Results from 2+1 flavours of SLiNC fermions (2009)
Bietenholz, W., Bornyakov, V., Cundy, N., Göckeler, M., Horsley, R., Kennedy, A. D., ...
QCD results are presented for a 2+1 flavour fermion clover action (which we call the SLiNC action). A method of tuning the quark masses to their physical values is discussed. In this method the...
Bornyakov, V. G., Horsley, R., Morozov, S. M., Nakamura, Y., Polikarpov, M. I., Rakow, P. E. L., ...
The critical temperature and the nature of the QCD finite temperature phase transition are determined for Nf=2 dynamical flavors of nonperturbatively improved Wilson fermions. The calculations are...
A Non-Perturbative Operator Product Expansion (2009)
Bietenholz, W., Cundy, N., Goeckeler, M., Horsley, R., Perlt, H., Pleiter, D., ...
Nucleon structure functions can be observed in Deep Inelastic Scattering experiments, but it is an outstanding challenge to confront them with fully non-perturbative QCD results. For this purpose we...
Electroproduction of the N*(1535) resonance at large momentum transfer (2009)
Braun, V. M., Göckeler, M., Horsley, R., Kaltenbrunner, T., Lenz, A., Nakamura, Y., ...
We report on the first lattice calculation of light-cone distribution amplitudes of the N*(1535) resonance, which are used to calculate the transition form factors at large momentum transfers using...
Non-perturbative improvement of stout-smeared three flavour clover fermions (2009)
Cundy, N., Göckeler, M., Horsley, R., Kaltenbrunner, T., Kennedy, A. D., Nakamura, Y., ...
We discuss a 3-flavour lattice QCD action with clover improvement in which the fermion matrix has single level stout smearing for the hopping terms together with unsmeared links for the clover term....
Nucleon distribution amplitudes and proton decay matrix elements on the lattice (2008)
Braun, V. M., Göckeler, M., Horsley, R., Kaltenbrunner, T., Nakamura, Y., Pleiter, D., ...
Baryon distribution amplitudes (DAs) are crucial for the theory of hard exclusive reactions. We present a calculation of the first few moments of the leading-twist nucleon DA within lattice QCD. In...
Clover improvement for stout-smeared 2+1 flavour SLiNC fermions: non-perturbative results (2008)
Cundy, N., Göckeler, M., Horsley, R., Kaltenbrunner, T., Kennedy, A. D., Nakamura, Y., ...
We discuss an action in which the fermion matrix has single level stout smearing for the hopping terms together with unsmeared links for the clover term. With the (tree level) Symanzik improved gluon...
Extracting the rho resonance from lattice QCD simulations at small quark masses (2008)
Göckeler, M., Horsley, R., Nakamura, Y., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
Using established relations between the scattering matrix in infinite volume and the two-particle spectrum in a periodic box, we compute the mass and width of the rho meson from simulations of N_f=2...
Non-perturbative renormalization of three-quark operators (2008)
Göckeler, M., Horsley, R., Kaltenbrunner, T., Nakamura, Y., Pleiter, D., Rakow, P. E. L., ...
High luminosity accelerators have greatly increased the interest in semi-exclusive and exclusive reactions involving nucleons. The relevant theoretical information is contained in the nucleon...
Clover improvement for stout-smeared 2+1 flavour SLiNC fermions: perturbative results (2008)
Horsley, R., Rakow, P. E. L., Perlt, H., Schierholz, G., Schiller, A.
For the Stout Link Non-perturbative Clover (SLiNC) action we determine in one-loop lattice perturbation theory the critical hopping parameter $\kappa_c$ and the clover parameter $c_{SW}$ which is...
Nucleon structure in terms of OPE with non-perturbative Wilson coefficients (2008)
Bietenholz, W., Cundy, N., Gockeler, M., Horsley, R., Perlt, H., Pleiter, D., ...
Lattice calculations could boost our understanding of Deep Inelastic Scattering by evaluating moments of the Nucleon Structure Functions. To this end we study the product of electromagnetic currents...
The electric dipole moment of the nucleon from simulations at imaginary vacuum angle theta (2008)
Horsley, R., Izubuchi, T., Nakamura, Y., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
We compute the electric dipole moment of proton and neutron from lattice QCD simulations with N_f=2 flavors of dynamical quarks at imaginary vacuum angle theta. The calculation proceeds via the CP...
Horsley, R., Perlt, H., Rakow, P. E. L., Schierholz, G., Schiller, A.
Using plaquette and Symanzik improved gauge action and stout link clover fermions we determine the improvement coefficient $c_{SW}$ in one-loop lattice perturbation theory from the off-shell...
The Spin Structure of the Pion. (2008)
D. Brömmel, DESY Forschung Hochenergiephysik, M. Diehl, M. Göckeler, Ph. Hägler, R. Horsley, ...
Journal article
The operator product expansion on the lattice (2007)
Bietenholz, W., Cundy, N., Göckeler, M., Horsley, R., Perlt, H., Pleiter, D., ...
We investigate the Operator Product Expansion (OPE) on the lattice by directly measuring the product (where J is the vector current) and comparing it with the expectation values of bilinear...
Probing the chiral limit with clover fermions II: The baryon sector (2007)
Göckeler, M., Hägler, Philipp, Horsley, R., Nakamura, Y., Ohtani, M., Pleiter, D., ...
Algorithmic progress in recent years made it possible to simulate QCD with Nf=2 flavours of O(a)-improved Wilson fermions at very light quark masses. We present the current results for baryon...
Pion and Rho Structure Functions from Lattice QCD (2007)
C. Best, M. Göckeler, R. Horsley, H. Perlt, P. Rakow, ...
We calculate the lower moments of the deep-inelastic structure functions of the pion and the rho meson on the lattice. Of particular interest to us are the spin-dependent structure functions of the...
Distribution Amplitudes of Vector Mesons (2007)
Braun, V. M., Brömmel, D., Göckeler, M., Horsley, R., Nakamura, Y., Perlt, H., ...
Results are presented for the lowest moment of the distribution amplitude for the K-star vector meson. Both longitudinal and transverse moments are investigated. We use two flavours of O(a) improved...
Moments of nucleon distribution amplitudes from irreducible three-quark operators (2007)
Göckeler, M., Horsley, R., Kaltenbrunner, T., Nakamura, Y., Pleiter, D., Rakow, P. E. L., ...
Semi-exclusive and exclusive processes are becoming more and more important in high energy physics since they are excellently suited to study the internal hadronic structure. To analyze such...
Brommel, QCDSF Collaboration: D., Horsley, R., Morozov, S. M., Nakamura, Y., Pleiter, D., Schierholz, G., ...
We present first results from the QCDSF collaboration for the kaon semileptonic decay form factors at zero momentum transfer, using two flavours of non-perturbatively O(a)-improved Wilson quarks. A...
Nucleon electromagnetic form factors with Wilson fermions (2007)
Gockeler, M., Hagler, Ph., Horsley, R., Nakamura, Y., Ohtani, M., Pleiter, D., ...
The nucleon electromagnetic form factors continue to be of major interest for experimentalists and phenomenologists alike. They provide important insights into the structure of nuclear matter. For a...
Moments of generalized parton distributions and quark angular momentum of the nucleon (2007)
Ohtani, QCDSF/UKQCD Collaboration: M., Brommel, D., Gockeler, M., Hagler, Ph., Horsley, R., Nakamura, Y., ...
