model parameters to fit the cross section data available on several processes involving relevant channels, we find resonances in the isoscalar as well as the isovector sector in the energy region around 1400 MeV.
We propose a dynamical mechanism which provides an interaction between the spins of hyperons and antihyperons and the vorticity of the baryon current in noncentral high energy nuclear collisions. The interaction is mediated by massive vector and scalar bosons which is well known to describe the nuclear spin-orbit force. It follows from the Foldy-Wouthuysen transformation and leads to a strong-interaction Zeeman effect. The interaction may explain the difference in polarizations of $Λ$ and $\barΛ$ hyperons as measured by the STAR Collaboration at the BNL Relativistic Heavy Ion Collider. The sig…
In this paper the impact of the strength of hyperon-nucleon and hyperon-hyperon on the maximum neutron star mass is shown. The strong hyperon-hyperon coupling constant together with the additional nonlinear meson interaction terms lead to the essential softening of the equation of state and to the existence of another more compact branch of stable neutron star configurations. The analysis of the mass-radius relations leads to the conclusion that the additional stable configurations of hyperon-rich neutron stars are characterized by the reduced value of radii.
Since 2013 the mass of pulsar PSR J0348+0432 ($M = 2.01\,M_{\odot}$) has provided a tight constraint on neutron star equation of state. However, a number of different analyses of the recently detected BNS merger (GW170817) point to a maximum neutron star mass around $2.16\,M_{\odot}$. In addition, a recent study determined the mass of the millisecond pulsar PSR J2215+5135 to be $2.27^{+0.17}_{-0.15}\,M_{\odot}$. In this work we investigate the presence of hyperons in neutron star matter in light of these new mass measurements using equations of state calculated in the relativistic mean-field a…
Within a density-dependent relativistic mean-field model using in-medium meson-hadron coupling constants and meson masses, we explore effects of in-medium hyperon interactions on properties of neutron stars. It is found that the hyperonic constituents in large-mass neutron stars can not be simply ruled out, while the recently measured mass of the millisecond pulsar J1614-2230 can constrain significantly the in-medium hyperon interactions. Moreover, effects of nuclear symmetry energy on hyperonization in neutron stars are also discussed.
The in-medium behavior of bottom-strange pseudoscalar mesons in hot, isospin asymmetric and dense hadronic environment is studied using a chiral effective model. The same was recently generalized to the heavy quark sector and employed to study the behavior of open-charm and open-bottom mesons. The heavy quark (anti-quark) is treated as frozen and all medium modifications of these bottom-strange mesons are due to their strange anti-quark (quark) content. We observe a pronounced dependence of their medium mass on baryonic density and strangeness content of the medium. Certain aspects of these in…
The YN results are presented from the Extended-soft-core (ESC) interactions. They consist of local- and non-local-potentials due to (i) One-boson-exchange (OBE), with pseudoscalar-, vector-, scalar-, and axial-vector-nonets, (ii) Diffractive exchanges, (iii) Two-pseudoscalar exchange, and (iv) Meson-pair-exchange (MPE). This model, called ESC04, describes NN and YN in a unified way using broken flavor SU(3)-symmetry. Novel ingredients are the inclusion of (i) the axial-vector-mesons, (ii) a zero in the scalar- and axial-vector meson form factors. We describe simultaneous fits to the NN- and YN…
We predict the energy per baryon in nuclear matter with non-zero fraction of $Λ$ hyperons. We include Dirac effects on the nucleons as well as the $Λ$ and describe how the latter is implemented. We use the nucleon-hyperon meson-exchange potentials from the Juelich group, the latest as well as an earlier version. The dependence of the results on the many-body framework and on the nucleon-hyperon interaction model is discussed.
