An improved AFS phase for AdS3 string integrability

We propose a number of modifications to the classical term in the dressing phase for integrable strings in AdS3×S3×S3×S1AdS3×S3×S3×S1, and check these against existing perturbative calculations, crossing symmetry, and the semiclassical limit of the Bethe equations. The principal change is that the phase for different masses should start with a term Q1Q2Q1Q2, like the one-loop AdS3AdS3 dressing phase, rather than Q2Q3Q2Q3 as for the original AdS5AdS5 AFS phase.