Influence of finite chemical potential on the fermion chiral condensate in QED3

In this Letter, we generalize our previous work [H.T. Feng, F.Y. Hou, X. He, W.M. Sun, H.S. Zong, Phys. Rev. D 73 (2006) 016004] on the effect of finite chemical potential μ on the fermion propagator in QED3 from the rainbow approximation (bare vertex approximation) of the Dyson-Schwinger approach to the case of an improved fermion-photon vertex ansatz. We show that, for this choice of the fermion-photon vertex the fermion propagator at finite chemical potential can still be written as Sˆ−1(μ,p)=iγ⋅p˜A(p˜2)+B(p˜2), where p˜=(p→,p3+iμ) and S−1(p)=iγ⋅pA(p2)+B(p2) is the fermion propagator at μ=0. By application of this result, the fermion chiral condensate is evaluated for the range N∈[0,3.0] (N denotes the number of fermion flavors) and μ∈[0,10−2] and the influence of small chemical potential on the critical number of fermion flavors Nc is analyzed. A comparison with the rainbow approximation results is made.