The rigid symmetries of bosonic D-strings

We analyse the classical symmetries of bosonic D-string actions and generalizations thereof. Among others, we show that the simplest actions of this type have infinitely many nontrivial rigid symmetries which act nontrivially and nonlinearly both on the target space coordinates and on the U(1) gauge field, and form a Kač-Moody version of the Weyl algebra (= Poincaré algebra + dilatations).