1/N Expansion for Critical Exponents of Magnetic Phase Transitions in CP^{N-1} Model at 2<d<4

Abstract

Critical exponents in the CP^{N-1} model, which describes localized-moment ferro- and antiferromagnets (N=2 in the Heisenberg model), are calculated from two-particle Green's functions to first order in 1/N. For d=2+\epsilon the results agree with earlier renormalization group calculations. For d=3 the leading 1/N-corrections turn out to be very large at N=2. For d=4-\epsilon the 1/N-corrections are small at any N and insufficient to describe correctly the magnetic phase transition.