Neutron stars with large masses ∼ 2M ⊙ require the hard stiffness of equation of state (EoS) of neutron-star matter. On the other hand, hyperon mixing brings about remarkable softening of EoS. In order to solve this "Hyperon puzzle in neutron stars", a multi-pomeron exchange potential (MPP) is introduced as a model for the universal many-body repulsion in baryonic systems on the basis of the Extended Soft Core (ESC) baryon-baryon interaction. The strength of MPP is determined by analyzing the nucleus-nucleus scattering with the G-matrix folding model. The interactions in ΛN, ΣN and ΞN channels are shown to be consistent with experimental indications. The EoS in neutron-star matter with hyperon mixing is obtained from ESC in addition of MPP, and mass-radius relations of neutron stars are derived. The maximum mass is shown to reach 2M ⊙ even in the case of including hyperon mixing by model-parameters determined by terrestrial experiments.

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We investigate the possibilities of using measurements in present and future experiments on heavy ion collisions to answer some longstanding problems in hadronic physics, namely identifying hadronic molecular states and exotic hadrons with multiquark components. The yields of a selected set of exotic hadron candidates in relativistic heavy ion collisions are discussed in the coalescence model in comparison with the statistical model. We find that the yield of a hadron is typically an order of magnitude smaller when it is a compact multiquark state, compared to that of an excited hadronic state with normal quark numbers. We also find that some loosely bound hadronic molecules are formed more abundantly than the statistical model prediction by a factor of two or more. Moreover, due to the significant numbers of charm and bottom quarks produced at RHIC and even larger numbers expected at LHC, some of the proposed heavy exotic hadrons could be produced with sufficient abundance for detection, making it possible to study these new exotic hadrons in heavy ion collisions.

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A multi-pomeron exchange potential (MPP) is proposed as a model for the three-body repulsion indicated in neutron-star matter, which works universally among three-and four-baryons. Its strength is determined by analyzing the nucleus-nucleus scattering with the G-matrix folding model. The EoS in neutron matter is obtained including the MPP contribution. The neutron-star mass is calculated by solving the TOV equation. The maximum mass is obtained to be larger than the observed one 1.97M solar on the basis of the experimental data.

We investigate the two-particle intensity correlation function of in relativistic heavy-ion collisions. We find that the behavior of the correlation function at small relative momenta is fairly sensitive to the interaction potential and collective flows. By comparing the results of different source functions and potentials, we explore the effect of intrinsic collective motions on the correlation function. We find that the recent STAR data give a strong constraint on the scattering length and effective range of interaction, as −1.8 fm −1 < 1/a 0 < −0.8 fm −1 and 3.5 fm < r eff < 7 fm, respectively, if samples do not include the feed-down contribution from long-lived particles. We find that the feed-down correction for 0 decay reduces the sensitivity of the correlation function to the detail of the interaction. As a result, we obtain a weaker constraint, 1/a 0 < −0.8 fm −1 . Implication for the signal of existence of H -dibaryon is discussed. Comparison with the scattering parameters obtained from the double hypernucleus may reveal in-medium effects in the interaction.

Abstract. Neutron stars with large masses ∼ 2M⊙ require the hard stiffness of equation of state (EoS) of neutron-star matter. On the other hand, hyperon mixing brings about remarkable softening of EoS. In order to solve this problem, a multi-pomeron exchange potential (MPP) is introduced as a model for the universal many-body repulsion in baryonic systems on the basis of the Extended Soft Core (ESC) baryonbaryon interaction. The strength of MPP is determined by analyzing the nucleus-nucleus scattering with the G-matrix folding model. The interactions in ΛN , ΣN and ΞN channels are shown to be consistent with experimental indications. The EoS in neutron-star matter with hyperon mixing is obtained from ESC in addition of MPP, and mass-radius relations of neutron stars are derived. The maximum mass is shown to reach 2M⊙ even in the case of including hyperon mixing on the basis of model-parameters determined by terrestrial experiments. PACS

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