The Annular Report on Non-Critical String Theory
Emil J. Martinec
TL;DR
This work uses the Liouville annulus partition function with boundary Liouville and matter states to connect non-critical string theories across $c\le 1$ to their matrix-model duals, reproducing macroscopic-loop correlators and leading non-perturbative effects via D-brane (disk) boundary data. It further extends the framework to supercritical strings ($d\ge 25$), where Liouville gravity on the worldsheet realizes 2d de Sitter gravity and annulus amplitudes encode the de Sitter S-matrix between asymptotic boundaries. The analysis clarifies the dual role of matrix eigenvalues as Liouville D-branes and identifies boundary states with D-instanton sectors, while providing a controlled path to de Sitter amplitudes and wavefunctions through boundary-bulk factorization and minisuperspace limits. The results strengthen the Liouville-matrix-model correspondence and illuminate the structure of quantum gravity in two dimensions, including implications for a potential matrix-model description of 2d de Sitter cosmology.
Abstract
Recent results on the annulus partition function in Liouville field theory are applied to non-critical string theory, both below and above the critical dimension. Liouville gravity coupled to $c\le 1$ matter has a dual formulation as a matrix model. Two well-known matrix model results are reproduced precisely using the worldsheet formulation: (1) the correlation function of two macroscopic loops, and (2) the leading non-perturbative effects. The latter identifies the eigenvalue instanton amplitudes of the matrix approach with disk instantons of the worldsheet approach, thus demonstrating that the matrix model is the effective dynamics of a D-brane realization of $d\le 1$ non-critical string theory. In the context of string theory above the critical dimension, i.e. $d\ge 25$, Liouville field theory realizes two-dimensional de Sitter gravity on the worldsheet. In this case, appropriate D-brane boundary conditions on the annulus realize the S-matrix for two-dimensional de Sitter gravity.
