Harmonic crossover exponents in O(n) models with the pseudo-epsilon   expansion approach
  We determine the crossover exponents associated with the traceless tensorial quadratic field, the third- and fourth-harmonic operators for O(n) vector models by re-analyzing the existing six-loop fixed dimension series with pseudo-epsilon expansion. Within this approach we obtain the most accurate theoretical estimates that are in optimum agreement with other theoretical and experimental results. 
Pasquale Calabrese and Pietro Parruccini