Conformal Toda theory with a boundary

TL;DR

This paper studies boundary conditions in conformal Toda theory, classifies D-branes, and analyzes their properties using classical and bootstrap methods, revealing intricate fusion behaviors and divergences.

Contribution

It provides a comprehensive analysis of maximally symmetric boundary conditions in sl(n) Toda theory, including D-brane classification and bootstrap results.

Findings

Existence of D-branes of all dimensions 0 to n-1.

Determination of bulk one-point functions.

Observation of severe divergences in partition functions.

Abstract

We investigate sl(n) conformal Toda theory with maximally symmetric boundaries. There are two types of maximally symmetric boundary conditions, due to the existence of an order two automorphism of the W(n>2) algebra. In one of the two cases, we find that there exist D-branes of all possible dimensions 0 =< d =< n-1, which correspond to partly degenerate representations of the W(n) algebra. We perform classical and conformal bootstrap analyses of such D-branes, and relate these two approaches by using the semi-classical light asymptotic limit. In particular we determine the bulk one-point functions. We observe remarkably severe divergences in the annulus partition functions, and attribute their origin to the existence of infinite multiplicities in the fusion of representations of the W(n>2) algebra. We also comment on the issue of the existence of a boundary action, using the calculus of constrained functional forms, and derive the generating function of the B"acklund transformation for sl(3) Toda classical mechanics, using the minisuperspace limit of the bulk one-point function.