ar X iv : h ep - l at / 9 70 91 16 v 1 2 5 Se p 19 97 1 Towards the Deconfinement Phase Transition in Hot Gauge Theories ∗ †

The phase structure of hot gauge theories with dynamical matter fields is reexamined in the canonical ensemble with respect to triality. We discuss properties of chromoelectric and chromomagnetic sectors of the theory and show whereas electric charges carrying a unit of Z(Nc) charge are screened at high temperatures via dynamical matter loops, this is not the case for the Z(Nc) magnetic flux. An order parameter is constructed to probe the realization of local Z(Nc) symmetry in the magnetic sector. We argue this order parameter may be used to detect the deconfinement phase transition which is defined in terms of the screening mechanism. Here we continue an investigation of the phase structure of hot gauge theories in the canonical ensemble with respect to triality [1]-[3]. Usually, the deconfinement phase transition is associated with the appearence of nonzero triality states in hot phase [4,5]. In particular Z(N c) gauge theories with Higgs fields have been precisely analyzed [5]. Since it was known that at zero temperature this system has two phases, a confining/screening phase and a deconfining one [6] separated by a critical line and since such a critical line was not found it has been concluded that at finite T the critical behaviour may not be present at all. Our motivation for what follows is I) it is not obvious a priori that " free triality states " indeed exist in deconfined phase and quite possible there might be a phase transition unrelated to the triality liberation but rather to different screening mechanisms of triality; II) the previous emphasis has been put on the realization of global Z(N c) symmetry. Localizing Z(N c) looks promising [7]. We are dealing with the canonical ensemble (CE) introduced in [1,2]. This ensemble reveals the following properties [3]: 1) In the low temperature phase every state has zero triality. In the deconfined phase the whole system possesses zero triality. Since all * Work supported by Bundesministerium für Wissenschaft, und Transport of Austria † presented by O. Borisenko Z(N c) noninvariant variables are projected out, the Polyakov loop (PL) itself has only little meaning in the CE and a single quark does not appear in the spectrum; 2) Metastable minima with unphysical properties are absent, all Z(N c) phases are degenerate; 3) Chiral symmetry is restored in all Z(N c) phases and at the same temperature [3]. Generalizing the A operator introduced in [7] to finite …