A New Approach for Calculating Spin Susceptibility in QED3

Based on the study of the linear response of the fermion propagatorto the presence of an external scalar field, a new method for calculatingthe staggered spin susceptibility in QED₃ is presented, in which the influence of the full vertex function is included. The numerical values of the staggered spin susceptibility are calculated within the framework of the rainbow-ladder approximation of the Dyson-Schwinger approach. A comparison between the result calculated using the full vertex and that using the bare vertex is given.