Journal Club : Multiparticle Factorization and the Rigidity of String Theory - Carolina Figueiredo

"The question of uniqueness of string theory has seen renewed interest over the last few years with the proposal of new deformations of string amplitudes. These deformations are families of amplitudes that show similar properties such as exponential softness, Regge behavior, and factorization on massless poles. In this talk, we will explain how asking for consistent factorization of higher point amplitudes on massive string modes allows us to exclude most of these deformations (arXiv:2312.07652). The crucial ingredient that facilitates this study is the parametrization of string amplitudes in terms of “u-variables” and their respective positive parameterizations. Under this framework, we also explain how one can use these variables to easily build new deformations of string amplitudes that satisfy all the constraints mentioned above, but that might still fail the higher-point factorization constraints."