Speaker
Description
The effective potential of the Polyakov loop is investigated within the Hamiltonian approach to QCD in Coulomb gauge where finite temperature $T$ is introduced by compactifying one space direction. We briefly review this approach and extend earlier work in the Yang-Mills sector by including dynamical quarks. In a first approximation, we follow the usual practice in functional approaches and include only one-loop contributions, with the finite temperature propagators replaced by their $T=0$ counter parts. It is found that this gives a poor description of the phase transition, in particular for the case of full QCD with $N_f = 3$ light flavours. The physical reasons for this unexpected result are discussed, and pinned down to a relative weakness of gluon confinement compared to the deconfining tendency of the quarks. We attempt to overcome this issue by including the relevant gluon contributions from the two-loop terms to the energy. We find that the two-loop corrections have indeed a tendency to strengthen the gluon confinement and weaken the unphysical effects in the confining phase, while slightly increasing the (pseudo-)critical temperature $T^\ast$ at the same time. To fully suppress artifacts in the confining phase, we must tune the parameters to rather large values, increasing the critical temperature to $T^\ast \approx340\,\mathrm{MeV}$ for $G=SU(2)$.
