5 DIMENSIONAL SUSY FIELD-THEORIES, NONTRIVIAL FIXED-POINTS AND STRINGDYNAMICS

We study (non-renormalizable) five dimensional supersymmetric field th eories. The theories are parametrized by quark masses and a gauge coup ling. We derive the metric on the Coulomb branch exactly. We use strin gy considerations to learn about new non-trivial interacting field the ories with exceptional global symmetry E(n) (E(8), E(7), E(6), E(5) = Spin(10), E(4) = SU(5), E(3) = SU(3) x SU(2), E(2) = SU(2) x U(1) and E(1) = SU(2)). Their Coulomb branch is R(+) and their Higgs branch is isomorphic to the moduli space of E, instantons. One of the relevant o perators of these theories leads to a flow to SU(2) gauge theories wit h N-f = n - 1 flavors. In terms of these SU(2) IR theories this releva nt parameter is the inverse gauge coupling constant. Other relevant op erators (which become quark masses after flowing to the SU(2) theories ) lead to flows between them. Upon further compactifications to four a nd three dimensions we find new fixed points with exceptional symmetri es.