Finite-size corrections in the SU(2) x SU(2) sector of type IIA string   theory on AdS_4 x CP^3
  We consider finite-size corrections in the SU(2) x SU(2) sector of type IIA string theory on AdS_4 x CP^3, which is the string dual of the recently constructed N=6 superconformal Chern-Simons theory of Aharony, Bergman, Jafferis and Maldacena (ABJM theory). The string states we consider are in the R x S^2 x S^2 subspace of AdS_4 x CP^3 with an angular momentum J on CP^3 being large. We compute the finite-size corrections using two different methods, one is to consider curvature corrections to the Penrose limit giving an expansion in 1/J, the other by considering a low energy expansion in lambda'=lambda/J^2 of the string theory sigma-model, lambda being the 't Hooft coupling of the dual ABJM theory. For both methods there are interesting issues to deal with. In the near-pp-wave method there is a 1/\sqrt{J} interaction term for which we use zeta-function regularization in order to compute the 1/J correction to the energy. For the low energy sigma-model expansion we have to take into account a non-trivial coupling to a non-dynamical transverse direction. We find agreement between the two methods. At order lambda' and lambda'^2, for small lambda', our results are analogous to the ones for the SU(2) sector in type IIB string theory on AdS_5 x S^5. Instead at order lambda'^3 there are interactions between the two two-spheres. We compare our results with the recently proposed all-loop Bethe ansatz of Gromov and Vieira and find agreement. 
Davide Astolfi, Valentina Giangreco M. Puletti, Gianluca Grignani,   Troels Harmark and Marta Orselli