HET- seminar: Ruben Monten

Speaker:  Ruben Monten

Title: The TTbar deformation in AdS/CFT

Abstract: A large class of two-dimensional quantum fields theories contain an interesting operator built from the stress tensor, called ``TTbar''. Although this operator is irrelevant, adding it to the action generates a new family of theories in a controlled way. For the particular case of conformal field theories with an Anti-de Sitter holographic dual, it has been conjectured that TTbar-deformed theories correspond to the gravitational theory obtained by ``cutting off'' the region of AdS beyond a hypersurface of fixed radius. We will use the variational principle in the CFT to derive the holographic effect of the TTbar deformation at large N: mixed boundary conditions for the dual metric. This is consistent with the conjecture only for pure gravity and for a particular sign of the deformation parameter. When matter is present, the conjecture should be revised. The asymptotic symmetries of the gravitational theory with mixed boundary conditions form two Virasoro algebras, the generators of which are state-dependent but the central charge remains unchanged.