Speaker
Description
We initiate a systematic study of multipoint defect correlators using the lightcone bootstrap, focusing on the simplest non-trivial example: a bulk–bulk–defect three-point function. We analyze the associated crossing equation, which relates the bulk and defect channels, in the lightcone kinematical regime where one bulk insertion approaches the lightcone of the other. In this limit, we derive a closed-form expression for the bulk conformal blocks in terms of a Lauricella function, while the defect conformal blocks are known. By studying the crossing equation in appropriate kinematical regimes, we identify the defect-channel spectrum required to reproduce the leading-twist bulk exchange. In addition to the familiar tower of transverse-twist defect operators, consistency of crossing demands the presence of a new family of mixed bulk–defect double-twist operators, whose twist equals the sum of the conformal dimensions of the external bulk and defect operators. Finally, we obtain a closed asymptotic expression for a particular combination of bulk-to-defect OPE coefficients.