The Strong Coupling Limit of the Scaling Function from the Quantum String Bethe Ansatz
Abstract
Using the quantum string Bethe ansatz we derive the one-loop energy of a folded string rotating with angular momenta (S,J) in AdS3 x S1 inside AdS5 x S5 in the limit 1 << J << S, z=λ(1/2) log(S/J) /(π J) fixed. The one-loop energy is a sum of two contributions, one originating from the Hernandez-Lopez phase and another one being due to spin chain finite size effects. We find a result which at the functional level exactly matches the result of a string theory computation. Expanding the result for large z we obtain the strong coupling limit of the scaling function for low twist, high spin operators of the SL(2) sector of N=4 SYM. In particular we recover the famous -3 log(2)/π. Its appearance is a result of non-trivial cancellations between the finite size effects and the Hernandez-Lopez correction.