Kostas Orginos

QCD spectrum with three quark flavors

We present results from a lattice hadron spectrum calculation using three flavors of dynamical quarks -- two light and one strange -- and quenched simulations for comparison. These simulations were done using a one-loop Symanzik improved gauge action and an improved Kogut-Susskind quark action. The lattice spacings, and hence also the physical volumes, were tuned to be the same in all the runs to better expose differences due to flavor number. Lattice spacings were tuned using the static quark potential, so as a by-product we obtain updated results for the effect of sea quarks on the static quark potential. We find indications that the full QCD meson spectrum is in better agreement with experiment than the quenched spectrum. For the 0{sup ++} (a{sub 0}) meson we see a coupling to two pseudoscalar mesons, or a meson decay on the lattice.

Nucleon Generalized Parton Distributions from Full Lattice QCD

We present a comprehensive study of the lowest moments of nucleon generalized parton distributions in N{sub f}=2+1 lattice QCD using domain-wall valence quarks and improved staggered sea quarks. Our investigation includes helicity dependent and independent generalized parton distributions for pion masses as low as 350 MeV and volumes as large as (3.5 fm){sup 3}, for a lattice spacing of 0.124 fm. We use perturbative renormalization at one-loop level with an improvement based on the nonperturbative renormalization factor for the axial vector current, and only connected diagrams are included in the isosinglet channel.

Evidence for a bound H dibaryon from lattice QCD.

We present evidence for the existence of a bound H dibaryon, an I=0, J=0, s=-2 state with valence quark structure uuddss, at a pion mass of m(π)∼389  MeV. Using the results of lattice QCD calculations performed on four ensembles of anisotropic clover gauge-field configurations, with spatial extents of L∼2.0, 2.5, 3.0, and 3.9 fm at a spatial lattice spacing of b(s)∼0.123  fm, we find an H dibaryon bound by B(∞)(H)=16.6±2.1±4.6  MeV at a pion mass of m(π)∼389  MeV.

Nucleon structure from mixed action calculations using 2+1 flavors of asqtad sea and domain wall valence fermions

We present high statistics results for the structure of the nucleon from a mixed-action calculation using 2+1 flavors of asqtad sea and domain-wall valence fermions. We perform extrapolations of our data based on different chiral effective field theory schemes and compare our results with available information from phenomenology. We discuss vector and axial form factors of the nucleon, moments of generalized parton distributions, including moments of forward parton distributions, and implications for the decomposition of the nucleon spin.

Deconfining Phase Transition as a Matrix Model of Renormalized Polyakov Loops

We discuss how to extract renormalized loops from bare Polyakov loops in

Light hadron spectroscopy using domain wall valence quarks on an Asqtad sea

\mathrm{SU}(N)

Hyperon–nucleon scattering from fully-dynamical lattice QCD

lattice gauge theories at nonzero temperature. Single loops in an irreducible representation are multiplicatively renormalized, without mixing, through mass renormalization. The values of renormalized loops in the four lowest representations of

Testing improved actions for dynamical Kogut-Susskind quarks

\mathrm{SU}(3)

Light Nuclei and Hypernuclei from Quantum Chromodynamics in the Limit of SU(3) Flavor Symmetry

were measured numerically on small, coarse lattices. We find that in magnitude, condensates for the sextet and octet loops are approximately the square of the triplet loop. This agrees with a large N expansion, where factorization implies that the expectation values of loops in adjoint and higher representations are powers of fundamental and antifundamental loops. The corrections to the large N relations at three colors are greatest for the sextet loop,

I=2 pi-pi Scattering from Fully-Dynamical Mixed-Action Lattice QCD

\ensuremath{\sim}1/N,