String theory duals for mass-deformed SO(N) and USp(2N) N=4 supersymmetricYang-Mills theories - art. no. 106002

We generalize the results of Polchinski and Strassler regarding the N=1 pre serving mass deformation of N=4 SU(N) supersymmetric Yang-Mills (SYM) theor ies and its string theory dual to SO(N) and USp(2N) gauge groups. The strin g theory duals involve 5-branes wrapped on RP2. In order to match with the field theory classification of vacua, the 3-brane charge carried by such 5- branes must be shifted by a half, and this follows from a conjectured gener alization of results of Freed and Witten. Our results provide an elegant ph ysical picture for the classification of classically massive vacua in the m ass-deformed N=4 theories.