HEP Lattice·hep-lat
9 papers—8 primary·1 cross-listed·reconstructed*
Massimo D'Elia🇮🇹 · Francesco Di Renzo🇮🇹 · Maria Paola Lombardo🇮🇹
We summarize our results on the phase diagram of QCD with emphasis on the high temperature regime. For the results are compatible with a free field behavior, while for this is not the case, clearly exposing the strongly interacting nature of QCD in this region
Falk Bruckmann🇳🇱 · Ernst-Michael Ilgenfritz🇩🇪
We compute low-lying eigenmodes of the gauge covariant Laplace operator on the lattice at finite temperature. For classical configurations we show how the lowest mode localizes the monopole constituents inside calorons and that it hops upon changing the boundary conditions. The latter effect we observe for thermalized backgrounds, too, analogously to what is known for fermion zero modes. We propose a new filter for equilibrium configurations which provides link variables as a truncated sum involving the Laplacian modes. This method not only reproduces classical structures, but also preserves the confining potential, even when only a few modes are used.
R. C. Brower🇺🇸 · H. Neff🇬🇧 · K. Orginos🇺🇸
We introduce a new domain wall operator that represents a full (real) Moebius transformation of a given non-chiral Dirac kernel. Shamir's and Borici's domain wall fermions are special cases of this new class. By tuning the parameters of the Moebius operator and by introducing a new Red/Black preconditioning, we are able to reduce the computational effort substantially.
Z. Fodor🇭🇺 · C. Hoelbling🇩🇪 · M. Mechtel🇩🇪 · K. Szabo🇩🇪
We perform an investigation of the static quark-quark-potential both in the confined and the deconfined phase. We discuss conceptual and technical problems and present first results of an exploratory numerical investigation.
Z. Fodor🇩🇪 · C. Guse🇩🇪 · S. Katz🇭🇺 · K. Szabo🇩🇪
The grand canonical potential for a static quark-antiquark pair at non-vanishing chemical potential was determined at several temperatures. The dynamical staggered simulations were carried out with 2+1 physical quarks along the Lines of Constant Physiscs (LCP).
Using orbifold techniques I construct the Schrodinger functional (SF) for a doublet of Wilson quarks with chirally rotated boundary conditions. This allows to perform checks of universality: for instance, the renormalized SF coupling constant, defined with either boundary conditions, must have a unique continuum limit. Similarly, SF correlation functions in twisted mass QCD and standard QCD can be defined such that they share a common continuum limit. An additional benefit of the new set-up consists in the observation that all the bulk O(a) counterterms to the action and composite operators become irrelevant in the chiral limit. This implies that (ratios of) SF renormalization constants can be automatically O(a) improved, up to the effect of unavoidable boundary counterterms. As a first application we calculate the running coupling for Nf=2 flavours in the SF-scheme to one-loop order of perturbation theory. Universality of the continuum limit is confirmed and the irrelevance of the Sheikholeslami-Wohlert term in the action is demonstrated explicitly
R. Frezzotti🇮🇹 · G.C. Rossi (Dipartimento di Fisica, Università di Roma Tor Vergata and INFN Sezione di Tor Vergata, Roma, ITALY)🇮🇹
In this review we discuss the general features of maximally twisted lattice QCD. In particular, we illustrate how automatic O(a) improvement can be achieved and how it is possible to set up a lattice regularization scheme where the problem of wrong chirality mixing (be it finite or infinite) affecting the computation of the matrix elements of the CP-conserving effective weak Hamiltonian is neatly avoided, while having at the same time a positive determinant even for non-degenerate quark pairs. The question of reducing the large cutoff effects that appear when the quark mass tends to zero as a consequence of parity and iso-spin breaking in the action is also addressed. It is shown that such dangerous lattice artifacts are strongly suppressed if the clover term is added to the action or, alternatively, the critical mass is chosen so as to enforce the restoration of parity.
L. Scorzato🇩🇪 · F. Farchioni🇩🇪 · P. Hofmann🇩🇪 · K. Jansen🇩🇪 · I. Montvay🇩🇪 · G. Munster🇩🇪 · M. Papinutto🇩🇪 · E. E. Scholz🇺🇸 · A. Shindler🇩🇪 · N. Ukita🇩🇪 · C. Urbach🇩🇪 · U. Wenger🇩🇪 · I. Wetzorke🇩🇪
By employing a twisted mass term, we compare recent results from lattice calculations of Nf=2 dynamical Wilson fermions with Wilson Chiral Perturbation Theory (WChPT). The final goal is to determine some combinations of Gasser-Leutwyler Low Energy Constants (LECs). A wide set of data with different lattice spacings (a ~ 0.2-0.12 fm), different gauge actions (Wilson plaquette, DBW2) and different quark masses (down to the lowest pion mass allowed by lattice artifacts and including negative quark masses) provide a strong check of the applicability of WChPT in this regime and the scaling behaviours in the continuum limit.
M. Caselle🇮🇹 · G. Delfino🇮🇹 · P. Grinza🇫🇷 · O. Jahn🇺🇸 · N. Magnoli🇮🇹
We discuss the two- and three-point correlators in the two-dimensional three-state Potts model in the high-temperature phase of the model. By using the form factor approach and perturbed conformal field theory methods we are able to describe both the large distance and the short distance behaviours of the correlators. We compare our predictions with a set of high precision Monte-Carlo simulations (performed on the triangular lattice realization of the model) finding a complete agreement in both regimes. In particular we use the two-point correlators to fix the various non-universal constants involved in the comparison (whose determination is one of the results of our analysis) and then use these constants to compare numerical results and theoretical predictions for the three-point correlator with no free parameter. Our results can be used to shed some light on the behaviour of the three-quark correlator in the confining phase of the (2+1)-dimensional SU(3) lattice gauge theory which is related by dimensional reduction to the three-spin correlator in the high-temperature phase of the three-state Potts model. The picture which emerges is that of a smooth crossover between a \Delta type law at short distances and a Y type law at large distances.
* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.