Long strings and chiral primaries in the hybrid formalism

TL;DR

This paper uses the hybrid formalism to show that certain spectral gaps and long string phenomena in AdS3 string theory with pure NS-NS flux vanish when slightly perturbing away from this background, clarifying the spectrum's behavior.

Contribution

It provides a direct worldsheet demonstration that spectral gaps and long string effects disappear in mixed flux backgrounds, advancing understanding of AdS3 string spectra.

Findings

Spectral gaps in BPS spectrum vanish with flux perturbation

Long strings can no longer escape to the boundary in mixed flux backgrounds

Hybrid formalism effectively captures spectrum changes

Abstract

We revisit two related phenomena in $\mathrm{AdS}_3$ string theory backgrounds. At pure NS-NS flux, the spectrum contains a continuum of long strings which can escape to the boundary of $\mathrm{AdS}_3$ at a finite cost of energy. Related to this are certain gaps in the BPS spectrum one computes from the RNS worldsheet description. One expects that both these effects disappear when perturbing slightly away from the pure NS-NS flux background. We employ the hybrid formalism for mixed flux backgrounds to demonstrate directly from the worldsheet that this is indeed the case.