Geometric transition, large N dualities and MQCD dynamics

We study Vafa's geometric transition from a brane setup in M-theory. In thi s transition D5 branes wrapped on Pl cycles of a resolved conifold disappea r and are replaced by fluxes on a deformed conifold. In the limit of small sized P-1, we describe this mechanism as a transition from curved M5 branes to plane M5 branes which replaces SU(N) MQCD by U(1) theories on the bulk. This agrees with the results expected from the geometric transition. We al so discuss the reduction to ten dimensions and a brane creation mechanism i n the presence of fluxes. (C) 2001 Elsevier Science B.V. All rights reserve d.