New Boundary Conformal Field Theories Indexed by the Simply-Laced Lie Algebras

TL;DR

This paper constructs and analyzes boundary conformal field theories in 1+1 dimensions, indexed by simply-laced Lie algebras, with explicit boundary states and correlation functions, relevant to string theory and quantum Hall physics.

Contribution

It introduces a class of boundary conformal field theories associated with simply-laced Lie algebras, providing explicit boundary states and demonstrating conformal invariance for special gauge and potential choices.

Findings

Conformal invariance is preserved for specific gauge and potential configurations.

Explicit boundary states are constructed for each Lie algebra case.

Partition functions and correlators are computed explicitly.

Abstract

We consider the field theory of $N$ massless bosons which are free except for an interaction localized on the boundary of their 1+1 dimensional world. The boundary action is the sum of two pieces: a periodic potential and a coupling to a uniform abelian gauge field. Such models arise in open string theory and dissipative quantum mechanics, and possibly in edge state tunneling in the fractional quantized Hall effect. We explicitly show that conformal invariance is unbroken for certain special choices of the gauge field and the periodic potential. These special cases are naturally indexed by semi-simple, simply laced Lie algebras. For each such algebra, we have a discrete series of conformally invariant theories where the potential and gauge field are conveniently given in terms of the weight lattice of the algebra. We compute the exact boundary state for these theories, which explicitly shows the group structure. The partition function and correlation functions are easily computed using the boundary state result.