The internal structure of hadrons is important for a variety of topics, including the hadron form factors, proton spin and spin asymmetry in polarized proton scattering. For a systematic study...
Perturbative determination of $c_{SW}$ with Symanzik improved gauge action and stout smearing (2007)
Horsley, R., Perlt, H., Rakow, P. E. L., Schierholz, G., Schiller, A.
We determine the improvement factor $c_{SW}$ in one-loop lattice perturbation theory for the plaquette and Symanzik improved gauge actions. The fermionic action is ${\mathcal{O}(a)}$ clover improved...
The spin structure of the pion (2007)
Brömmel, D., Diehl, M., Göckeler, M., Hägler, Ph., Horsley, R., Nakamura, Y., ...
We present the first calculation of the transverse spin structure of the pion in lattice QCD. We find a characteristic asymmetry in the spatial distribution of transversely polarized quarks. This...
The Pion Form Factor from Lattice QCD with two Dynamical Flavours. (2007)
D. Brömmel, DESY Forschung Hochenergiephysik, M. Diehl, M. Göckeler, P. Hägler, R. Horsley, ...
Journal article
D. Brömmel, DESY Forschung Hochenergiephysik, R. Horsley, S.M. Morozov, Y. Nakamura, ...
Contribution to a conf. proceeding (journal)
M. Ohtani, DESY Forschung Hochenergiephysik, D. Brömmel, M. Göckeler, Ph. Hägler, ...
Contribution to a conf. proceeding (journal)
Quark Distributions in the Pion. 2007-07-30 - 2007-08-04 (2007)
D. Brömmel, DESY Forschung Hochenergiephysik, M. Diehl, M. Göckeler, P. Hägler, ...
Contribution to a conf. proceeding (journal)
Probing the chiral limit with clover fermions II: The baryon sector. 2007-07-30 - 2007-08-04 (2007)
M. Göckeler, P. Hägler, R. Horsley, Y. Nakamura, ...
Contribution to a conf. proceeding (book/online)
Distribution Amplitudes of Vector Mesons. 2007-07-30 - 2007-08-04 (2007)
V.M. Braun, DESY Forschung Hochenergiephysik, D. Brömmel, M. Göckeler, R. Horsley, ...
Contribution to a conf. proceeding (journal)
The Spin Structure of the Pion. (2007)
D. Brömmel, DESY Forschung Hochenergiephysik, M. Diehl, M. Göckeler, Ph. Hägler, R. Horsley, ...
Internal report | Preprint
Transverse spin structure of the nucleon from lattice QCD simulations (2006)
Göckeler, M., Hägler, Ph., Horsley, R., Nakamura, Y., Pleiter, D., Rakow, P. E. L., ...
We present the first calculation in lattice QCD of the lowest two moments of transverse spin densities of quarks in the nucleon. They encode correlations between quark spin and orbital angular...
Nucleon Form Factors: Probing the Chiral Limit (2006)
Gockeler, M., Hageler, Ph., Horsley, R., Nakamura, Y., Pleiter, D., Rakow, P. E. L., ...
The electromagnetic form factors provide important hints for the internal structure of the nucleon and continue to be of major interest for experimentalists. For an intermediate range of momentum...
Simulating at Realistic Quark Masses: Light quark masses (2006)
Göckeler, M., Horsley, R., Nakamura, Y., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
We present new results for light quark masses. The calculations are performed using two flavours of $O(a)$ improved Wilson fermions. We have reached lattice spacings as small as $a \sim 0.07$fm and...
Operator product expansion on the lattice: analytic Wilson coefficients (2006)
Göckeler, M., Horsley, R., Perlt, H., Rakow, P. E. L., Schierholz, G., Schiller, A.
We present first results for Wilson coefficients of operators up to first order in the covariant derivatives for the case of Wilson fermions. They are derived from the off-shell Compton scattering...
Simulating at Realistic Quark Masses: Pseudoscalar Decay Constants and Chiral Logarithms (2006)
Göckeler, M., Horsley, R., Nakamura, Y., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
Due to improvements in computer performance and algorithms, the rapidly increasing cost for unquenched Wilson-type fermions with lighter quarks has been ameliorated and new simulations are now...
Distribution Amplitudes of Pseudoscalar Mesons (2006)
Braun, V. M., Gockeler, M., Horsley, R., Perlt, H., Pleiter, D., Rakow, P. E. L., ...
We present results for the first two moments of the distribution amplitudes of pseudoscalar mesons. Using two flavors of non-perturbatively improved clover fermions and non-perturbative...
Göckeler, M., Horsley, R., Perlt, H., Rakow, P. E. L., Schierholz, G., Schiller, A.
We consider the renormalisation of composite quark-antiquark operators with one and two lattice covariant derivatives related to the lowest moments of generalised parton distributions (GPDs) and...
Probing Nucleon Structure on the Lattice (2006)
Göckeler, M., Hägler, Ph., Horsley, R., Nakamura, Y., Pleiter, D., Rakow, P. E. L., ...
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...
The pion form factor from lattice QCD with two dynamical flavours (2006)
Brömmel, D., Diehl, M., Göckeler, M., Hägler, Ph., Horsley, R., Nakamura, Y., ...
We compute the electromagnetic form factor of the pion using non-perturbatively O(a) improved Wilson fermions. The calculations are done for a wide range of pion masses and lattice spacings. We check...
Galletly, D., Gürtler, M., Horsley, R., Perlt, H., Rakow, P. E. L., Schierholz, G., ...
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...
Moments of pseudoscalar meson distribution amplitudes from the lattice (2006)
Braun, V. M., Göckeler, M., Horsley, R., Perlt, H., Pleiter, D., Rakow, P. E. L., ...
Based on lattice simulations with two flavours of dynamical, O(a)-improved Wilson fermions we present results for the first two moments of the distribution amplitudes of pseudoscalar mesons at...
Göckeler, M., Horsley, R., Perlt, H., Rakow, P. E. L., Schäfer, A., Schierholz, G., ...
We consider the renormalisation of lattice QCD operators with one and two covariant derivatives related to the first and second moments of generalised parton distributions and meson distribution...
Khan, A. Ali, Göckeler, M., Hägler, Ph., Hemmert, T. R., Horsley, R., Pleiter, D., ...
We present data for the axial coupling constant g_A of the nucleon obtained in lattice QCD with two degenerate flavours of dynamical non-perturbatively improved Wilson quarks. The renormalisation is...
Determining the strange quark mass for 2-flavour QCD (2006)
Göckeler, M., Horsley, R., Irving, A. C., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
Using the O(a) Symanzik improved action an estimate is given for the strange quark mass for unquenched (n_f=2) QCD. The determination is via the axial Ward identity (AWI) and includes a...
Estimating the Unquenched Strange Quark Mass from the Lattice Axial Ward Identity (2006)
Göckeler, M., Horsley, R., Irving, A. C., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
We present a determination of the strange quark mass for two flavours (nf=2) of light dynamical quarks using the axial Ward identity. The calculations are performed on the lattice using O(a) improved...
