Casimir effect in (2 + 1)-dimensional noncommutative theories

We study the Dirichlet Casimir effect for a complex scalar field on two noncommutative spatial coordinates plus a commutative time. To that end, we introduce Dirichlet-like boundary conditions on a curve contained in the spatial plane, in such a way that the correct commutative limit can be reached. We evaluate the resulting Casimir energy for two different curves: (a) Two parallel lines separated by a distance L, and (b) a circle of radius R. In the first case, the resulting Casimir energy agrees exactly with the one corresponding to the commutative case, regardless of the values of L and of the noncommutativity scale θ, while for the latter the commutative behaviour is only recovered when R ≫√{ θ}. Outside of that regime, the dependence of the energy with R is substantially changed due to noncommutative corrections, becoming regular for R → 0.