Casimir effect in ( 2 + 1 )-dimensional Yang-Mills theory as a probe of the magnetic mass

We consider the Casimir effect in a gauge-invariant Hamiltonian formulation of non-Abelian gauge theories in (2+1) dimensions, for an arbitrary gauge group. We show that the result is in good agreement with recent lattice simulations. We also argue that the Casimir effect may be viewed as a good probe of magnetic screening effects in (3+1)-dimensional gauge theories at high temperatures.