The AdS(n) x S(n) x T(10-2n) BMN string at two loops
arXiv:1508.04313 · doi:10.1007/JHEP11(2015)154
Abstract
We calculate the two-loop correction to the dispersion relation for worldsheet modes of the BMN string in AdS(n) x S(n) x T(10-2n) for n=2,3,5. For the massive modes the result agrees with the exact dispersion relation derived from symmetry considerations with no correction to the interpolating function h. For the massless modes in AdS(3) x S(3) x T(4) however our result does not match what one expects from the corresponding symmetry based analysis. We also derive the S-matrix for massless modes up to the one-loop order. The scattering phase is given by the massless limit of the Hernandez-Lopez phase. In addition we compute a certain massless S-matrix element at two loops and show that it vanishes suggesting that the two-loop phase in the massless sector is zero.
30 pages, 6 figures; v2: References and comment on type IIB added, acknowledgements updated; v3: Comparison to proposed exact massless S-matrix in sec 5.3 corrected. Only non-trivial phase appears at one loop. Additional minor clarifications