Fri·Nov 9, 2007Friday·November 9, 2007

1. 01*

   Towards 4-loop NSPT result for a 3-dimensional condensate-contribution to hot QCD pressure

   C. Torrero🇩🇪 · M. Laine🇩🇪 · Y. Schroder (Bielefeld U.)🇩🇪 · F. Di Renzo (Parma U. & INFN, Parma)🇮🇹 · V. Miccio (CERN)🇨🇭

   Thanks to dimensional reduction, the contributions to the hot QCD pressure coming from so-called soft modes can be studied via an effective three-dimensional theory named Electrostatic QCD (spatial Yang-Mills fields plus an adjoint Higgs scalar). The poor convergence of the perturbative series within EQCD suggests to perform lattice measurements of some of the associated gluon condensates. These turn out, however, to be plagued by large discretization artifacts. We discuss how Numerical Stochastic Perturbation Theory can be exploited to determine the full lattice spacing dependence of one of these condensates up to 4-loop order, and sharpen our tools on a concrete 2-loop example.

   hep-latPoS(2007)·4 citations
2. 02*

   Progress in kaon physics on the lattice

   Andreas Juttner🇬🇧

   CKM-unitarity, direct and indirect CP-violation and the \Delta I=1/2 rule in full lattice QCD are the focus of this talk. To this end I will discuss and compare recent lattice results for leptonic, semi-leptonic and non-leptonic decays of the kaon and neutral kaon mixing and I will motivate current best estimates f_K/f_\pi=1.198(10), f_+^{K\pi}(0)=0.964(5) and \hat{B}_K=0.720(39). Moreover new theoretical advances that will improve the quality of these computations in the future will be discussed.

   hep-lathep-phPoS(2007)·25 citations
3. 03*

   Magnetic monopoles in the high temperature phase of Yang-Mills theories

   Alessio D'Alessandro🇮🇹 · Massimo D'Elia🇮🇹

   We investigate the properties of thermal abelian magnetic monopoles in the high temperature phase of Yang--Mills theories, following a recent proposal for their identification on lattice configurations. The study is done for SU(2) pure gauge theory, for temperatures going up to about 10 times the deconfining temperature and using the Maximal Abelian gauge to perform the abelian projection. We find that the monopole density has a well defined continuum limit. Its temperature dependence disagrees with a free particle gas prediction and is instead well described by a $T^3/(\log (T/\Lambda ){)}^{\alpha }$ behaviour in all the explored range, with $\alpha \sim 2$ and $\Lambda \sim 100$ MeV. Also the study of spatial correlations of thermal monopoles shows the presence of non-trivial interactions among them. Finally, we discuss the gauge dependence of our results, showing that it is significant and that, even within the Maximal Abelian gauge, Gribov copy effects are important.

   hep-lathep-phNPB(2008)·82 citations
4. 04*

   Holographic glueball structure

   Hilmar Forkel🇧🇷

   We derive and systematically analyze scalar glueball correlation functions in both the hard-wall and dilaton soft-wall approximations to holographic QCD. The dynamical content of the holographic correlators is uncovered by examining their spectral density and by relating them to the operator product expansion, a dilatational low-energy theorem and a recently suggested two-dimensional power correction associated with the short-distance behavior of the heavy-quark potential. This approach provides holographic estimates for the three lowest-dimensional gluon condensates or alternatively their Wilson coefficients, the two leading moments of the instanton size distribution in the QCD vacuum and an effective UV gluon mass. A remarkable complementarity between the nonperturbative physics of the hard- and soft-wall correlators emerges, and their ability to describe detailed QCD results can be assessed quantitatively. We further provide the first holographic estimates for the decay constants of the 0++ glueball and its excitations. The hard-wall background turns out to encode more of the relevant QCD physics, and its prediction f ~ 0.8-0.9 GeV for the phenomenologically important ground state decay constant agrees inside errors with recent QCD sum rule and lattice results.

   ↳ hep-phhep-lathep-thPRD(2008)·100 citations

* 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.