  Despite impressive advances in the AdS3/CFT2 correspondence, the setup
involving Ramond-Ramond backgrounds, which is related to the D1-D5 system of
branes, remained relatively poorly understood. We use the Mirror TBA equations
recently constructed by Frolov and Sfondrini to study the spectrum of pure
Ramond-Ramond $AdS_3\times S^3\times T^4$ strings. We find that the
leading-order contribution to the anomalous dimensions at small tension is due
to the gapless worldsheet excitations, i.e. to the $T^4$ bosons and their
superpartners, whose interactions are nontrivial.
