Instability in scalar channel of fermion-antifermion scattering   amplitude in massless QED_3 and anomalous dimensions of composite operators
  Instability in the scalar channel of the fermion-antifermion scattering amplitude in massless QED_3 for number of flavours less than the critical value 128/3\pi^2 is demonstrated. The anomalous dimensions of gauge-invariant composite operators are determined to O(1/N). Exponentiation of the O(1/N) infrared logarithm is explicitly demonstrated by evaluating the contribution of the ladder diagrams. 
Indrajit Mitra, Raghunath Ratabole and H. S. Sharatchandra