An SL(2, Z) Multiplet of Type IIB Super Five-Branes
It is well-known that the low energy string theory admits a non-singular solitonic super five-brane solution which is the magnetic dual to the fundamental string solution. By using the symmetry of the type IIB string theory, we construct an SL(2, Z) multiplet of magnetically charged super five-branes starting from this solitonic solution. These solutions are characterized by two integral three-form charges $(q_1, q_2)$ and are stable when the integers are coprime. We obtain an expression for the tension of these $(q_1, q_2)$ five-branes as envisaged by Witten. The SL(2, Z) multiplets of black strings and black fivebranes and the existence of similar magnetic dual solutions of strings in type II string theory in $D < 10$ have also been discussed.