The Pion Form Factor from Lattice QCD with two Dynamical Flavours. (2006)
D. Brömmel, DESY Forschung Hochenergiephysik, M. Diehl, M. Göckeler, P. Hägler, R. Horsley, ...
Internal report | Preprint
Determining the strange quark mass for 2-flavour QCD. 2005-09-14 - 2005-09-17 (2006)
M. Göckeler, P. Hägler, R. Horsley, D. Pleiter, ...
Contribution to a conf. proceeding (journal)
M. Göckeler, R. Horsley, Y. Nakamura, D. Pleiter, ...
Contribution to a conf. proceeding (book/online)
Determining the strange quark mass for 2-flavour QCD. 2005-09-14 - 2005-09-17 (2006)
M. Göckeler, P. Hägler, R. Horsley, D. Pleiter, ...
Contribution to a conf. proceeding (journal)
M. Göckeler, R. Horsley, Y. Nakamura, D. Pleiter, ...
Contribution to a conf. proceeding (book/online)
Transverse spin structure of the nucleon from lattice QCD simulations. (2006)
M. Göckeler, P. Hägler, R. Horsley, Y. Nakamura, D. Pleiter, ...
Internal report | Preprint
D. Galletly, M. Gürtler, R. Horsley, H. Perlt, ...
Internal report | Preprint
Hadron Phenomenology from Quenched Overlap Fermions. 2005-09-14 - 2005-09-17 (2006)
D. Galletly, M. Gürtler, R. Horsley, K. Koller, ...
Contribution to a conf. proceeding (journal)
A. Ali Khan, M. Göckeler, P. Hägler, T.R. Hemmert, ...
Contribution to a conf. proceeding (journal)
M. Göckeler, R. Horsley, H. Perlt, A. Schäfer, ...
Journal article
Simulating at realistic quark masses: light quark masses. 2006-07-23 - 2006-07-28 (2006)
M. Göckeler, R. Horsley, Y. Nakamura, D. Pleiter, ...
Contribution to a conf. proceeding (book/online)
The pion form factor from lattice QCD with two dynamical flavours. (2006)
D. Brömmel, M. Diehl, M. Göckeler, P. Hägler, R. Horsley, ...
Internal report | Preprint
Nucleon structure from generalized parton distributions in lattice QCD (2005)
Gockeler, M., Hagler, Ph., Horsley, R., Pleiter, D., Rakow, P. E. L., Schafer, A., ...
This talk presents results from the QCDSF-UKQCD collaboration for moments of leading twist generalized parton distributions in two-flavor lattice QCD based on O(a) improved Wilson Fermions. We study...
Gockeler, M., Horsley, R., Perlt, H., Rakow, P. E. L., Schaefer, A., Schierholz, G., ...
We present the non-forward quark matrix elements of operators with one and two covariant derivatives needed for the renormalisation of the first and second moments of generalised parton distributions...
Soffer Bound and Transverse Spin Densities from Lattice QCD (2005)
Diehl, M., Gockeler, M., Hagler, Ph., Horsley, R., Pleiter, D., Rakow, P. E. L., ...
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...
Second moment of the pion's distribution amplitude (2005)
Göckeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schäfer, A., Schierholz, G., ...
We present preliminary results from the QCDSF/UKQCD collaborations for the second moment of the pion's distribution amplitude with two flavours of dynamical fermions. We use nonperturbatively...
The axial charge of the nucleon on the lattice and in chiral perturbation theory (2005)
Khan, A. Ali, Göckeler, M., Hägler, P., Hemmert, T. R., Horsley, R., Irving, A. C., ...
We present recent Monte Carlo data for the axial charge of the nucleon obtained by the QCDSF-UKQCD collaboration for N_f=2 dynamical quarks. We compare them with formulae from chiral perturbation...
Nucleon Structure from Quenched Overlap Fermions (2005)
Galletly, D., Gürtler, M., Horsley, R., Koller, K., Linke, V., Rakow, P. E. L., ...
We compute the lowest moments of the nucleon's structure functions using quenched overlap fermions at two different lattice spacings. The renormalisation is done nonperturbatively in the...
Non-perturbative renormalisation for overlap fermions (2005)
Gürtler, M., Horsley, R., Rakow, P. E. L., Roberts, C. J., Schierholz, G., Streuer, T.
Using non-perturbative techniques we have found the renormalisation factor, Z, in the RI-MOM scheme for quark bilinear operators in quenched QCD. We worked with overlap fermions using the...
Meson decay constants from Nf=2 clover fermions (2005)
Göckeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schierholz, G., Schroers, W., ...
We present recent results for meson decay constants calculated on configurations with two flavours of O(a)-improved Wilson fermions. Non-perturbative renormalisation is applied and quark mass...
A determination of the strange quark mass for unquenched clover fermions using the AWI (2005)
Göckeler, M., Horsley, R., Irving, A. C., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
Using the O(a) Symanzik improved action an estimate is given for the strange quark mass for unquenched (nf=2) QCD. The determination is via the axial Ward identity (AWI) and includes a...
Structure of the Pion from Full Lattice QCD (2005)
Brömmel, D., Diehl, M., Göckeler, M., Hägler, Ph., Horsley, R., Pleiter, D., ...
Moments of generalised parton distributions can be related to off-forward matrix elements of local operators. We calculate a few of the leading twist matrix elements for the pion on the lattice. The...
Horsley, R., Perlt, H., Rakow, P. E. L., Schierholz, G., Schiller, A.
We calculate lattice renormalisation constants of local and one-link quark operators for overlap fermions and improved gauge actions in one-loop perturbation theory. For the local operators we stout...
Quark helicity flip generalized parton distributions from two-flavor lattice QCD (2005)
Gockeler, M., Hagler, Ph., Horsley, R., Pleiter, D., Rakow, P. E. L., Schafer, A., ...
We present an initiatory study of quark helicity flip generalized parton distributions (GPDs) in n_f=2 lattice QCD, based on clover-improved Wilson fermions for a large number of coupling constants...
Göckeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schäfer, A., Schierholz, G., ...
The reduced matrix elements a_2 and d_2 are computed in lattice QCD with N_f=2 flavors of light dynamical (sea) quarks. For proton and neutron targets we obtain as our best estimates d_2^(p)=0.004(5)...
Horsley, R., Perlt, H., Rakow, P. E. L., Schierholz, G., Schiller, A.
We compute lattice renormalisation constants of one-link quark operators ({\it i.e.} operators with one covariant derivative) for overlap fermions and L\"uscher-Weisz gauge action in one-loop...
A Determination of the Lambda Parameter from Full Lattice QCD (2005)
Göckeler, M., Horsley, R., Irving, A. C., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
We present a determination of the QCD parameter Lambda in the quenched approximation (n_f=0) and for two flavours (n_f=2) of light dynamical quarks. The calculations are performed on the lattice...
Generalized parton distributions and transversity from full lattice QCD (2005)
Gockeler, M., Hagler, Ph., Horsley, R., Pleiter, D., Rakow, P. E. L., Schafer, A., ...
We present here the latest results from the QCDSF collaboration for moments of generalized parton distributions and transversity in two-flavour QCD, including a preliminary analysis of the pion mass...
Goeckeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schaefer, A., Schierholz, G., ...
The reduced matrix elements a_2 and d_2 are computed in lattice QCD with N_f=2 flavors of light dynamical (sea) quarks. For proton and neutron targets we obtain as our best estimates d_2^(p)=0.004(5)...
The Lattice Calculation of Moments of Structure Functions (2004)
Some aspects of recent QCDSF-UKQCD nucleon moments of structure function computations (both quenched and unquenched) are reviewed in an effort to explore the light quark mass regime, lattice spacing...
Generalized Parton Distributions in Full Lattice QCD (2004)
Göckeler, M., Hägler, Ph., Horsley, R., Pleiter, D., Rakow, P. E. L., Schäfer, A., ...
