$π$- and $K$-meson properties for large $N_f$ and $N_c$

Abstract: Dynamical chiral symmetry restoration for higher number of light quark flavors $N_f$ and breaking for higher number of colors $N_c$ implies the suppression and enhancement of the dynamically generated quark mass. The study of various larger values of number of colors and flavors may have greater impact on the internal structure of light hadrons. In this work, we study the properties of the pion and kaon, such as mass, condensate, and leptonic decay constant, for various $N_f$ and $N_c$. We use the symmetry-preserving vector-vector flavor-dependent contact interaction model of quark. The dynamical quark masses are calculated by using the Schwinger-Dyson equation (SDE). The masses of the pion and kaon for different values of $N_f$ and $N_c$ are determined using the homogeneous Bethe-Salpeter equation. For fixed $N_f=2$ and $N_c$ is increased, the dynamically generated quark mass ( mass of up and down quarks), strange quark mass, meson in-condensate, and decay constant, all increases. The pion mass remains approximately constant until $N_c$ reaches around 6.5, after which it grows rapidly. On the other hand, the kaon mass increases slowly with increasing $N_c$ until it reaches approximately $N_c=7.5$, beyond which it rises quickly. When $N_c=3$ is fixed at and various values of $N_f$ are considered, all the parameter values decrease as a function of $N_f$, except for the pion and kaon mass, which increase above a critical value of $N_f$ around $8$. This is the region where chiral symmetry is restored, and the pion and kaon behave as free particles, similar to their behavior in the presence of a heat bath. The results obtained for fixed $N_f=2$ and $N_c=3$ are fairly in decent agreement with experimentally calculated statistics and previous model calculations based on the Schwinger-Dyson equation (SDE) and Bethe-Salpeter equation (BSE).