HEP Lattice·hep-lat

Fri·Oct 5, 2007Friday·October 5, 2007

12 papers—10 primary·2 cross-listed·reconstructed*

01*
Lattice Results for Vector Meson Couplings and Parton Distribution Amplitudes
D. Antonio🇬🇧 · P.A. Boyle🇬🇧 · M.A. Donnellan🇬🇧 · J. Flynn🇬🇧 · A. Juttner🇬🇧 · C. Maynard🇬🇧 · B. Pendleton🇬🇧 · C.T. Sachrajda🇬🇧 · R.Tweedie
We present results for the couplings of light vector mesons to vector and tensor currents and on the low moments of the light-cone distribution amplitudes of the pion and kaon. The calculations are performed on the RBC and UKQCD collaborations' ensembles generated with the Iwasaki gauge action and with 2+1 flavours of domain wall fermions. The (preliminary) results for the ratios of the couplings of the vector meson to the vector and tensor currents (f_V and f^T_V respectively) in the MSbar scheme at 2GeV are: f_\rho^T/f_\rho=0.681(20); f_{K^\ast}^T/f_{K^\ast}=0.712(11) and f_\phi^T/f_\phi=0.751(9). For the first moment of the kaon's distribution amplitude we find (in the same scheme and at the same scale) <xi>_K=0.029(2) and for the second moment <xi^2>_\pi=0.28(3) and <xi^2>_K=0.27(2).
hep-latPoS(2007)·44 citations
02*
Charm spectroscopy on dynamical 2+1 flavor domain wall fermion lattices with a relativistic heavy quark action
Min Li🇺🇸 · Huey-Wen Lin🇺🇸
We present a preliminary calculation of the charmonium spectrum using the dynamical 2+1 flavor $2 4^{3} \times 64$ domain wall fermion lattice configurations generated by the RBC and UKQCD collaborations. We use the relativistic heavy quark action with 3 parameters non-perturbatively determined by matching to experimental quantities. Chiral extrapolation is done on four light sea quark masses from 0.005 to 0.03, with $m_{s} = 0.04$ and $m_{r es} = 0.003$ . We can either predict meson masses assuming the lattice spacing is known from other methods, or calculate the lattice spacing using those quantities.
hep-latPoS(2007)·4 citations
03*
Light meson spectrum with $N_{f} = 2$ dynamical overlap fermions
J.Noaki🇯🇵 · S.Aoki🇯🇵 · H.Fukaya🇯🇵 · S.Hashimoto🇯🇵 · T.Kaneko🇯🇵 · H.Matsufuru🇯🇵 · T.Onogi🇯🇵 · E.Shintani🇯🇵 · N.Yamada🇯🇵
We present numerical simulation of QCD with two dynamical quark flavors described by the overlap fermion action on a $1 6^{3} \times 32 \times (0.12 fm)^{4}$ lattice. We calculate pseudo-scalar masses and decay constants and investigate their chiral properties. We test the consistency of our data with the two-loop chiral perturbation theory predictions, which should also be valid at finite lattice spacings because of the exact chiral symmetry, including the finite size effects.
hep-latPoS(2007)·32 citations
04*
Thermodynamics and heavy-quark free energies at finite temperature and density with two flavors of improved Wilson quarks
Y. Maezawa🇯🇵 · S. Aoki🇯🇵 · S. Ejiri🇺🇸 · T. Hatsuda🇯🇵 · N. Ishii🇯🇵 · K. Kanaya🇯🇵 · N. Ukita🇯🇵 · T. Umeda🇯🇵
Thermodynamics of two-flavor QCD at finite temperature and density is studied on a $1 6^{3} \times 4$ lattice, using a renormalization group improved gauge action and the clover improved Wilson quark action. In the simulations along lines of constant $m_{PS} / m_{V}$ , we calculate the Taylor expansion coefficients of the heavy-quark free energy with respect to the quark chemical potential ( $μ_{q}$ ) up to the second order. By comparing the expansion coefficients of the free energies between quark( $Q$ )and antiquark( $Q ˉ$ ), and between $Q$ and $Q$ , we find a characteristic difference at finite $μ_{q}$ due to the first order coefficient of the Taylor expansion. We also calculate the quark number and isospin susceptibilities, and find that the second order coefficient of the quark number susceptibility shows enhancement around the pseudo-critical temperature.
hep-latPoS(2007)·8 citations
05*
Screening masses of mesons in 2+1 flavour QCD
RBC-Bielefeld Collaboration: Swagato Mukherjee🇩🇪
We present results for screening masses of light and strange mesons in 2+1 flavour QCD using improved (p4fat3) staggered fermions on 6x24^3 lattices. We have studied the screening masses of scalar, pseudo-scalar, vector and axial-vector mesons along the line of constant physics, determined by a pion mass ~220 MeV and a kaon mass ~500 MeV. In order to investigate the cut-off and volume dependencies we have also performed studies of the meson screening correlators in the non-interacting theory using the p4 and the standard staggered discretizations.
hep-lathep-phnucl-thPoS(2007)·6 citations
06*
Renormalisation of quark bilinears with Nf=2 Wilson fermions and tree-level improved gauge action
P. Dimopoulos🇮🇹 · R. Frezzotti🇮🇹 · G. Herdoiza🇮🇹 · V. Lubicz🇮🇹 · M. Papinutto🇨🇭 · S. Simula🇮🇹 · A. Vladikas🇮🇹
We present results for the renormalisation constants of bilinear quark operators, using the Nf=2 twisted mass Wilson action at maximal twist (which guarantees automatic O(a) improvement) and the tree-level Symanzik improved gauge action. The scale-independent renormalisation constants are computed with a new method, which makes use of both standard twisted mass and Osterwalder-Seiler fermions. Moreover, the results from an RI-MOM calculation are presented for both scale independent and scale dependent renormalisation constants.
