Exact Partition Function and Boundary State of Critical Ising Model with Boundary Magnetic Field

Abstract

We compute the exact partition function of the 2D Ising Model at critical temperature but with nonzero magnetic field at the boundary. The model describes a renormalization group flow between the free and fixed conformal boundary conditions in the space of boundary interactions. For this flow the universal ground state degeneracy $g$ and the full boundary state is computed exactly.Comment: Two lines in the Introduction and three references adde