Reflection factors and exact g-functions for purely elastic scattering theories
Patrick Dorey, Anna Lishman, Chaiho Rim, Roberto Tateo
TL;DR
This work develops an exact off-critical g-function framework to connect reflection factors of purely elastic boundary theories (ADE and T_r) with perturbed boundary conformal field theories. It constructs minimal and one-parameter families of reflection factors, relates one-parameter deformations to boundary RG flows, and validates the framework through UV g-function checks against coset/CFT data, CPT, and specific models like the three-state Potts model. The results establish a UV/IR dictionary for a broad class of integrable boundary theories and reveal systematic flows between conformal boundary conditions, including symmetry-factor effects in multi-vacua systems. The approach also links boundary reflection data to reductions of sine-Gordon theory, strengthening the physical interpretation of the proposed reflection factors and providing a roadmap for future analyses of boundary bound states and UV/IR couplings.
Abstract
We discuss reflection factors for purely elastic scattering theories and relate them to perturbations of specific conformal boundary conditions, using recent results on exact off-critical g-functions. For the non-unitary cases, we support our conjectures using a relationship with quantum group reductions of the sine-Gordon model. Our results imply the existence of a variety of new flows between conformal boundary conditions, some of them driven by boundary-changing operators.
