MIT bag model

One important condition is constituted by the fact that certainly in symmetric nuclear matter no phase transition is observed below 3po- In fact some theoretical interpretation of the heavy ion experiments performed at the CERN SPS [30] points to a possible phase transition at a critical density pc ss 6po ss 1/fm3. We will in the following take this value for granted and use an extended MIT bag model [31] (requiring a density dependent bag constant ) that is compatible with this condition. 

We first review briefly the description of the bulk properties of uniform quark matter, deconfined from the /3-stable hadronic matter mentioned in the previous section, by using the MIT bag model [31]. The thermodynamic potential of f = u,d,s quarks can be expressed as a sum of the kinetic term and the one-gluon-exchange term [32, 33] proportional to the QCD fine structure... 

In the original MIT bag model the bag constant B 55 MeV fm-3 is used, while values B 210 MeV fm-3 are estimated from lattice calculations [34], In this sense B can be considered as a free parameter. We found, however, that a bag model involving a constant (density independent) bag parameter B, combined with our BHF hadronic EOS, will not yield the required phase transition in symmetric matter at pr 6po 1/fm3 [28]. This can only be accomplished by introducing a density dependence of the bag parameter. (The dependence on asymmetry is neglected at the current level of investigation). In practice we use a Gaussian parameterization,... 

A pure quark phase above 1015g/cm3 where the MIT-bag-model EoS applied. 1 4/3... 

Figure 1. Chemical potentials of the three phases of matter (H, Q, and Q ), as defined by Eq. (2) as a function of the total pressure (left panel) and energy density of the H- and Q-phase as a function of the baryon number density (right panel). The hadronic phase is described with the GM3 model whereas for the Q and Q phases is employed the MIT-like bag model with ms = 150 MeV, B = 152.45 MeV/fm3 and as = 0. The vertical lines arrows on the right panel indicate the beginning and the end of the mixed hadron-quark phase defined according to the Gibbs criterion for phase equilibrium. On the left panel P0 denotes the static transition point.

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