Physics beyond instantons. Measuring the physical correlation length

Summary, in English

In broken-symmetry phases of models with discrete global symmetry, the physical correlation length can be measured using time-slice correlators projected to non-zero momenta. A transfer matrix based argument is used to construct the finite-size scaling for this quantity. We extract the correlation length for the two-dimensional ten-state Potts model by this means, and the surface tension from the zero-momentum correlator.