1+1 dimensional NCOS and its U(N) gauge theory dual

We study some aspects of open string theories on D-branes with critical ele ctric fields. We show that the massless open string modes that move in the direction of the electric field decouple. In the 1+1 dimensional case the d ual theory is U(N) SYM with electric Aux, and the decoupling of massless op en strings is dual to the decoupling of the U(1) degrees of freedom. We als o show that, if the direction along the electric field is compact, then the re are finite energy winding closed string modes. They are dual to Higgs br anch excitations of the SYM theory, and their energetics works accordingly. These properties provide new non-trivial evidence for the duality.