Composite reweighting SU(2) QCD at Finite Temperature

The Glasgow reweighting method is evaluated for SU(2) lattice gauge theory at nonzero \mu and finite T. We establish that the ' overlap problem' of SU(3) measurements, in which the transition points determined from thermodynamic observables have an unphysical dependence on the value of \mu used in the reweighting persists for SU(2). By combining the information from different lattice ensembles we alleviate sampling bias in the fugacity expansion, and identify the Lee-Yang zeros associated with the transition to a high density phase that can plausibly be associated with diquark condensation. We also confirm the existence of a line of first order transitions above a critical point in the T-\mu plane previously identified by effective chiral lagrangian calculations.Comment: 8 pages, 7 figure

Covariant gauges at finite temperature

A prescription is presented for real-time finite-temperature perturbation theory in covariant gauges, in which only the two physical degrees of freedom of the gauge-field propagator acquire thermal parts. The propagators for the unphysical degrees of freedom of the gauge field, and for the Faddeev-Popov ghost field, are independent of temperature. This prescription is applied to the calculation of the one-loop gluon self-energy and the two-loop interaction pressure, and is found to be simpler to use than the conventional one.Comment: 11 pages plus pictex figures (the leading-temperature contributions given in sect 3.1 were incomplete) CERN-TH-6491/92, published in Nucl Phys B383 (1992) 60