We extend the relativistic Hartree-Fock (RHF) theory to study the structure of single-$Λ$ hypernuclei. The density dependence is taken in both meson-nucleon and meson-hyperon coupling strengths, and the induced $Λ$-nucleon ($ΛN$) effective interactions are determined by fitting $Λ$ separation energies to the experimental data for several single-$Λ$ hypernuclei. The equilibrium of nuclear dynamics described by the RHF model in normal atomic nuclei, namely, the balance between nuclear attractive and repulsive interactions, is then found to be drastically changed in single-$Λ$ hypernuclei, reveal…
We study the equation of state of hyperon-rich matter for neutron stars using an extended relativistic mean-field model. We take special care of the recently proposed non-linear behaviour of the vector field which gives a much better description of Dirac-Brueckner calculations. The hyperon-hyperon interaction is also implemented by introducing additional meson exchanges. These new terms avoid the instability found at high densitites in previous works while keeping the excellent description for finite nuclear systems. We also demonstrate within the mean-field approach that the presence of hyper…
In this theoretical study, we report an investigation of the equations of state (EoSs) ofhyper-nuclear matter and its composition as a function of density within the framework of effective field theory motivated relativistic mean field model. We have used G2 force parameter along with various hyperon-meson coupling ratios by allowing the mixing and the breaking of SU(6) symmetry to predict the EoSs, keeping the nucleonic coupling constant intact. We have estimated the properties of non-rotating and rapidly rotating configuration of compact stars by employing four different representative sets …
Constraining hyperonic relativistic mean-field models with rapidly rotating neutron stars
本研究以PSR J0952−0607脉冲星的质量测量结果为依据，采用自旋-味SU(6)对称方案引入超子，通过计算旋转中子星构型，将该脉冲星的观测约束映射到RMF模型的参数空间，实现对超子RMF模型的约束。
In this work we introduce an extended version of the formalism proposed originally by Taurines et al. that considers the effects of many-body forces simulated by non-linear self-couplings and meson-meson interaction contributions. In this extended version of the model, we assume that matter is at zero temperature, charge neutral and in beta-equilibrium, considering that the baryon octet interacts by the exchange of scalar-isoscalar ($σ$,$\,σ^*$), vector-isoscalar ($ω$,$\,ϕ$), vector-isovector ($\varrho$) and scalar-isovector ($δ$) meson fields. Using nuclear matter properties, we constrain the…
We study the equation of state and composition of hypernuclear matter within a relativistic density functional theory with density-dependent couplings. The parameter space of hyperon--scalar-meson couplings is explored by allowing for mixing and breaking of SU(6) symmetry, while keeping the nucleonic couplings constant fixed. The subset of equations of state, which corresponds to small values of hyperon--scalar-meson couplings allows for massive M < 2.25 M_solar compact stars; the radii of hypernuclear stars are within the range 12--14 km. We also study the equation of state of hot neutrino-ri…
Effects of Phi and $σ^{*}$-meson on properties of hyperon stars including $Δ$ resonance
本研究利用线性相对论平均场理论，通过σ-cut方案并考虑超子和Δ共振，研究了奇异介子σ*和φ对中子星性质的影响，发现Δ共振抑制超子并减小中子星半径，有助于解决超子难题。
A systematic study of global spin polarizations and correlations of hadrons with different spins in relativistic heavy ion collisions
本文系统研究了重离子碰撞中不同自旋强子的自旋极化和相关性，包括向量介子、自旋1/2和3/2超子及强子-强子相关性，探讨了特殊案例的物理后果。
We develop a new equation of state (EoS) table involving thermal (anti)kaons, Bose-Einstein condensate of $K^{-}$ mesons and $Λ$-hyperons for core-collapse supernova and neutron star merger simulations. This EoS table is based on a finite temperature density-dependent relativistic hadron field theory where baryon-baryon interaction is mediated by scalar $σ$, vector $ω$ and $ρ$ mesons, using the parameter set DD2 for nucleons. The repulsive hyperon-hyperon interaction is mediated by an additional strange $ϕ$ meson. The EoS for the $K^-$ condensed matter is also calculated within the framework o…
