Flavor dependence of chiral symmetry breaking and the conformal window

We investigate the phase structure of QCD in the vacuum as a function of quark flavor number N f within the chiral limit. By self-consistently solving the coupled Dyson-Schwinger equations for the quark and gluon propagators in a minimal QCD scheme, we elucidate the nonperturbative dynamics governing dynamical chiral symmetry breaking. Our calculations determine a critical flavor number of N f c = 6.81 which marks the chiral symmetry restoration of quarks. Further analysis reveals the critical exponents of the chiral condensate as − ⟨ ψ ¯ ψ ⟩ ∼ | N f − N f c | 0.53 ( 9 ) , characterized the second order feature of this phase transition of chiral symmetry. Additionally, we discuss the implications for the walking regime towards the conformal window at larger flavor.