  It has recently been argued that the symmetric orbifold theory of T4 is dual
to string theory on AdS3 x S3 x T4 at the tensionless point. At this point in
moduli space, the theory possesses a very large symmetry algebra that includes,
in particular, a $W_\infty$ algebra capturing the gauge fields of a dual higher
spin theory. Using conformal perturbation theory, we study the behaviour of the
symmetry generators of the symmetric orbifold theory under the deformation that
corresponds to switching on the string tension. We show that the generators
fall nicely into Regge trajectories, with the higher spin fields corresponding
to the leading Regge trajectory. We also estimate the form of the Regge
trajectories for large spin, and find evidence for the familiar logarithmic
behaviour, thereby suggesting that the symmetric orbifold theory is dual to an
AdS background with pure RR flux.
