Eur. Phys. J. A (2011) 47: 104
https://doi.org/10.1140/epja/i2011-11104-6

Regular Article - Theoretical Physics

Hadron-quark phase coexistence in a hybrid MIT-Bag model

¹ Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, 730000, Lanzhou, PRC
² Theoretical Physics Center for Scientific Facilities, Chinese Academy of Sciences, 100049, Beijing, PRC
³ Institute of High Energy Physics, Chinese Academy of Sciences, 100049, Beijing, PRC
⁴ Laboratori Nazionali del Sud INFN, I-95123, Catania, Italy
⁵ Physics and Astronomy Department, University of Catania, Catania, Italy
⁶ School of Science, Huzhou Teachers College, 313000, Huzhou, PRC
⁷ Institute of Modern Physics, Fudan University, 200433, Shanghai, PRC

^* e-mail: ditoro@lns.infn.it

Received: 21 April 2011
Revised: 28 June 2011
Accepted: 18 August 2011
Published online: 13 September 2011

Abstract

The phase transition of hadronic to quark matter and the boundaries of the hadron-quark coexistence phase are studied within the two Equation of State (EoS) models. The relativistic effective mean-field approach with constant and density-dependent meson-nucleon couplings is used to describe hadronic matter, and the MIT-Bag model is adopted to describe quark matter. The boundaries of the mixed phase for different Bag constants are obtained solving the Gibbs equations. We notice that the dependence on the Bag parameter of the critical temperatures (at zero chemical potential) can be well reproduced by a fermion ultrarelativistic quark gas model, without contribution from the hadron part. At variance, the critical chemical potentials (at zero temperature) are very sensitive to the EoS of the hadron sector. Hence, the contribution of the hadronic interaction is much more relevant for the determination of the transition to the quark-gluon plasma at finite baryon density and low T . Moreover, in the low-temperature and finite chemical potential region no solutions of the Gibbs conditions are existing for small Bag-constant values, B < (135 MeV)⁴ . Isospin effects in asymmetric matter appear important in the high chemical-potential regions at lower temperatures, of interest for the inner-core properties of neutron stars and for heavy-ion collisions at intermediate energies.