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It has been suggested to use the production of Lambda hyperons for investigating the nucleon spin structure. The viability of this idea depends crucially on the spin structure of the Lambda. Using nonperturbatively O(a) improved Wilson…

High Energy Physics - Lattice · Physics 2008-11-26 M. Göckeler , R. Horsley , D. Pleiter , P. E. L. Rakow , S. Schaefer , A. Schäfer , G. Schierholz

I report on first results of the ETMC obtained simulating lattice QCD with two degenerate flavours of Wilson twisted mass fermions, for which physical observables are automatically O(a) improved. Recent improvements of the HMC algorithm…

High Energy Physics - Phenomenology · Physics 2007-05-23 Andrea Shindler , ETM Collaboration

We give a brief sketch of lattice structure function calculations and review previous results for the axial coupling $g_A$. We outline a new technique for treating fermions on the lattice that preserves chiral symmetry, domain wall…

High Energy Physics - Lattice · Physics 2007-05-23 T. Blum , S. Sasaki

We explore sea quark effects in the light hadron mass spectrum in a simulation of two-flavor QCD using the nonperturbatively O(a)-improved Wilson fermion action. In order to identify finite-size effects, light meson masses are measured on…

We report on recent results of the QCDSF/UKQCD Collaboration on investigations of baryon structure using configurations generated with N_f=2+1 dynamical flavours of O(a) improved Wilson fermions. With the strange quark mass as an additional…

High Energy Physics - Lattice · Physics 2011-03-22 M. Göckeler , Ph. Hägler , R. Horsley , Y. Nakamura , D. Pleiter , P. E. L. Rakow , A. Schäfer , G. Schierholz , H. Stüben , F. Winter , J. M. Zanotti

We analyze the chiral behavior of the hadron spectrum obtained with quenched Wilson fermions on 170 $32^3 \times 64$ lattices at $\beta = 6.0$. We calculate masses of hadrons composed of both degenerate and non-degenerate quarks. We reduce…

High Energy Physics - Lattice · Physics 2007-05-23 Tanmoy Bhattacharya , Rajan Gupta , Stephen Sharpe

We present a study of ${\cal O}(2000)$ (quenched) lattice configurations from the APE collaboration, for $6.0\le\beta\le 6.4$ using both the Wilson and the SW-Clover fermion action. We determine the light hadronic spectrum and meson decay…

High Energy Physics - Lattice · Physics 2016-09-01 C. R. Allton , V. Gimenez , L. Giusti , F. Rapuano

We present results from a simulation of quenched overlap fermions with L\"uscher-Weisz gauge field action on lattices up to $24^3 48$ and for pion masses down to $\approx 250$ MeV. Among the quantities we study are the pion, rho and nucleon…

High Energy Physics - Lattice · Physics 2008-11-26 D. Galletly , M. Gürtler , R. Horsley , H. Perlt , P. E. L. Rakow , G. Schierholz , A. Schiller , T. Streuer

We present results from simulations using 2 flavours of O(a)-improved Wilson quarks whose masses are about 1/3 of the physical strange quark mass. We present new data on the mass of the singlet pseudoscalar meson and evidence of the onset…

High Energy Physics - Lattice · Physics 2008-11-26 CR Allton , A Hart , D Hepburn , AC Irving , B Joo , C McNeile , C Michael , SV Wright

We present first results for light hadron masses, quark masses and decay constants in the continuum limit using O(a) improved fermions at three different values of the gauge coupling \beta.

High Energy Physics - Lattice · Physics 2008-11-26 M. Goeckeler , R. Horsley , V. Linke , D. Pleiter , P. E. L. Rakow , G. Schierholz , A. Schiller , P. Stephenson , H. Stueben

Within the framework of quenched lattice QCD and using O(a) improved Wilson fermions and non-perturbative renormalisation, a high statistics computation of low moments of the unpolarised nucleon structure functions is given. Particular…

High Energy Physics - Phenomenology · Physics 2008-11-26 M. Göckeler , R. Horsley , D. Pleiter , P. E. L. Rakow , G. Schierholz

The electromagnetic form factors provide important insight into the internal structure of the nucleon and continue to be of major interest for experiment and phenomenology. For an intermediate range of momenta the form factors can be…

We report our progress in simulating Neuberger valence fermions on N_f=2 Wilson O(a)-improved sea quarks. We compute correlators with valence quark masses both in the p- and in the epsilon-regime, and we match the results with the…

High Energy Physics - Lattice · Physics 2011-10-06 Fabio Bernardoni , Nicolas Garron , Pilar Hernandez , Silvia Necco , Carlos Pena

We present results on the spin and quark content of the nucleon using $N_f=2$ twisted mass clover-improved fermion simulations with a pion mass close to its physical value. We use recently developed methods to obtain accurate results for…

High Energy Physics - Lattice · Physics 2016-11-29 C. Alexandrou , M. Constantinou , K. Hadjiyiannakou , Ch. Kallidonis , G. Koutsou , K. Jansen , Ch. Wiese , A. Vaquero Avilés-Casco

We present results for the mass spectrum and decay constants using non-perturbatively O(a) improved Wilson fermions. Three values of $\beta$ and 30 different quark masses are used to obtain the chiral and continuum limits. Special emphasis…

High Energy Physics - Lattice · Physics 2015-06-25 M. Goeckeler , R. Horsley , D. Petters , D. Pleiter , P. E. L. Rakow , G. Schierholz , P. Stephenson

The QCDSF/UKQCD collaboration has an ongoing program to calculate nucleon matrix elements with two flavours of dynamical O(a) improved Wilson fermions. Here we present recent results on the electromagnetic form factors, the quark momentum…

High Energy Physics - Lattice · Physics 2008-11-26 M. Göckeler , Ph. Hägler , R. Horsley , Y. Nakamura , D. Pleiter , P. E. L. Rakow , A. Schäfer , G. Schierholz , W. Schroers , H. Stüben , J. M. Zanotti

We present a study of the effects of improvement on light-quark physics using the Fermilab formalism. The calculations were performed at three different lattice spacings, with the SW action and traditional Wilson action (both tadpole…

High Energy Physics - Lattice · Physics 2009-03-09 Brian Gough , Tetsuya Onogi , Jim Simone

We calculate connected and disconnected contributions to the flavour singlet scalar density amplitude of the nucleon in a full QCD lattice simulation with $n_f=2$ dynamical Wilson fermions at $\beta=5.6$ on a $16^3 \times 32$ lattice. We…

High Energy Physics - Lattice · Physics 2012-08-27 SESAM-Collaboration , : , S. Güsken , P. Ueberholz , J. Viehoff , N. Eicker , P. Lacock , T. Lippert , K. Schilling , A. Spitz , Th. Struckmann

For the first time, we compute non-perturbatively, i.e. without lattice perturbation theory, the renormalization constants of two-fermion operators in the quenched approximation at $\beta=6.0$, 6.2 and 6.4 using the Wilson and the…

High Energy Physics - Phenomenology · Physics 2009-10-31 V. Gimenez

We determine the light baryon spectrum on ensembles generated by the Coordinated Lattice Simulations (CLS) effort, employing $N_f=2+1$ flavours of non-perturbatively improved Wilson fermions. The hadron masses are interpolated and…