HET seminar: Alexander Zhiboedov
Speaker: Alexander Zhiboedov
Title: Conformal Bootstrap At Large Charge
Abstract: We consider unitary CFTs with continuous global symmetries in d>2. We consider a state created by the lightest operator of large charge Q>>1 and analyze the correlator of two light charged operators in this state. We assume that the correlator admits a well-defined large Q expansion and, relatedly, that the macroscopic (thermodynamic) limit of the correlator exists. We find that the crossing equations admit a consistent truncation, where only a finite number N of Regge trajectories contribute to the correlator at leading nontrivial order. We classify all such truncated solutions to the crossing. For one Regge trajectory N=1, the solution is unique and given by the effective field theory of a Goldstone mode. For two or more Regge trajectories N≥2, the solutions are encoded in roots of a certain degree N polynomial. Some of the solutions admit a simple weakly coupled EFT description, whereas others do not. In the weakly coupled case, each Regge trajectory corresponds to a field in the effective Lagrangian.