Defect Lines in the Ising Model and Boundary States on Orbifolds

TL;DR

This paper explores how defect lines in the 2D Ising model influence boundary states and critical phenomena, revealing new universality classes and boundary behaviors through boundary conformal field theory on orbifolds.

Contribution

It introduces novel boundary states and critical exponents arising from orbifold structures, expanding understanding of defect lines in the Ising model.

Findings

Discovery of a new universality class of defect lines

Universal boundary to bulk crossover of spin correlations

Continuously varying boundary critical exponents

Abstract

Critical phenomena in the two-dimensional Ising model with a defect line are studied using boundary conformal field theory on the $c=1$ orbifold. Novel features of the boundary states arising from the orbifold structure, including continuously varying boundary critical exponents, are elucidated. New features of the Ising defect problem are obtained including a novel universality class of defect lines and the universal boundary to bulk crossover of the spin correlation function.