A Matrix String Interpretation of the Large N Loop Equation

The existence two S-dual descriptions of (N,1) string bound states suggests that the strong coupling behaviour of electric flux lines in large N 2D SYM theory has a dual description in terms of weakly coupled IIB string theory. In support of this identification, we propose a dual interpretation of the SYM loop equation as a perturbative string Ward identity, expressing the conformal invariance of the corresponding boundary interaction. This correspondence can be viewed as a weak coupling check of the matrix string conjecture.