In order to better understand the space of quantum field theories, it is useful to deform old QFTs and obtain new ones. In this talk, we will discuss a class of deformations of two-dimensional QFTs which are constructed from the stress-energy tensor and are thus universal; examples include the irrelevant TT operator and the marginal root-TT operator. In many cases, these deformations lead to simple closed-form expressions for quantities like the Lagrangian or finite-volume spectrum. Furthermore, they often preserve desirable structures like supersymmetry and integrability.
INFN & DFA