Critical phenomena of strange hadronic matter in the extended Zimanyi-Moszkowski model

We have studied the liquid-gas phase transition of warm strange hadronic matter (SHM) in the extended Zimanyi-Moszkowski model. We implement the Nijmegen soft-core potential model NSC97f of hyperon-hyperon interactions in terms of the (hidden) strange mesons. The saturation properties of pure and matter by the potential essentially determine the dependence of the critical temperature on the strangeness fraction of SHM. We treat the liquid-gas phase transition of SHM as the …rst-order one and employ Maxwell construction so as to calculate the phase coexistence curves. The derived critical exponents ' 1=3 and = 1:22 are almost independent of the strangeness fraction of SHM and almost agree with the empirical values derived from the recent multifragmentation reactions. Consequently, we have con…rmed the universality of the critical phenomena in the liquid-gas phase transition of hadronic system. 1 Introduction Recently, there are renewed interests [1,2] on the liquid-gas phase transition in nuclear medium. The evidences of the …rst-order phase transition have been observed in the plateau of the caloric curves [3] and the negative heat capacity [4] from nuclear multifragmentation reactions. Moreover, we have the information on the critical phenomena of the phase transition, the critical temperature TC [5-7] and the critical exponents and [6,8-10]. It is generally believed that the critical phenomena are universal. We can expect that the critical exponents are independent of the kinds of matter. In fact, their values for nuclear matter derived from multifragmentation reactions [10] agree with their universal values in molecular physics. This is the most prominent evidence of nuclear liquid-gas phase transitions, and so is really surprising because the energy and length scales and the underlying fundamental interaction in nuclear physics are essentially di¤erent from those in molecular physics. It is however noted [11] that in heavy-ion reactions the limit of Coulomb instability prevents the nuclear system from reaching the critical point. Therefore, the empirical E-mail : [email protected]