What are T-Tbar deformations?

ABSTRACT
The presence of an irrelevant field in a quantum field theory is usually not good news, as far as understanding the high-energy physics of the model is concerned. In two space-time dimensions, the T-Tbar deformation is solvable. We can describe physical observables of interest, such as the S-matrix and the finite-volume spectrum, in terms of the corresponding undeformed quantities. For this irrelevant perturbation, we can reverse the renormalization group trajectory and gain exact information about ultraviolet physics. The outcome is stunning: low-energy physics resembles that of a conventional local quantum field theory while at high-energy the density of states on a cylinder shows Hagedorn growth similar to that of a string theory.

BIO
Roberto Tateo is full Professor at the University of Torino. He is mainly working on integrable models and their applications to the AdS/CFT duality, the ODE/IM correspondence and PT-symmetry. He received his PhD in Physics in 1994 and worked as a Postdoc at the University of Durham, the University of Amsterdam, and at the Service de Physique Théorique in Saclay.

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