We present recent results on generalized parton distributions from dynamical lattice QCD calculations. Our set of twelve different combinations of couplings and quark masses allows for a preliminary...
Göckeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schierholz, G.
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...
Perturbative Renormalisation of the Second Moment of Generalised Parton Distributions (2004)
Göckeler, M., Horsley, R., Perlt, H., Rakow, P. E. L., Schäfer, A., Schierholz, G., ...
We calculate the non-forward quark matrix elements of operators with two covariant derivatives needed for the renormalisation of the second moment of generalised parton distributions in one-loop...
A lattice determination of g_A and from overlap fermions (2004)
Gürtler, M., Horsley, R., Linke, V., Perlt, H., Rakow, P. E. L., Schierholz, G., ...
We present results for the nucleon's axial charge g_A and the first moment of the unpolarized parton distribution function from a simulation of quenched overlap fermions.
Determination of Lambda in quenched and full QCD - an update (2004)
Göckeler, M., Horsley, R., Irving, A. C., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
We present an update on our previous determination of the Lambda parameter in QCD. The main emphasis is on results for two flavours of light dynamical quarks, where we can now almost double the...
Axial and tensor charge of the nucleon with dynamical fermions (2004)
Khan, A. Ali, Göckeler, M., Hägler, P., Hemmert, T. R., Horsley, R., Irving, A. C., ...
We present preliminary results for the axial and tensor charge of the nucleon obtained from simulations with N_f=2 clover fermions. A comparison with chiral perturbation theory is attempted.
Generalized parton distributions and structure functions from full lattice QCD (2004)
Göckeler, M., Hägler, P., Horsley, R., Pleiter, D., Rakow, P. E. L., Schäfer, A., ...
We present here the latest results from the QCDSF collaboration for (moments of) structure functions and generalized form factors in full QCD with Nf=2 O(a)-improved Wilson fermions based on...
Determination of Light and Strange Quark Masses from Full Lattice QCD (2004)
Göckeler, M., Horsley, R., Irving, A. C., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
We compute the light and strange quark masses m_l = (m_u+m_d)/2 and m_s, respectively, in full lattice QCD with N_f=2 flavors of light dynamical quarks. The renormalization constants, which convert...
One-loop renormalisation for the second moment of GPDs with Wilson fermions (2004)
Göckeler, M., Horsley, R., Perlt, H., Rakow, P. E. L., Schäfer, A., Schierholz, G., ...
We calculate the non-forward quark matrix elements for operators with two covariant derivatives in one-loop lattice perturbation theory using Wilson fermions. These matrix elements are needed in the...
One-loop renormalisation of quark bilinears for overlap fermions with improved gauge actions (2004)
Horsley, R., Perlt, H., Rakow, P. E. L., Schierholz, G., Schiller, A.
We compute lattice renormalisation constants of local bilinear quark operators for overlap fermions and improved gauge actions. Among the actions we consider are the Symanzik, L\"uscher-Weisz,...
The nucleon mass in N_f=2 lattice QCD: finite size effects from chiral perturbation theory (2003)
Khan, A. Ali, Bakeyev, T., Göckeler, M., Hemmert, T. R., Horsley, R., Irving, A. C., ...
In the framework of relativistic SU(2)_f baryon chiral perturbation theory we calculate the volume dependence of the nucleon mass up to and including O(p^4). Since the parameters in the resulting...
Vacuum Polarisation and Hadronic Contribution to muon g-2 from Lattice QCD (2003)
Göckeler, M., Horsley, R., Kürzinger, W., Pleiter, D., Rakow, P. E. L., Schierholz, G.
We compute the vacuum polarisation on the lattice in quenched QCD using non-perturbatively improved Wilson fermions. Above Q^2 of about 2 GeV^2 the results are very close to the predictions of...
Khan, A. Ali, Bakeyev, T., Göckeler, M., Hemmert, T. R., Horsley, R., Irving, A. C., ...
The finite size effects on nucleon masses are calculated in relativistic chiral perturbation theory. Results are compared with two-flavor lattice results.
Structure of the Nucleon (2003)
Göckeler, M., Hemmert, T. R., Horsley, R., Pleiter, D., Rakow, P. E. L., Schäfer, A., ...
Generalized parton distributions provide information on the longitudinal and transverse distribution of partons in the fast moving nucleon. Furthermore, they contain information on the spin structure...
Structure functions and form factors close to the chiral limit from lattice QCD (2003)
Bakeyev, T., Galletly, D., Göckeler, M., Gürtler, M., Horsley, R., Joó, B., ...
Results for nucleon matrix elements (arising from moments of structure functions) and form factors from a mixture of runs using Wilson, clover and overlap fermions (both quenched and unquenched) are...
Vacuum polarisation and the muon g-2 in lattice QCD (2003)
Göckeler, M., Horsley, R., Kürzinger, W., Pleiter, D., Rakow, P. E. L., Schierholz, G.
We measure the hadronic contribution to the vacuum polarisation tensor, and use it to estimate the hadronic contribution to (g-2)_mu, the muon anomalous magnetic moment.
Galletly, D., Gürtler, M., Horsley, R., Joo, B., Kennedy, A. D., Perlt, H., ...
We present first results from a simulation of quenched overlap fermions with improved gauge field action. Among the quantities we study are the spectral properties of the overlap operator, the chiral...
Chiral Perturbation Theory and Finite Size Effects on the Nucleon Mass in unquenched QCD (2003)
Khan, A. Ali, Bakeyev, T., Göckeler, M., Hemmert, T. R., Horsley, R., Irving, A. C., ...
We calculate finite size effects on nucleon masses in chiral perturbation theory. We confront the theoretical predictions with N_f=2 lattice results and discuss chiral extrapolation formulae.
Accelerating Hasenbusch's acceleration of Hybrid Monte Carlo (2003)
Khan, A. Ali, Bakeyev, T., Göckeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., ...
Hasenbusch has proposed splitting the pseudo-fermionic action into two parts, in order to speed-up Hybrid Monte Carlo simulations of QCD. We have tested a different splitting, also using...
Bakeyev, T., Gockeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
By considering the local vector current between nucleon states and imposing charge conservation, we determine its renormalisation constant and quark mass improvement coefficient for Symanzik $O(a)$...
Generalized Parton Distributions from Lattice QCD (2003)
Göckeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schäfer, A., Schierholz, G., ...
We perform a quenched lattice calculation of the first moment of twist-two generalized parton distribution functions of the proton, and assess the total quark (spin and orbital angular momentum)...
Accelerating the Hybrid Monte Carlo algorithm (2003)
Khan, A. Ali, Bakeyev, T., Göckeler, M., Horsley, R., Pleiter, D., Rakow, P., ...
An algorithm for separating the high- and low-frequency molecular dynamics modes in Hybrid Monte Carlo simulations of gauge theories with dynamical fermions is presented. The separation is based on...
Nucleon electromagnetic form factors on the lattice and in chiral effective field theory (2003)
Göckeler, M., Hemmert, T. R., Horsley, R., Pleiter, D., Rakow, P. E. L., Schäfer, A., ...
We compute the electromagnetic form factors of the nucleon in quenched lattice QCD, using non-perturbatively improved Wilson fermions, and compare the results with phenomenology and chiral effective...
Low-Lying Fermion Modes: Dynamical versus Quenched (2002)
Horsley, R., Kovacs, T. G., Linke, V., Pleiter, D., Schierholz, G., Streuer, Th.
