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an ideal gas of ’massive’ noninteracting quasiparticles. The mass of these quasiparticles is temperature-dependent and arises because of the interactions of quarks and gluons with the surrounding matter in the medium. These quasiparticles retain the quantum numbers of the real particles i.e., the quarks and gluons. It was assumed that energy ω and momentum k of the quasiparticles obey a simple dispersion relation : 

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where m(T) is the temperature-dependent mass of the quasiparticle. The pressure and energy density of the ideal gas of quasiparticles are dependent on ω and m ( T ) and are given by [15]: ∞ 

where d represents the degeneracy factor for quarks and/or gluons. However, Gorenstein and Yang pointed out that this model involves a thermodynamical inconsistency [15]. It did not satisfy the fundamental thermodynamic relation: ϵ ( T ) = T d p ( T ) dT − p ( T ). So they reformulated the statistical mechanics for a system whose constituents follow a medium- dependent dispersion relation and the above inconsistency problem was handled by them by introducing a temperature-dependent vacuum energy term which effectively cancelled the inconsistent term. Alternatively, Bannur also pointed out the reason for the above thermodynamical inconsistency [16]. If the particle mass in the system is not constant and it depends upon the medium, then the relation used between the pressure and grand canonical partition function does not hold good. So one can start from the definitions of the energy density and the average particle number density in the grand canonical ensemble formalism and in this way a different thermodynamically consistent quasiparticle model for QGP can be obtained. 

## III. FIRST QUASIPARTICLE MODEL (QPM I) 

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Gorenstein and Yang initially formulated a thermodynamically-consistent quasiparticle model for a gluon plasma at µ$_{B}$ =0 and later they extended it for the QGP having a finite value of µ$_{B}$ . In this model, the effective mass of the gluon changes with T and µ$_{B}$ as follows 

