Structure function, susceptibility and correlation lengths at critical points for infinite strips with periodic boundary conditions

The authors employ the results of conformal invariance at critical points to calculate the structure friction S(k), bulk susceptibility x and correlation lengths (defined via moments of the correlation function) for infinite strips with periodic boundaries. Analytic formulae for operators with anomalous dimension 0<or=x<or=1 are obtained. The correction to the leading asymptotic form of S for large mod k mod is determined. The convergence to the leading 1/k 2-2x behaviour is shown to depend on x and be slow for x=1/8 the Ising spin-spin correlation function value. For x=1, S is found to display a logarithmic lineshape.