On string theory on deformed BTZ and TT¯

Aspects of superstring theory on deformed BTZ black holes, formed near k NS5 branes by p fundamental strings, and single-trace TT¯ holography, are presented. The excitation energy of a singly wound long string plus its contribution to the energy of the black hole, 1/p fraction of the black-hole energy, is the same as that in TT¯ deformed CFT₂ with c = 6k. This supports the claim that the black hole can be thought of as a state in a symmetric product of p CFT₂’s of central charge 6k, where the black-hole energy is split equally among all p factors. A comment on superstring theory on deformed global AdS₃ is also presented.