Free energy of an SU(2) monopole-antimonopole pair - art. no. 034506

We present a high-statistic numerical study of the free energy of a monopol e-antimonopole pair in pure SU(2) theory. We find that the monopole-antimon opole interaction potential exhibits a screened behavior, as one would expe ct in the presence of a monopole condensate. Screening occurs both in the l ow-temperature, confining phase of the theory, and in the high-temperature deconfined phase, with no evidence of a discontinuity of the screening mass across the transition. The mass of the object responsible for the screenin g at low temperature is approximately twice the established value for the l ightest glueball, indicating a prevalent coupling to glueball excitations. At high temperature, the screening mass increases. We contrast the behavior of the quantum system with that of the corresponding classical system, whe re the monopole-antimonopole potential is of the Coulomb type.