HETEROTIC M(ATRIX) STRINGS AND THEIR INTERACTIONS

Following a recent proposal of Dijkgraaf, Verlinde and Verlinde, we sh ow that the M(atrix) theory compactified on S-1/Z(2) provides us with a non-perturbative description of the second-quantized light-cone hete rotic string. This so-called heterotic M(atrix) string theory is defin ed by a two-dimensional (8, 0) supersymmetric chiral gauge theory with gauge group SO(2N) in the large N limit. We argue that at the strong coupling fixed point the chiral gauge theory hows to a (8, 0) supercon formal field theory defined via the S-N symmetric product space orbifo ld. We show that the leading order correction to the strong coupling e xpansion corresponds to a unique irrelevant operator of scaling dimens ion three and describes the joining and splitting cubic interactions o f the light-cone heterotic string. We also speculate on a M(atrix) des cription of bosonic strings via dimensional reduction of d = 26 Yang-M ills theory. (C) 1997 Elsevier Science B.V.