Vector-like contributions from Optimized Perturbation in the Abelian Nambu--Jona-Lasinio model for cold and dense quark matter - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue International Journal of Modern Physics E Année : 2012

Vector-like contributions from Optimized Perturbation in the Abelian Nambu--Jona-Lasinio model for cold and dense quark matter

Jean-Loïc Kneur
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Marcus Benghi Pinto
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Rudnei O. Ramos
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Ederson Staudt
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Résumé

Two-loop corrections for the standard Abelian Nambu-Jona-Lasinio model are obtained with the Optimized Perturbation Theory (OPT) method. These contributions improve the usual mean-field and Hartree-Fock results by generating a $1/N_c$ suppressed term, which only contributes at finite chemical potential. We take the zero temperature limit observing that, within the OPT, chiral symmetry is restored at a higher chemical potential $\mu$, while the resulting equation of state is stiffer than the one obtained when mean-field is applied to the standard version of the model. In order to understand the physical nature of these finite $N_c$ contributions, we perform a numerical analysis to show that the OPT quantum corrections mimic effective repulsive vector-vector interaction contributions. We also derive a simple analytical approximation for the mass gap, accurate at the percent level, matching the mean-field approximation extended by an extra vector channel to OPT. For $\mu \gtrsim \mu_c$ the effective vector coupling matching OPT is numerically close (for the Abelian model) to the Fierz-induced Hartree-Fock value $G/(2N_c)$, where $G$ is the scalar coupling, and then increases with $\mu$ in a well-determined manner.

Dates et versions

hal-00700781 , version 1 (23-05-2012)

Identifiants

Citer

Jean-Loïc Kneur, Marcus Benghi Pinto, Rudnei O. Ramos, Ederson Staudt. Vector-like contributions from Optimized Perturbation in the Abelian Nambu--Jona-Lasinio model for cold and dense quark matter. International Journal of Modern Physics E, 2012, 21 (3), pp.1250017. ⟨10.1142/S0218301312500176⟩. ⟨hal-00700781⟩
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