hep-latPoS(2007)·29 citations
07*
Hard hadron spectroscopy
Craig McNeile🇬🇧
I review lattice QCD calculations that compute the masses of the flavour singlet pseudoscalar mesons. I describe the progress in computing the mass spectrum of light 0++ mesons using lattice QCD. I also compare the results for basic quantities such as fpi and mrho, from various different formalisms of lattice QCD. I discuss the physical value of r0.
hep-latPoS(2007)·34 citations
08*
Perturbative determination of $c_{S W}$ with Symanzik improved gauge action and stout smearing
R. Horsley🇬🇧 · H. Perlt🇩🇪 · P.E.L. Rakow🇬🇧 · G. Schierholz🇩🇪 · A. Schiller🇩🇪
We determine the improvement factor $c_{S W}$ in one-loop lattice perturbation theory for the plaquette and Symanzik improved gauge actions. The fermionic action is $O (a)$ clover improved with one-time stout smearing. $c_{S W}$ is derived from the one-loop correction to the quark-quark-gluon vertex in the off-shell regime. We give a first numerical value for the one-loop contribution to the non gauge-invariant improvement coefficient $c_{N G I}$ for the quark field using the plaquette action. A discussion of mean field improvement is included.
hep-latPoS(2007)·5 citations
09*
Schwinger model simulations with dynamical overlap fermions
Wolfgang Bietenholz🇩🇪 · Stanislav Shcheredin🇩🇪 · Jan Volkholz🇩🇪
We present simulation results for the 2-flavour Schwinger model with dynamical overlap fermions. In particular we apply the overlap hypercube operator at seven light fermion masses. In each case we collect sizable statistics in the topological sectors 0 and 1. Since the chiral condensate Sigma vanishes in the chiral limit, we observe densities for the microscopic Dirac spectrum, which have not been addressed yet by Random Matrix Theory (RMT). Nevertheless, by confronting the averages of the lowest eigenvalues in different topological sectors with chiral RMT in unitary ensemble we obtain -- for the very light fermion masses -- values for Sigma that follow closely the analytical predictions in the continuum.
hep-latPoS(2007)·3 citations
10*
The nature of the finite temperature QCD transition as a function of the quark masses
G. Endrodi🇭🇺 · Z. Fodor🇩🇪 · S. D. Katz🇭🇺 · K. K. Szabo🇩🇪
The finite temperature QCD transition for physical quark masses is a crossover. For smaller quark masses a first-order phase transition is expected. Using Symanzik improved gauge and stout improved fermion action for 2+1 flavour staggered QCD we give estimates/bounds for the phase line separating the first-order region from the crossover one. The calculations are carried out on two different lattice spacings. Our conclusion for the critical mass is $m_{0} ≲ 0.07 \cdot m_{p h y s}$ for $N_{T} = 4$ and $m_{0} ≲ 0.12 \cdot m_{p h y s}$ for $N_{T} = 6$ lattices.
hep-latPoS(2007)·68 citations
11*
QCD symmetries in excited hadrons
L. Ya. Glozman🇦🇹
Recent developments for chiral and $U (1)_{A}$ restorations in excited hadrons are reviewed. We emphasize predictions of the chiral symmetry restoration scenario for axial charges and couplings to Goldstone bosons. Using very general chiral symmetry arguments it is shown that strict chiral restoration in a given excited nucleon forbids its decay into the $N π$ channel. We confront this prediction with the $N^{*} N π$ coupling constants extracted from the decay widths and observe a 100 % correlation of these data with the spectroscopic parity doublet patterns. These results suggest that the lowest approximate chiral parity doublet is the $N (1440) - N (1535)$ pair. In the meson sector we discuss predictions of the chiral symmetry restoration for still missing states and a signature of the higher symmetry observed in new $p ˉ p$ data. We conclude with the exactly solvable chirally symmetric and confining model that can be considered as a generalization of the 1+1 dimensional 't Hooft model to 4 dimensions. Complete spectra of $q ˉ q$ mesons demonstrate a fast chiral restoration with increasing $J$ and a slow one with increasing $n$ .
↳ hep-phhep-exhep-lathep-th+1eConf(2007)·4 citations
12*
Lower dimensional Yang-Mills theory as a laboratory to study the infrared regime
Reinhard Alkofer🇦🇹 · Christian S. Fischer🇩🇪 · Markus Q. Huber🇦🇹 · Kai Schwenzer🇦🇹
Lattice studies of the infrared regime of gauge theories are complicated by the required extensive limits, the performed gauge fixing and the demand for high statistics. Using a general power counting scheme for the infrared limit of Landau gauge SU(N) Yang-Mills theory in arbitrary dimensions we show that the infrared behavior of Greens functions is both qualitatively and quantitatively similar in two, three and four spacetime dimensions. Therefore, lower dimensional lattice simulations can serve as a simplified laboratory to analyze the presently applied approximations and to obtain first results for higher correlation functions.
↳ hep-phhep-latPoS(2007)·5 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.