We compare the low-lying eigenmodes of the O(a) improved Wilson-Dirac operator on quenched and dynamical configurations and investigate methods of probing the topological properties of gauge...
Calculation of Moments of Structure Functions (2002)
Göckeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schäfer, A., Schierholz, G.
The progress on the lattice computation of low moments of both the unpolarised and polarised nucleon structure functions is reviewed with particular emphasis on continuum and chiral extrapolations...
Structure functions near the chiral limit (2002)
Goeckeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schierholz, G.
We compute hadron masses and the lowest moments of unpolarized and polarized nucleon structure functions down to pion masses of 300 MeV, in an effort to make unambiguous predictions at the physical...
Bakeyev, T., Gockeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schafer, A., ...
By considering the local vector current between nucleon states and imposing charge conservation we determine, for $O(a)$ improved Wilson fermions, its renormalisation constant and quark mass...
Finite Size Effects in Nucleon Masses in Dynamical QCD (2002)
Khan, A. Ali, Bakeyev, T., Göckeler, M., Horsley, R., Irving, A. C., Pleiter, D., ...
For lattice calculations with light dynamical quarks, finite size effects have become an important aspect. We study finite size effects in nucleon masses on N_f=2 dynamical lattices of 1-2 fm....
A lattice study of the spin structure of the Lambda hyperon (2002)
Göckeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schaefer, S., Schäfer, A., ...
The internal spin structure of the Lambda is of special importance for the understanding of the spin structure of hadrons in general. The comparison between the nucleon and Lambda allows for a test...
Applied lattice gauge calculations: diquark content of the nucleon (2002)
Göckeler, M., Horsley, R., Klaus, B., Pleiter, D., Rakow, P. E. L., Schaefer, S., ...
As an example of an application of lattice QCD we describe a computation of four-quark operators in the nucleon. The results are interpreted in a diquark language.
Lattice Calculation of Baryon Masses using the Clover Fermion Action (2002)
Gockeler, QCDSF Collaboration: M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
We present a calculation of the lowest-lying baryon masses in the quenched approximation to QCD. The calculations are performed using a non-perturbatively improved clover fermion action, and a...
Excited nucleon spectrum using a non-perturbatively improved clover fermion action (2001)
Gockeler, QCDSF Collaboration: M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
We discuss the extraction of negative-parity baryon masses from lattice QCD calculations. The mass of the lowest-lying negative-parity $J = 1/2^{-}$ state is computed in quenched lattice QCD using an...
Low-lying fermion modes of Nf=2 improved Wilson fermions (2001)
Horsley, R., Kovacs, T. G., Linke, V., Pleiter, D., Schierholz, G.
We present preliminary results for the topological charge and susceptibility determined from the low-lying eigenmodes of the Wilson-Dirac operator. These modes have been computed on dynamical...
Progress towards a lattice determination of (moments of) nucleon structure functions (2001)
Capitani, S., Gockeler, M., Horsley, R., Pleiter, D., Rakow, P., Stuben, H., ...
Using unimproved and non-perturbatively O(a) improved Wilson fermions, results are given for the three lowest moments of unpolarised nucleon structure functions. Renormalisation, chiral extrapolation...
The strong coupling constant from lattice QCD with N_f=2 dynamical quarks (2001)
Booth, S., Göckeler, M., Horsley, R., Irving, A. C., Joo, B., Pickles, S., ...
We compute $\Lambda_{\bar{MS}}$ for two flavors of light dynamical quarks using non-perturbatively $O(a)$ improved Wilson fermions. We improve on a recent calculation by employing Pad\'e-improved...
Separating perturbative and non-perturbative contributions to the plaquette (2001)
Horsley, R., Rakow, P. E. L., Schierholz, G.
We try to separate the perturbative and non-perturbative contributions to the plaquette of pure SU(3) gauge theory. To do this we look at the large-n asymptotic behaviour of the perturbation series...
The spin structure of the Lambda hyperon in quenched lattice QCD (2001)
Göckeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schaefer, S., Schäfer, A., ...
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...
Nucleon form factors and structure functions from Lattice QCD (2001)
Göckeler, M., Horsley, R., Pleiter, D., Rakow, P. E. L., Schierholz, G.
In this talk we highlight recent lattice calculations of the nucleon form factors and structure functions.
Negative-parity Baryon Masses using an O(a)-improved Fermion Action (2001)
Collaboration, LHPC, Collaboration, QCDSF, Gockeler, UKQCD Collaboration: M., Horsley, R., Maynard, C. M., Pleiter, D., ...
We present a calculation of the mass of the lowest-lying negative-parity J=1/2- state in quenched QCD. Results are obtained using a non-perturbatively O(a)-improved clover fermion action, and a...
A lattice evaluation of four-quark operators in the nucleon (2001)
Göckeler, M., Horsley, R., Klaus, B., Pleiter, D., Rakow, P. E. L., Schaefer, S., ...
Nucleon matrix elements of various four-quark operators are evaluated in quenched lattice QCD using Wilson fermions. Some of these operators give rise to twist-four contributions to nucleon structure...
Determination of $\Lambda_{\overline{MS}}$ from quenched and $N_f = 2$ dynamical QCD (2001)
Booth, S., Göckeler, M., Horsley, R., Irving, A. C., Joo, B., Pickles, S., ...
The scale parameter $\Lambda_{\overline{MS}}$ is computed on the lattice in the quenched approximation and for $N_f = 2$ flavors of light dynamical quarks. The dynamical calculation is done with...
The Vacuum Polarization: Power Corrections beyond OPE ? (2000)
Gockeler, M., Horsley, R., Kurzinger, W., Linke, V., Pleiter, D., Rakow, P. E. L., ...
We compute the vacuum polarization on the lattice using non-perturbatively O(a) improved Wilson fermions. The result is compared with the operator product expansion (OPE).
A lattice calculation of the nucleon's spin-dependent structure function g_2 revisited (2000)
Gockeler, M., Horsley, R., Kurzinger, W., Oelrich, H., Pleiter, D., Rakow, P. E. L., ...
Our previous calculation of the spin-dependent structure function g_2 is revisited. The interest in this structure function is to a great extent motivated by the fact that it receives contributions...
Determining gA using non-perturbatively O(a) improved Wilson fermions (2000)
A completely non-perturbative estimate is given for gA using both quenched and unquenched O(a) improved Wilson fermions. Particular attention is paid to the determination of the axial renormalisation...
Four-quark operators in hadrons (2000)
Capitani, S., Gockeler, M., Horsley, R., Klaus, B., Kurzinger, W., Petters, D., ...
We present calculations of matrix elements of 4-quark operators in the pion and in the nucleon extracted from quenched Monte Carlo simulations at beta = 6.0 using Wilson fermions. These operators are...
Renormalisation and off-shell improvement in lattice perturbation theory (2000)
Capitani, S., Goeckeler, M., Horsley, R., Perlt, H., Rakow, P. E. L., Schierholz, G., ...
We discuss the improvement of flavour non-singlet point and one-link lattice quark operators, which describe the quark currents and the first moment of the DIS structure functions respectively....
Quenched QCD near the chiral limit (2000)
Gockeler, M., Horsley, R., Petters, D., Pleiter, D., Rakow, P. E. L., Schierholz, G.
A numerical study of quenched QCD for light quarks is presented using O(a) improved fermions. Particular attention is paid to the possible existence and determination of quenched chiral logarithms. A...
