Large-N limit of non-commutative gauge theories

Using the correspondence between gauge theories and string theory in curved backgrounds, we investigate aspects of the large-N limit of non-commutative gauge theories by considering gravity solutions with B fields. We argue that the total number of physical degrees of freedom at any given scale coincides with the commutative case. We then compute a two-point correlation function involving momentum components in the directions of the B-field. In the infrared regime it reproduces the usual behavior of the commutative gauge theory (i.e. of the form k(4) log k(2)). In the UV regime, we find that the two-point function decays exponentially with the momentum. A calculation of Wilson lines suggests that strings cannot be localized near the boundary. We also find string configurations that are localized in a finite region of the radial direction. These are worldsheet instantons.