HET Journal club: Sourav Sarkar

Speaker: Sourav Sarkar

Title: Universality at large transverse spin in defect CFT

Abstract: In the context of CFTs with a defect of co-dimension greater than one, we shall analize the lightcone limit of the crossing equation between the bulk and defect channel expansions of the bulk two point function and show that every such defect theory admits a large “transverse spin” (s) expansion. "Transverse spin" is the spin associated with the Lorentz transformations in the bulk that preserve the defect. We shall see the existence of towers of operators in a generic defect spectrum whose anomalous dimensions and OPE coefficients can be expanded around a universal value in orders of 1/s, analogous to the large spin expansion for "double twist operators" in CFT without defects. We shall also discuss a Lorentzian inverse of the defect channel OPE which gives us an analytic formula in s for the anomalous dimensions and OPE coefficients, thus resumming the 1/s expansion obtained from the lightcone bootstrap.