Hyperon longitudinal polarization and vector meson spin alignment in a thermal model for heavy-ion collisions
研究通过热模型探讨重离子碰撞中超子纵向极化与矢量介子自旋对齐的共同机制，发现两者存在相关性，但模型尚无法完全定量解释数据。
Single-particle energies of the $Λ$ and $Σ$ hyperons are obtained from the relevant self-energies. The latter are constructed within the framework of a perturbative many-body approach employing present realistic hyperon-nucleon interactions such as the models of the Juelich and Nijmegen groups. The effects of the non-locality and energy dependence of the self-energy on the bound states are investi- gated. It is also shown that, although the single-particle hyperon energies are well reproduced by local Woods-Saxon hyperon-nucleus potentials, the wave functions from the non-local self-energy are…
We build upon the remarkable, model independent constraints on the equation of state of dense baryonic matter established recently by Annala et al. [1]. Using the quark-meson coupling model, an approach to nuclear structure based upon the self-consistent adjustment of hadron structure to the local meson fields, we show that, once hyperons are allowed to appear in dense matter in \b{eta}-equilibrium, the equation of state is consistent with those constraints. As a result, while one cannot rule out the occurence of quark matter in the cores of massive neutron stars, the available constraints are…
Chiral Lagrangian and quark-meson coupling models of hyperon matter are used to estimate the maximum mass of neutron stars. Our relativistic calculations include, for the first time, both Hartree and Fock contributions in a consistent manner. Being related to the underlying quark structure of baryons, these models are considered to be good candidates for describing the dense core of neutron stars. Taking account of the known experimental constraints at saturation density, the equations of state deduced from these relativistic approaches cannot sustain a neutron star with a mass larger than 1.6…
The constituents of cold dense matter are still far from being understood. However, neutron star observations such as the recently observed pulsar PSR J1614-2230 with a mass of 1.97+/-0.04 M_solar help to considerably constrain the hadronic equation of state (EoS). We systematically investigate the influence of the hyperon potentials on the stiffness of the EoS. We find that they have but little influence on the maximum mass compared to the inclusion of an additional vector meson mediating repulsive interaction amongst hyperons. The new mass limit can only be reached with this additional meson…
The density dependent relativistic hadron (DDRH) theory is introduced as an effective field theory for nuclei and hypernuclei. A Dirac-Brueckner approach to in-medium nucleon-hyperon interactions is presented. Density dependent meson-baryon vertices are determined from DBHF self-energies in infinite matter. Scaling laws for hyperon vertices are derived from a diagrammatic analysis of self-energies. In a local density approximation the DB vertices are applied in relativistic DDRH Hartree calculations to finite hypernuclei. Lambda single particle spectra and spin-orbit splittings are described r…
The neutron star as a supernova remnant is attracting high attention recently due to the gravitation wave detection and precise measurements about its mass and radius. In the inner core region of the neutron star, the strangeness degrees of freedom, such as the hyperons, can be present, which is also named as a hyperonic star. In this work, the neutron star consisting of nucleons and leptons, and the hyperonic star including the hyperons will be reviewed in the framework of the relativistic mean-field (RMF) model. The popular non-linear and density-dependent RMF parametrizations in the market …
The pieces of the hypernuclear strangeness violating potential due to the pseudoscalar meson exchanges are derived using methods which were successfully applied to hyperon nonleptonic decays. The estimates are tested by comparison with measured hyperon nonleptonic decay amplitudes. All isospin changes $ΔI=1/2$ and $ΔI=3/2$ are included in the derived potential. All calculational methods used are reviewed and described in detail.
