Unwinding strings and T-duality of Kaluza–Klein and H-monopoles

A fundamental string with non-zero winding number can unwind in the presence of a Kaluza-Klein monopole. We use this fact to deduce the presence of a zero mode for the Kaluza-Klein monopole corresponding to excitations carrying H-electric charge and we study the coupling of this zero mode to fundamental strings. We also describe a T-dual process in which the momentum of a fundamental string "unwinds" in the presence of an H-monopole. We use the coupling of string winding modes to the dyon collective coordinate of the Kaluza-Klein monopole to argue that there are stringy corrections to the Kaluza-Klein monopole which are in accordance with T-duality.