Confinement and strings in MQCD

We study aspects of confinement in the M-theory fivebrane version of QCD (MQCD). We show heavy quarks are confined in hadrons (which take the form of membrane-fivebrane bound states) for N = 1 and softly broken N = 2 SU(N) MQCD. We explore and clarify the transition from the exotic physics of the latter to the standard physics of the former. In particular, the many strings and quark-antiquark mesons found in N = 2 field theory by Douglas and Shenker are reproduced. It is seen that in the N = 1 limit all but one such meson disappears while all of the strings survive. The strings of softly broken N = 2, N = 1, and even non-supersymmetric SU(N) MQCD have a common ratio for their tensions as a function of the amount of flux they carry. We also comment on the almost BPS properties of the Douglas-Shenker strings and discuss the brane picture for monopole confinement on N = 2 QCD Higgs branches. (C) 1998 Elsevier Science B.V.