On-shell and off-shell improvement for Ginsparg-Wilson fermions (1999)
Capitani, S., Goeckeler, M., Horsley, R., Rakow, P. E. L., Schierholz, G.
We discuss the improvement of bilinear fermionic operators for Ginsparg-Wilson fermions. We present explicit formulae for improved Green's functions, which apply both on-shell and off-shell.
Hadron masses and decay constants in quenched QCD (1999)
Goeckeler, M., Horsley, R., Petters, D., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
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...
The Polarized Structure Function g_2: A Lattice Study Revisited (1999)
Göckeler, M., Horsley, R., Kürzinger, W., Oelrich, H., Rakow, P., Schierholz, G.
A recent lattice calculation of the spin-dependent structure function g_2 is revisited. It has been recognized that the twist-three operator, which gives rise to d_2, mixes non-perturbatively with...
Higher-twist contributions to the Structure Functions coming from 4-fermion operators (1999)
Capitani, S., Göckeler, M., Horsley, R., Klaus, B., Linke, V., Rakow, P., ...
We evaluate the contribution of a class of higher-twist operators to the lowest moment of the Structure Functions, by computing appropriate matrix elements of six four-fermion operators in the...
Operator improvement for Ginsparg-Wilson fermions (1999)
Capitani, S., Goeckeler, M., Horsley, R., Rakow, P. E. L., Schierholz, G.
The improvement of fermionic operators for Ginsparg-Wilson fermions is investigated. We present explicit formulae for improved Green's functions, which apply both on-shell and off-shell.
Light quark masses from the lattice (1999)
Gockeler, M., Horsley, R., Klaus, B., Kurzinger, W., Oelrich, H., Petters, D., ...
A completely non-perturbative estimate is given for the u/d and strange quark masses in quenched QCD using O(a) improved fermions and, for comparison, Wilson fermions. For improved fermions we find...
Higher-Twist Contribution to Pion Structure Function: 4-Fermi Operators (1999)
Capitani, S., Göckeler, M., Horsley, R., Klaus, B., Linke, V., Rakow, P. E. L., ...
We present quenched lattice QCD results for the contribution of higher-twist operators to the lowest non-trivial moment of the pion structure function. To be specific, we consider the combination...
A Lattice Determination of Light Quark Masses (1999)
Gockeler, M., Horsley, R., Oelrich, H., Petters, D., Pleiter, D., Rakow, P. E. L., ...
A fully non-perturbative lattice determination of the up/down and strange quark masses is given for quenched QCD using both, $O(a)$ improved Wilson fermions and ordinary Wilson fermions. For the...
Higher-twist corrections to nucleon structure functions from lattice QCD (1999)
Capitani, S., Göckeler, M., Horsley, R., Petters, D., Pleiter, D., Rakow, P., ...
A genuinely non-perturbative evaluation of higher-twist contributions to the structure functions of the nucleon, with all mixing effects and renormalon ambiguities taken care of, is presented....
Towards a lattice calculation of $\Delta q$ and $\delta q$ (1999)
Capitani, S., Gockeler, M., Horsley, R., Perlt, H., Petters, D., Pleiter, D., ...
Within the framework of lattice QCD a high statistics computation of the nucleon axial and tensor charges is given. Particular attention is paid to the chiral and continuum extrapolations.
Mass spectrum and decay constants in the continuum limit (1998)
Goeckeler, M., Horsley, R., Linke, V., Pleiter, D., Rakow, P. E. L., Schierholz, G., ...
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.
Renormalization of four-fermion operators for higher twist calculations (1998)
Capitani, S., Göckeler, M., Horsley, R., Perlt, H., Rakow, P. E. L., Schierholz, G., ...
The evaluation of the higher twist contributions to Deep Inelastic Scattering amplitudes involves a non trivial choice of operator bases for the higher orders of the OPE expansion of the two hadronic...
Towards a Non-Perturbative Calculation of DIS Wilson Coefficients (1998)
Capitani, S., Göckeler, M., Horsley, R., Oelrich, H., Petters, D., Rakow, P., ...
We verify the operator product expansion (OPE) of deep inelastic scattering (DIS) on the lattice and present first results of a non-perturbative calculation of the Wilson coefficients.
Nucleon form factors and O(a) Improvement (1998)
Capitani, S., Gockeler, M., Horsley, R., Klaus, B., Oelrich, H., Perlt, H., ...
Nucleon form factors have been extensively studied both experimentally and theoretically for many years. We report here on new results of a high statistics quenched lattice QCD calculation of vector...
Resolving Exceptional Configurations in Quenched Lattice QCD (1998)
Göckeler, M., Hoferichter, A., Horsley, R., Pleiter, D., Rakow, P., Schierholz, G., ...
Quenched lattice QCD calculations with Wilson-type fermions at small quark masses are impeded by exceptional configurations. We show how this problem can be resolved in a practicable way without...
Composite operators in lattice QCD: nonperturbative renormalization (1998)
Gockeler, M., Horsley, R., Oelrich, H., Perlt, H., Petters, D., Rakow, P. E. L., ...
We investigate the nonperturbative renormalization of composite operators in lattice QCD restricting ourselves to operators that are bilinear in the quark fields. These include operators which are...
Nonperturbative Renormalisation of Composite Operators in Lattice QCD (1998)
Gockeler, M., Horsley, R., Oelrich, H., Perlt, H., Petters, D., Rakow, P. E. L., ...
We investigate the nonperturbative renormalisation of composite operators in lattice QCD restricting ourselves to operators that are bilinear in the quark fields. These include operators which are...
$O(a)$ Improvement for Quenched Wilson Fermions (1998)
Capitani, S., Goeckeler, M., Horsley, R., Klaus, B., Oelrich, H., Perlt, H., ...
We briefly describe some of our recent results for the mass spectrum and matrix elements using $O(a)$ improved fermions for quenched QCD. Where possible a comparison is made between improved and...
Resolution of the Landau pole problem in QED (1998)
Göckeler, M., Horsley, R., Linke, V., Rakow, P., Schierholz, G., Stüben, H.
We present new numerical results for the renormalized mass and coupling in non-compact lattice QED with staggered fermions. Implications for the continuum limit and the role of the Landau pole are...
Notes for Lectures Presented at the Summer School on Lattice QCD for Beginners (1998)
From The Lattice, R. Horsley, H. Perlt, P. Rakow, G. Schierholz, ...
Is there a Landau Pole Problem in QED? (1997)
Göckeler, M., Horsley, R., Linke, V., Rakow, P., Schierholz, G., Stüben, H.
We investigate a lattice version of QED by numerical simulations. For the renormalized charge and mass we find results which are consistent with the renormalized charge vanishing in the continuum...
Capitani, S., Göckeler, M., Horsley, R., Perlt, H., Rakow, P., Schierholz, G., ...
Some basic concepts are discussed to derive renormalisation factors of local lattice operators relevant to deep inelastic structure functions and to other measurable quantities. These $Z$ factors can...
Spin Structure Functions from Lattice QCD (1997)
Göckeler, M., Horsley, R., Perlt, H., Rakow, P., Schierholz, G., Schiller, A., ...
We report on new results of the spin dependent structure functions $g_1$ and $h_1$ of the nucleon. An attempt is made to convert the moments, which is what one computes on the lattice, to quark...
Lattice Renormalization of Quark Operators (1997)
Goeckeler, M., Horsley, R., Oelrich, H., Perlt, H., Rakow, P. E. L., Schierholz, G., ...