We have constructed the leading order hyperon-nucleon potential in a chiral Effective Field Theory approach. The chiral potential consists of one-pseudoscalar-meson exchanges and non-derivative four-baryon contact terms. The hyperon-nucleon interactions are derived using SU(3) symmetry, the nucleon-nucleon interaction is not considered explicitly since it can not be described well with a leading order chiral Effective Field Theory. We solve a regularized Lippmann-Schwinger equation and show that a good description of the available hyperon-nucleon scattering data is possible with five free para…
With the discovery of massive neutron stars such as PSR J1614-2230, the question has arisen whether exotic matter such as hyperons can exist in the neutron star core. We examine the conditions under which hyperons can exist in massive neutron stars. We consistently investigate the vector meson-hyperon coupling, going from SU(6) quark model to a broader SU(3) symmetry. We propose that the maximum neutron star mass decreases linearly with the strangeness content f_s of the neutron star core as M_max(f_s) = M_max(0) - 0.6 M_solar (f_s/0.1), which seems to be independent of the underlying nuclear …
Possible coexistence of kaon condensation and hyperons in highly dense matter [the ($Y+K$) phase] is investigated on the basis of the relativistic mean-field theory combined with the effective chiral Lagrangian. Two coupling schemes for the $s$-wave kaon-baryon interaction are compared regarding the onset density of kaon condensation in the hyperon-mixed matter and equation of state for the developed ($Y+K$) phase: One is the contact interaction scheme related to the nonlinear effective chiral Lagrangian. The other is the meson-exchange scheme, where the interaction vertices between the kaon f…
In this talk we report on how, using a chiral unitary approach for the meson--baryon interactions, two octets of $J^π=1/2^-$ baryon states and a singlet are generated dynamically, resulting in the case of strangeness $S=-1$ in two poles of the scattering matrix close to the nominal $Λ(1405)$ resonance. We suggest experiments which could show evidence for the existence of these states.
In this talk I review the findings of our recent works where we have studied the decay of $N^*(1895)$ and the implications of such properties on the photoproduction of light hyperons. I discuss that meson-baryon interactions play an essential role in describing the nature of $N^*(1895)$ and report the details of our investigation of its decays to different meson-baryon systems and to final states involving $Λ(1405)$ and a proposed $Σ(1400)$. We find that the width of $N^*(1895)$ gets important contributions from the decay to light hyperon resonances. Such an information can be used to look for…
We study the $^1S_0$ superfluidity of $Λ$ hyperons in neutron star matter and neutron stars. We use the relativistic mean field (RMF) theory to calculate the properties of neutron star matter. In the RMF approach, the meson-hyperon couplings are constrained by reasonable hyperon potentials that include the updated information from recent developments in hypernuclear physics. To examine the $^1S_0$ pairing gap of $Λ$ hyperons, we employ several $ΛΛ$ interactions based on the Nijmegen models and used in double-$Λ$ hypernuclei studies. It is found that the maximal pairing gap obtained is a few te…
An analytic parametrization of the hyperonic matter equation of state based on microscopic Brueckner-Hartree-Fock calculations has been constructed using the realistic Argonne V18 nucleon-nucleon potential plus a three-body force of Urbana type, and three models of the hyperon-nucleon interaction: the Nijmegen soft-core models NSC89 and NSC97e, and the most recent meson-exchange potential of the Juelich group. The construction of this parametrization is based on a simple phase-space analysis and reproduces with good accuracy the results of the microscopic calculations with a small number of pa…
We calculate hyperon-nucleon and hyperon-hyperon interactions at next-to-leading order in SU(3) baryon chiral perturbation theory extending earlier work by the Bonn-Juelich group. The constructed potentials in momentum space include all one- and two-meson exchange terms generated by the SU(3) chiral Lagrangian. Effects from intermediate decuplet baryons are considered as well. These chiral baryon-baryon potentials, together with appropriate contact terms, provide a new basis for systematic studies of hyperon-nucleon scattering and light hypernuclei.
In this proceeding we summarize results for baryonic contact terms derived within SU(3) chiral effective field theory. The four-baryon contact terms, necessary for the description of the hyperon-nucleon interaction, include SU(3) symmetric and explicit chiral symmetry breaking terms. They also include four-baryon contact terms involving pseudoscalar mesons, which become important for three-body forces. Furthermore we derive the leading order six-baryon contact terms in the non-relativistic limit and study their contribution to the $ΛNN$ three-body contact interaction. These results could play …
Systematic study of scalar, vector, and mixed density dependencies in relativistic mean-field descriptions of hyperonic matter in neutron stars
本文在DDRMF框架内研究中子星超子物质EOS，系统考察介子-重子耦合的标量、矢量及混合密度依赖性，发现新参数化产生更硬EOS，引入Λ超子后变软但仍满足两倍太阳质量限制且符合NICER观测。
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