Universal Subleading Spectrum of Effective String Theory

TL;DR

The paper analyzes the Polchinski–Strominger effective string in D dimensions under Poincaré invariance to study the long-string spectrum around a wrapped string. By enforcing conformal invariance and central-charge constraints, it derives a universal $R^{-3}$ correction to the ground-state energy that matches the Nambu–Goto form, with the central charge fixed to $26$ via $12\beta + D = 26$ and $\beta=(26-D)/12$. The Virasoro algebra and mode construction show the spectrum up to $O(R^{-3})$ is fixed and parameter-free at this order. These results provide a robust, lattice-testable prediction for flux-tube spectra and illustrate how spacetime symmetry imposes strong constraints on effective string theories beyond the Casimir term.

Abstract

We analyse the spectrum of the D-dimensional Poincare invariant effective string model of Polchinski and Strominger. It is shown that the leading terms beyond the Casimir term in the long distance expansion of the spectrum have a universal character which follows from the constraint of Poincare invariance.