(α')2 correction to the effective action of a boson string from the three-loopy β function of a nonlinear σ model with torsion
Ketov S. V., Samolov A. I.
The three-loop/? function of a nonlinear 2D σ model with a Wess-Zumino-Witten term satisfies the integrability condition. The results of a calculation of the (a')2 correction to the effective low-energy action of a boson string, with allowance for the antisymmetric Kalb-Ramon tensor field, are presented.