Noncommutative gauge theories and the cosmological constant

We discuss the issue of the cosmological constant in noncommutative nonsupersymmetric gauge theories. In particular, in orbifold field theories noncommutativity acts as a UV cutoff. We suggest that in these theories quantum corrections give rise to a vacuum energy ρ that is controlled by the noncommutativity parameter θ, $\rho \sim 1/{\theta }^2$ (only a soft logarithmic dependence on the Planck scale survives). We demonstrate our claim in a two-loop computation in field theory and by certain higher loop examples. Based on general expressions from string theory, we suggest that the vacuum energy is controlled by noncommutativity to all orders in perturbation theory.