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We discuss the calculation of disconnected diagrams needed for determining the strange quark content of the nucleon on the lattice. We present results for the strange scalar form factor and the related parameter f_Ts, which enters into the…

High Energy Physics - Lattice · Physics 2009-01-30 Ronald Babich , Richard Brower , Michael Clark , George Fleming , James Osborn , Claudio Rebbi

The nucleon axial form factor is a dominant contribution to errors in neutrino oscillation studies. Lattice QCD calculations can help control theory errors by providing first-principles information on nucleon form factors. In these…

High Energy Physics - Lattice · Physics 2016-10-17 Aaron S. Meyer , Richard J. Hill , Andreas S. Kronfeld , Ruizi Li , James N. Simone

Flavour singlet contributions to the nucleon spin are elusive due to the fact that they cannot be determined directly in experiment but require extrapolations to the small x region. Direct calculations of these contributions are possible…

High Energy Physics - Lattice · Physics 2019-08-13 Sara Collins

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

This document is one of a series of whitepapers from the USQCD collaboration. Here, we discuss opportunities for lattice QCD in neutrino-oscillation physics, which inevitably entails nucleon and nuclear structure. In addition to discussing…

We review recent progress in hadron structure using lattice QCD simulations, with main focus in the evaluation of nucleon quantities such as the axial and tensor charges, and the spin con- tent of the nucleon, using simulations at pion…

High Energy Physics - Lattice · Physics 2015-11-24 Martha Constantinou

The quark-line disconnected diagram is a potentially important ingredient in lattice QCD calculations of the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon. It is also a notoriously difficult one to…

High Energy Physics - Lattice · Physics 2016-05-04 Bipasha Chakraborty , C. T. H. Davies , J. Koponen , G. P. Lepage , M. J. Peardon , S. M. Ryan

We present results on the disconnected contributions to three point functions entering in studies of hadron structure. We use $N_F = 2+1+1$ twisted mass fermions and give a detailed description on the results of the nucleon {\sigma}-terms,…

I describe how simulations of lattice QCD using the path integral formulation provide the two basic quantum mechanical properties of QCD, its ground state in which correlation functions are calculated, and Fock state wavefunctions between…

High Energy Physics - Lattice · Physics 2023-01-20 Rajan Gupta

Lattice QCD calculations of disconnected quark loop operators are extremely computer time-consuming to evaluate. To compute these diagrams using lattice techniques, one generally uses stochastic noise methods. These employ a randomly…

High Energy Physics - Lattice · Physics 2019-06-26 Suman Baral , Travis Whyte , Walter Wilcox , Ronald B. Morgan

The isoscalar axial-vector form factor of the nucleon plays a key role in understanding the electroweak interaction of nucleons. For the interpretation of the spin structure of the nucleon the non-singlet isoscalar axial charge is…

There are generally two types of Wick contractions in lattice QCD calculations of a correlation function --- connected and disconnected ones. The disconnected contribution is difficult to calculate and noisy, thus it is often neglected. In…

High Energy Physics - Lattice · Physics 2013-10-29 Feng-Kun Guo , Liuming Liu , Ulf-G. Meißner , Ping Wang

It is imperative that lattice QCD serve to develop our understanding of hadron structure and, where possible, to guide the interpretation of experimental data. There is now a great deal of effort directed at the calculation of the…

High Energy Physics - Lattice · Physics 2010-02-17 J. D. Ashley , D. B. Leinweber , A. W. Thomas , R. D. Young

The electromagnetic form factors of the proton and the neutron are computed within lattice QCD using simulations with quarks masses fixed to their physical values. Both connected and disconnected contributions are computed. We analyze two…

High Energy Physics - Lattice · Physics 2019-08-28 C. Alexandrou , S. Bacchio , M. Constantinou , J. Finkenrath , K. Hadjiyiannakou , K. Jansen , G. Koutsou , A. Vaquero Aviles Casco

We discuss results from lattice calculations for a few observables that are sensitive to different length scales in the high temperature phase of QCD and can give insight into its non-perturbative structure. We compare lattice results with…

High Energy Physics - Phenomenology · Physics 2008-11-26 Frithjof Karsch

We present a comprehensive analysis of the electromagnetic form factors of the nucleon from a lattice simulation with two flavors of dynamical O(a)-improved Wilson fermions. A key feature of our calculation is that we make use of an…

A few chosen nucleon properties are described from a lattice QCD perspective: the nucleon sigma term and the scalar strangeness in the nucleon; the vector form factors in the nucleon, including the vector strangeness contribution, as well…

High Energy Physics - Lattice · Physics 2015-05-28 Harvey B. Meyer

We evaluate the matrix element of $\bar{q} q$ in hadron states on a lattice. We find substantial mixing of the connected and disconnected contributions so that the lattice result that the disconnected contribution to the nucleon is large…

High Energy Physics - Lattice · Physics 2008-11-26 C. Michael , C. McNeile , D. Hepburn , UKQCD Collaboration

We present a model-independent calculation of hadron matrix elements for all dimension-six operators associated with baryon number violating processes using lattice QCD. The calculation is performed with the Wilson quark action in the…

We report results on the nucleon structure obtained from the lattice quantum chromodynamics calculation. These include the axial, electromagnetic, $\pi NN$, and scalar form factors. The calculation is carried out at $\beta = 6$ on a $16^3…

High Energy Physics - Lattice · Physics 2009-09-25 Keh-Fei Liu