Peak of Chiral Susceptibility and Chiral Phase Transition in QED₃

A general expression for the scalar susceptibility in QED₃ is given. We adopt the Dyson–Schwinger equation for the fermion propagator to solve χ^c within a range of the number of fermion flavors, N, in chiral symmetry breaking phase. We show that the scalar susceptibility has a peak and the corresponding N is less than the critical number of fermion flavors for chiral symmetry.