Fri·Nov 4, 2005Friday·November 4, 2005

1. 01*

   Scaling behavior of quark propagator in full QCD

   Maria B. Parappilly🇦🇺 · Patrick O. Bowman🇺🇸 · Urs M. Heller🇺🇸 · Derek B . Leinweber🇦🇺 · Anthony G. Williams🇦🇺 · J.B Zhang🇦🇺

   We study the scaling behavior of the quark propagator on two lattices with similar physical volume in Landau gauge with 2+1 flavors of dynamical quarks in order to test whether we are close to the continuum limit for these lattices. We use configurations generated with an improved staggered (``Asqtad'') action by the MILC collaboration. The calculations are performed on $28^3\times 96$ lattices with lattice spacing $a=0.09$ fm and on $20^3\times 64$ lattices with lattice spacing $a=0.12$ fm. We calculate the quark mass function, $M(q^2)$, and the wave-function renormalization function, $Z(q^2)$, for a variety of bare quark masses. Comparing the behavior of these functions on the two sets of lattices we find that both $Z(q^2)$ and $M(q^2)$ show little sensitivity to the ultraviolet cutoff.

   hep-latPRD(2006)·129 citations
2. 02*

   QCD string from D0 branes

   M. Billo🇮🇹 · M. Caselle🇮🇹 · M. Hasenbusch🇮🇹 · M. Panero🇮🇪

   We report the results of a set of high precision simulations performed in the 3d gauge Ising model. We evaluated the interquark potential and the first few energy levels and compared them with the predictions obtained with the effective Nambu-Goto string and with the free bosonic string. The data are precise enough to unambiguously distinguish between the free string predictions and those obtained using the N-G effective string. At large distances we find a remarkable agreement between Monte Carlo data and N-G predictions for the first excited energy level, while the free string picture is definitely excluded. As the interquark distance is decreased (and/or the finite temperature becomes higher) the Monte Carlo results show larger and larger deviations both from the N-G and from the free string predictions. In order to better understand this behaviour we re-derived the effective Nambu-Goto theory result for the Polyakov loop correlator using a covariant quantization. We chose as boundary conditions those of an open string attached to two D0-branes at spatial distance $R$, in a target space with compact euclidean time. Obviously our treatment is fully consistent only in $d=26$. The extension to generic $d$ requires taking into account the Liouville mode of Polyakov's formulation. The analogy with the standard light cone calculation suggests that the contribution due to the Liouville field can be neglected for large $R$. At shorter scales, the Liouville mode cannot be neglected and its contribution to the interquark potential might be the source of the discrepancies with respect to the effective N-G results that we observe in our Monte Carlo simulations.

   hep-latPoS(2006)·4 citations
3. 03*

   Soffer Bound and Transverse Spin Densities from Lattice QCD

   M. Diehl🇩🇪 · M. Gockeler🇩🇪 · Ph. Hagler🇩🇪 · R. Horsley🇬🇧 · D. Pleiter🇩🇪 · P.E.L. Rakow🇬🇧 · A. Schafer🇩🇪 · G. Schierholz🇩🇪 · J.M. Zanotti🇬🇧

   Generalized transversity distributions encode essential information on the internal structure of hadrons related to transversely polarized quarks. Lattice QCD allows us to compute the lowest moments of these tensor generalized parton distributions. In this talk, we discuss a first lattice study of the Soffer bound and show preliminary results for transverse spin densities of quarks in the nucleon.

   ↳ hep-phhep-lat21 citations
4. 04*

   Lattice computation of the strange quark mass in QCD

   Francesco Knechtli🇨🇭

   We present a determination of the strange quark mass using lattice QCD. Particular focus is put on the definition and renormalization of the mass. The latter is done non-perturbatively, using a recursive finite-size scaling technique. The hadronic regime of QCD, where the kaon mass is used as input of the calculation, is connected with the perturbative regime, where the strange quark mass can be translated into the MSbar scheme. A summary plot of the present lattice computations using dynamical (sea) quarks is included.

   ↳ hep-phhep-latActa Phys.Polon.B(2005)·9 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.