Superstrings in AdS(n) x S(n) x T(10-2n) at one- and two-loops
OKC/Nordita High-Energy Physics Theory seminar
Monday 09 February 2015
to 14:15 at
Per Sundin (Milano-Bicocca)
In many cases of integrable AdS / CFT the dispersion relation and S-matrix can (up to some scalar functions) be determined / guessed by symmetry arguments alone. In this talk I will discuss recent developments in how to compute these ingredients perturbatively from the worldsheet of the string sigma-model. Naively some quantities diverge on the worldsheet and in order to render them finite one should implement wave-function renormalization of some of the bosonic coordinates. Furthermore, there is an ambiguity in how to regularize the theory and I will discuss how to identify the proper regularization scheme consistent with the underlying symmetries of the problem. A novel feature of the less symmetric examples of AdS / CFT is the existence of massless excitations, corresponding to supersymmetries broken by the background. I will demonstrate that in the physical regularization-scheme the massive sector decouples from the massless and can (at least up to the two-loop level) be described by a coset sigma-model. Finally I will discuss an apparent mismatch in the massless sector between the proposed exact solution and perturbative data.