1/N_c and 1/n preasymptotic corrections to Current-Current correlators

Understand

We obtain the corrections in $1/n$ and in $1/\ln n$ ($n$ is the principal quantum number of the bound state) of the decay constants of scalar and pseudoscalar currents in two and four dimensions in the large $N_c$.

• We obtain them from the operator product expansion provided a model for the large $n$ mass spectrum is given.
• In the two-dimensional case the spectrum is known and the corrections obtained in this paper are model independent.
• We confirm these results by confronting them with the numerical solution of the 't Hooft model.