Schwinger Pair Production in QCD from Flavor-Dependent Contact Interaction Model of Quarks

Abstract

We study the Schwinger mechanism in QCD i.e., the quark-antiquark pair production rate $\Gamma$ in the presence of pure electric field strength $eE$, for a higher number of colors $N_c$ and flavors $N_f$. In this context, our unified formalism is based on the Schwinger-Dyson equations, flavor-dependent symmetry preserving vector-vector contact interaction model of quarks, and an optimal time regularization scheme. For fixed $N_c=3$ and $N_f=2$, the dynamically quark mass decreases as we increase $eE$ and near at and above the pseudo-critical electric field $e{E}_c$, the chiral symmetry is restored and quarks becomes unconfined. The pair production rate $\Gamma$ becomes stable and grows quickly above $e{E}_c$. For fixed $N_c=3$ and upon increasing $N_f$ the dynamical mass suppresses and as a result, the $e{E}_c$ reduces to its smaller values, the pair production rate $\Gamma$ tends to initiates and grows quickly for smaller values of $e{E}_c$. In contrast, for fixed $N_f=2$ and upon increasing $N_c$, the dynamical chiral symmetry is restored for larger and larger values of $e{E}_c$ and at $N_c\ge 4$, the transition changes from smooth cross-over to the first order at some critical endpoint ($N_{c,p},e{E}_{c,p}$). Consequently, the quark-antiquark production rate $\Gamma$ needs higher values of $e{E}_c$ for the stable and quick growth as we increase $N_c$. Our findings are satisfactory and in agreement with already predicted results for pair production rate (for fixed $N_c=3$ and $N_f=2$) by other reliable effective models of QCD.

Comments: 15 pages, 12 Figures