Looking for defects in the 2PI correlator

Truncations of the 2PI effective action are seen as a promising way ofstudying non-equilibrium dynamics in quantum field theories. We probe theirapplicability in the non-perturbative setting of topological defect formationin a symmetry-breaking phase transition, by comparing full classical latticefield simulations and the 2PI formulation for classical fields in an O($N$)symmetric scalar field theory. At next-to-leading order in 1/N, the 2PIformalism fails to reproduce any signals of defects in the two-point function.This suggests that one should be careful when applying the 2PI formalism forsymmetry breaking phase transitions.Comment: 22 pages, 6 figure