Twisted mass QCD at finite temperature

We discuss the use of Wilson fermions with twisted mass for simulations of QCD thermodynamics. As a prerequisite for a future analysis of the finite-temperature transition making use of automatic O(a) improvement, we investigate the phase structure in the space spanned by the hopping parameter k , the coupling b , and the twisted mass parameter m. We present results for Nf = 2 degenerate quarks on a 163×8 lattice, for which we investigate the possibility of an Aoki phase existing at strong coupling and vanishing m, as well as of a thermal phase transition at moderate gauge couplings and non-vanishing m

Vacuum structure and string tension in Yang-Mills dimeron ensembles

We numerically simulate ensembles of SU(2) Yang-Mills dimeron solutions with a statistical weight determined by the classical action and perform a comprehensive analysis of their properties. In particular, we examine the extent to which these ensembles capture topological and confinement properties of the Yang-Mills vacuum. This further allows us to test the classic picture of meron-induced quark confinement as triggered by dimeron dissociation. At small bare couplings, spacial, topological-charge and color correlations among the dimerons generate a short-range order which screens topological charges. With increasing coupling this order weakens rapidly, however, in part because the dimerons gradually dissociate into their meron constituents. Monitoring confinement properties by evaluating Wilson-loop expectation values, we find the growing disorder due to these progressively liberated merons to generate a finite and (with the coupling) increasing string tension. The short-distance behavior of the static quark-antiquark potential, on the other hand, is dominated by small, "instanton-like" dimerons. String tension, action density and topological susceptibility of the dimeron ensembles in the physical coupling region turn out to be of the order of standard values. Hence the above results demonstrate without reliance on weak-coupling or low-density approximations that the dissociating dimeron component in the Yang-Mills vacuum can indeed produce a meron-populated confining phase. The density of coexisting, hardly dissociated and thus instanton-like dimerons seems to remain large enough, on the other hand, to reproduce much of the additional phenomenology successfully accounted for by non-confining instanton vacuum models. Hence dimeron ensembles should provide an efficient basis for a rather complete description of the Yang-Mills vacuum.Comment: 36 pages, 17 figure

Informations- und Kommunikationszentrum in Adlershof

Thesen zum Workshop „Die Bibliothek der Zukunft, Planungen zu einem Informations- und Kommunikationszentrum in Adlershof“, 11. Oktober 1995 in der Humboldt-Universität zu Berlin

On the suppression of the topological susceptibility by dynamical quarks in SU(2) lattice gauge theory

Dittes FM, Ilgenfritz E-M, Jozefini B, Müller-Preußker M. On the suppression of the topological susceptibility by dynamical quarks in SU(2) lattice gauge theory. Physics Letters B. 1989;229(1-2):89-92

Thermal transition temperature from twisted mass QCD

Burger F, Kirchner M, Müller-Preußker M, et al. Thermal transition temperature from twisted mass QCD. Presented at the The XXVIII. International Symposium on Lattice Field Theory, Villasimius, Sardinia Italy

Twisted mass QCD at finite temperature.

We discuss the use of Wilson fermions with twisted mass for simulations of QCD thermodynamics. As a prerequisite for a future analysis of the finite-temperature transition making use of automatic O(a) improvement, we investigate the phase structure in the space spanned by the hopping parameter kappa, the coupling beta, and the twisted mass parameter mu. We present results for N_f=2 degenerate quarks on a 16^3x8 lattice, for which we investigate the possibility of an Aoki phase existing at strong coupling and vanishing mu, as well as of a thermal phase transition at moderate gauge couplings and non-vanishing mu.Comment: 7 pages, 8 figures, poster presented at the XXV International Symposium on Lattice Field Theory, July 30 - August 4, 2007, Regensburg, German