On the singularities of the R-R AdS(3) x S-3 x T-4 S matrix

We investigate the analytic properties of the exact magnon S matrix of string theory on AdS(3) x S-3 x T-4 with R-R flux. We show that the previously proposed dressing factors have the exact double-pole/zero structure expected from Landau box diagrams. This constitutes a strong consistency check of our dressing factors, much as the Dorey-Hofman-Maldacena poles do for the all-loop dressing factor in AdS(5) x S-5.