Demystifying the Massless Sector in AdS_3 Quantum Spectral Curve

We show that in the asymptotic large-volume limit, the original proposal for Quantum Spectral Curve for AdS3 x S3 x T4 with R-R flux has a wider class of solutions, than studied previously. We argue that in this limit the QSC reduces to a finite set of Bethe equations for both massive and massless particle types. We also find that the QSC imposes more constraining conditions on the dressing phases than previously known and we present solutions of those equations.