We have technically improved the non-perturbative renormalization method, proposed by Martinelli et al., by using quark momentum sources and sinks. Composite two-fermion operators up to three...
The Deep-Inelastic Structure Functions of $\pi$ and $\rho$ Mesons (1997)
Best, C., Göckeler, M., Horsley, R., Perlt, H., Rakow, P., Schäfer, A., ...
We compute the lower moments of the structure functions of $\pi$ and $\rho$. Of particular interest are the spin-dependent structure functions of the $\rho$ as they give new information about quark...
Non-perturbative improvement and renormalization of lattice operators (1997)
Capitani, S., Goeckeler, M., Horsley, R., Oelrich, H., Perlt, H., Pleiter, D., ...
The Alpha Collaboration has proposed an optimal value for c_SW in the Sheikholeslami-Wohlert action, chosen to remove O(a) effects. To measure hadronic matrix elements to the same accuracy we need a...
New results for non-perturbative order(a) improvement in light hadrons (1997)
Goeckeler, M., Horsley, R., Perlt, H., Rakow, P., Schierholz, G., Schiller, A., ...
We have results from light hadron simulations in quenched QCD at beta=6.0 and 6.2 using non-perturbatively improved Sheikholeslami-Wohlert fermions in an effort to remove all order(a) effects. From...
Perturbative Renormalization of Improved Lattice Operators (1997)
Capitani, S., Goeckeler, M., Horsley, R., Perlt, H., Rakow, P., Schierholz, G., ...
We derive bases of improved operators for all bilinear quark currents up to spin two (including the operators measuring the first moment of DIS Structure Functions), and compute their one-loop...
$O(a)$ Improvement of Nucleon Matrix Elements (1997)
Capitani, S., Goeckeler, M., Horsley, R., Oelrich, H., Perlt, H., Pleiter, D., ...
We report on preliminary results of a high statistics quenched lattice QCD calculation of nucleon matrix elements within the Symanzik improvement programme. Using the recently determined...
Improved Quenched QCD on Large Lattices - First Results (1997)
Goeckeler, M., Horsley, R., Linke, V., Perlt, H., Pleiter, D., Rakow, P., ...
Continuing our investigations of quenched QCD with improved fermions we have started simulations for lattice size 32^3 x 64 at beta=6.2. We present first results for light hadron masses at...
A lattice determination of the second moment of the polarised valence quark distribution (1997)
Goeckeler, M., Horsley, R., Mankiewicz, L., Perlt, H., Rakow, P., Schierholz, G., ...
We perform a Monte Carlo calculation of the second moment of the polarised valence quark distributions in the nucleon, using quenched Wilson fermions. The special feature of this moment is that it is...
Göckeler, M., Horsley, R., Perlt, H., Rakow, P., Schierholz, G., Schiller, A., ...
We compute the hadron mass spectrum, the quark masses and the meson decay constants in quenched lattice QCD with non-perturbatively $O(a)$ improved Wilson fermions. The calculations are done for two...
Hadron Structure Functions from Lattice QCD -- 1997 (1997)
Best, C., Göckeler, M., Horsley, R., Mankiewicz, L., Perlt, H., Rakow, P., ...
We review the status of lattice calculations of the deep-inelastic structure functions of the nucleon. In addition, we present some results on the pion and rho structure functions.
Pion and Rho Structure Functions from Lattice QCD (1997)
Best, C., Göckeler, M., Horsley, R., Perlt, H., Rakow, P., ...
We calculate the lower moments of the deep-inelastic structure functions of the pion and the rho meson on the lattice. Of particular interest to us are the spin-dependent structure functions of the...
The Drell-Yan process and Deep Inelastic Scattering from the lattice (1996)
Goeckeler, M., Horsley, R., Oelrich, H., Perlt, H., Rakow, P. E. L., ...
We report on measurements of the h_1 structure function, relevant to calculating cross-sections for the Drell-Yan process. This is a quantity which can not be measured in Deep Inelastic Scattering,...
The Light Hadron Mass Spectrum with Non-Perturbatively O(a) Improved Wilson Fermions (1996)
Göckeler, M., Horsley, R., Perlt, H., Rakow, P., Schierholz, G., Schiller, A., ...
We compute the light hadron mass spectrum in quenched lattice QCD at $\beta = 6.0$ using the Sheikholeslami-Wohlert fermionic action. The calculation is done for several choices of the coefficient...
First results with non-perturbative fermion improvement (1996)
Göckeler, M., Horsley, R., Ilgenfritz, M., Oelrich, H., Perlt, H., Rakow, P., ...
We present initial results for light hadron masses and nucleon structure functions using a recent proposal for eliminating all $O(a)$ effects from Wilson fermion simulations in the quenched...
Lattice computation of structure functions (1996)
Goeckeler, M., Horsley, R., Perlt, H., Rakow, P., Schierholz, G., ...
Recent lattice calculations of hadron structure functions are described.
Perturbative renormalization of bilinear quark and gluon operators (1996)
Goeckeler, M., Horsley, R., Oelrich, H., Perlt, H., Rakow, P., ...
The renormalisation constants for local bilinear quark operators are calculated using the Sheikholeslami-Wohlert improved action. In addition we compute the renormalisation constant of the leading...
A Preliminary Lattice Study of the Glue in the Nucleon (1996)
Goeckeler, M., Horsley, R., Oelrich, H., Perlt, H., Rakow, P. E. L., ...
About half the mass of a hadron is given from gluonic contributions. In this talk we calculate the chromo-electric and chromo-magnetic components of the nucleon mass. These computations are...
Seeking the Equation of State of Non-Compact Lattice QED (1996)
Göckeler, M., Horsley, R., Linke, V., Rakow, P., Schierholz, G., Stüben, H.
We perform a high statistics calculation of the equation of state for non-compact QED on large lattices. The calculation extends to fermionic correlation lengths of $\approx 8$, and it is combined...
Perturbative Renormalization of Lattice Bilinear Quark Operators (1996)
Göckeler, M., Horsley, R., Perlt, H., Rakow, P., Schierholz, G., ...
Our aim is to compute the lower moments of the unpolarized and polarized deep-inelastic structure functions of the nucleon on the lattice. The theoretical basis of the calculation is the operator...
Goeckeler, M., Horsley, R., Perlt, H., Rakow, P., Schierholz, G., ...
For lattice operators that are relevant to the calculation of moments of nucleon structure functions we investigate the transformation properties under the hypercubic group. We give explicit bases of...
The Status of Lattice Calculations of the Nucleon Structure Functions (1996)
Goeckeler, M., Horsley, R., Oelrich, H., Perlt, H., Rakow, P., ...
We review our progress on the lattice calculation of low moments of both the unpolarised and polarised nucleon structure functions.
Meinulf Gockeler, Roger Horsley, Volkard Linke, Paul Rakow, Gerrit Schierholz, Hinnerk Stuben, ...
a;b
Recent results on the nucleon structure functions from Lattice QCD (1995)
Göckeler, M, Horsley, R, Ilgenfritz, E M, Oelrich, H, Rakow, P, Perlt, H, ...
Polarized Nucleon Structure Functions from Lattice QCD (1995)
Goeckeler, M., Horsley, R., Perlt, H., Rakow, P., Schierholz, G., ...
We describe a high statistics quenched QCD calculation of the moments of the polarized deep-inelastic structure functions g_1 and g_2 of the proton and neutron.
