Electric and magnetic Landau-gauge gluon propagators in finite-temperature SU(2) gauge theory

Abstract

We perform lattice simulations in pure-SU(2) Yang-Mills theory to investigate how the infrared behavior of electric and magnetic gluon propagators in Landau gauge is affected by temperature. We consider the largest lattices to date, in an attempt to kee p systematic errors under control. Electric and magnetic screening masses are calculated through an Ansatz from the zero-temperature case, based on complex-conjugate poles for the momentum-space propagators. As recently reported in [1], we find good fits to the proposed form at all tempe ratures considered, with different ratios of real to imaginary part of the pole masses for the lon gitudinal (electric) and transverse (magnetic) propagators. The behavior of the magnetic propagator DT(p) is in agreement with the dimensional-reduction picture, showing infrared suppression (with a turnover in momentum) and violation of spectral positivity at all nonzero temperatur es considered. The longitudinal propagator DL(p) appears to reach a plateau at small momenta and is subject to severe finite- Nt effects around the critical temperature Tc. As a consequence, only lattices with temporal extent Nt > 8 seem to be free from systematic errors. After these errors are removed, the infrared-plateau value is considerably reduced around the transition and the sharp peak observed previously for this quantity at Tc is no longer present. The resulting infrared behavior for DL(p) at Tc is essentially the same as for 0.5Tc. An investigation of the temperature range between 0.5Tc and Tc reveals that a less pronounced (finite) peak may occur at smaller temperat ures, e.g. T ≈ 0.9Tc.