Recent Results on the Nucleon Structure Functions from Lattice QCD (1995)
Göckeler, M., Horsley, R., Oelrich, H., Perlt, H., Rakow, P., ...
We report on recent results of a high statistics lattice calculation of the unpolarized and polarized structure functions of the nucleon.
Non-Perturbative versus Perturbative Renormalization of Lattice Operators (1995)
Göckeler, M., Horsley, R., Oelrich, H., Perlt, H., Rakow, P., ...
Our objective is to compute the moments of the deep-inelastic structure functions of the nucleon on the lattice. A major source of uncertainty is the renormalization of the lattice operators that...
A Lattice Evaluation of the Deep-Inelastic Structure Functions of the Nucleon (1995)
Göckeler, M., Horsley, R., Oelrich, H., Perlt, H., Rakow, P., ...
The lower moments of the unpolarized and polarized deep-inelastic structure functions of the nucleon are calculated on the lattice. The calculation is done with Wilson fermions and for three values...
Polarized and Unpolarized Nucleon Structure Functions from Lattice QCD (1995)
Göckeler, M., Horsley, R., Perlt, H., Rakow, P., Schierholz, G., ...
We report on a high statistics quenched lattice QCD calculation of the deep-inelastic structure functions $F_1$, $F_2$, $g_1$ and $g_2$ of the proton and neutron. The theoretical basis for the...
Hadronic Coupling Constants in Lattice QCD (1995)
Altmeyer, R. L., Gockeler, M., Horsley, R., Laermann, E., Schierholz, G., Zerwas, P. M.
We calculate the hadronic coupling constants $g_{NN\pi}$ and $g_{\rho\pi\pi}$ in QCD, including dynamical quarks in the framework of staggered fermions in the lattice approach. For the nucleon--pion...
Effective Yukawa Couplings in Noncompact Lattice QED (1995)
Goeckeler, M., Horsley, R., Rakow, P. E. L., Schierholz, G.
We investigate effective Yukawa couplings of mesons to the elementary fermions in noncompact lattice QED. The couplings are extracted from suitable fermion-antifermion-meson three-point functions...
Probing the Continuum Limit in Non-Compact QED: New Results on Large Lattices (1994)
Goeckeler, M., Horsley, R., Linke, V., Rakow, P. E. L., Schierholz, G., Stueben, H.
We present new Monte Carlo results in non-compact lattice QED with staggered fermions down to m_0 = 0.005. This extends our previous investigations on the nature of the continuum limit of QED.
Towards a Lattice Calculation of the Nucleon Structure Functions (1994)
Goeckeler, M., Horsley, R., Ilgenfritz, M., Perlt, H., Rakow, P., Schierholz, G., ...
We have initiated a programme to compute the lower moments of the unpolarised and polarised deep inelastic structure functions of the nucleon in the quenched approximation. We review our progress to...
Spectroscopy and Renormalisation Group Flow of a Lattice Nambu-Jona-Lasinio Model (1994)
Khan, A. Ali, Goeckeler, M., Horsley, R., Rakow, P. E. L., Schierholz, G., Stueben, H.
We investigate a lattice Nambu--Jona-Lasinio model both by the Monte Carlo method and Schwinger-Dyson equations. A comparison allows the discussion of finite size effects and the extrapolation to...
The Nambu-Jona-Lasinio model with staggered fermions (1994)
Khan, A. Ali, Goeckeler, M., Horsley, R., Rakow, P. E. L., Schierholz, G., Stueben, H.
We investigate the neighbourhood of the chiral phase transition in a lattice Nambu--Jona-Lasinio model, using both Monte Carlo methods and lattice Schwinger-Dyson equations.
Hadronic coupling constants in lattice QCD (1994)
Altmeyer, R., Goeckeler, M., Horsley, R., Laermann, E., Schierholz, G., Zerwas, P. M.
We report on calculations of the hadronic coupling constants $g_{\rho\pi\pi}$ and $g_{nn\pi}$ based on lattice QCD with four flavors of dynamical staggered fermions. By computing 2--point and...
The present status of non-compact lattice QED (1993)
Goeckeler, M., Horsley, R., Rakow, P. E. L., Schierholz, G., Stueben, H.
We give a 1993 update of non-compact lattice QED, in particular the chiral condensate, finite size effects and meson mass ratios. We compare descriptions of the phase transition. Our previous...
Three-point functions in noncompact lattice QED (1993)
Goeckeler, M., Horsley, R., Rakow, P. E. L., Schierholz, G.
We calculate fermion-antifermion-"meson" three-point functions in noncompact lattice QED with dynamical staggered fermions and use them to extract effective Yukawa couplings. The results are...
The pi-N Sigma term - an evaluation using staggered fermions (1993)
Altmeyer, R., Goeckeler, M., Horsley, R., Laermann, E., Schierholz, G.
A lattice calculation of the pi-N sigma term is described using dynamical staggered fermions. Preliminary results give a sea term comparable in magnitude to the valence term.
The ``Spin'' Structure of the Nucleon - a lattice investigation (1993)
Altmeyer, R., Goeckeler, M., Horsley, R., Laermann, E., Schierholz, G.
We will discuss here an indirect lattice evaluation of the baryon axial singlet current matrix element. This quantity may be related to the fraction of nucleon spin carried by the quarks. The...
The pi-N Sigma term - a lattice investigation (1993)
Altmeyer, R., Goeckeler, M., Horsley, R., Laermann, E., Schierholz, G.
A lattice calculation of the pi-N sigma term is described using dynamical staggered fermions. Preliminary results give a sea term comparable in magnitude to the valence term.
Is the Chiral Phase Transition in Non-Compact Lattice QED Driven by Monopole Condensation? (1993)
Goeckeler, M., Horsley, R., Rakow, P. E. L., Schierholz, G.
We investigate the recent conjecture that the chiral phase transition in non-compact lattice QED is driven by monopole condensation. The comparison of analytic and numerical results shows that we...
The Spin Content of the Nucleon (1992)
Altmeyer, R., Göckeler, M., Horsley, R., Laermann, E., Schierholz, G.
The fraction of the nucleon spin that is carried by the quarks, $\Delta \Sigma$, is computed in lattice QCD with dynamical staggered fermions. We obtain the value $\Delta \Sigma = 0.18 \pm 0.02$.
Altmeyer, R., Born, K. D., Goeckeler, M., Horsley, R., Laermann, E., Schierholz, G.
A numerical calculation of the lattice staggered renormalisation constants at $\beta = 5.35$, $m = 0.01$ is presented. It is seen that there are considerable non-perturbative effects present. As an...
Scaling laws, renormalization group flow and the continuum limit in non-compact lattice QED (1991)
Göckeler, M, Horsley, R, Rakow, P, Schierholz, G, Sommer, Rainer
Structure of the Pion from Full Lattice QCD. 2006-03-02 - 2006-03-09
D. Brömmel, DESY Forschung Hochenergiephysik, M. Diehl, M. Göckeler, Ph. Hägler, ...
Conference presentation
Probing Nucleon Structure on the Lattice. 2006-05-16 - 2006-05-20
M. Göckeler, P. Hägler, R. Horsley, Y. Nakamura, ...
Conference presentation
Pion Structure from Lattice QCD. 2006-10-02 - 2006-10-06
D. Brömmel, DESY Forschung Hochenergiephysik, M. Diehl, M. Göckeler, Ph. Hägler, ...
Conference presentation