218 research outputs found
Novel applications of Lattice QCD: Parton distribution functions, proton charge radius and neutron electric dipole moment
We briefly discuss the current status of lattice QCD simulations and review
selective results on nucleon observables focusing on recent developments in the
lattice QCD evaluation of the nucleon form factors and radii, parton
distribution functions and their moments, and the neutron electric dipole
moment. Nucleon charges and moments of parton distribution functions are
presented using simulations generated at physical values of the quark masses,
while exploratory studies are performed for the parton distribution functions
and the neutron electric dipole moment at heavier than physical value of the
pion mass.Comment: Plenary talk at XII Quark Confinement, 29 August - 3 September, 2016,
Thessaloniki, Greece, 20 pages, 21 figure
Hadron structure from lattice QCD - outlook and future perspectives
We review results on hadron structure using lattice QCD simulations with pion
masses close or at to the physical value. We pay particular attention to recent
successes on the computation of the mass of the low-lying baryons and on the
challenges involved in evaluating energies of excited states and resonance
parameters, as well as, in studies of nucleon structure.Comment: Corrected figure 1 and added references. Conference proceedings, 10
pages and 8 figures. Plenary talk presented at the 20th Particle and Nuclear
International Conference (PANIC 2014), 25-29 Hamburg, German
Nucleon structure from lattice QCD - recent achievements and perspectives
We present recent developments in lattice QCD simulations as applied in the
study of hadron structure. We discuss the challenges and perspectives in the
evaluation of benchmark quantities such as the nucleon axial charge and the
isovector parton momentum fraction, as well as, in the computation of the
nucleon -terms, which involve the calculation of disconnected quark
loop contributions.Comment: Invited talk at the 13th International Conference on Meson-Nucleon
Physics and the Structure of the Nucleon (MENU 2013), Rome, Italy, 30 Sept-
Oct. 4, 2013. 6 pages, 10 figure
The volume dependence of spectral weights and the pentaquark state
Before studying the pentaquark system we examine the spectral weights of the
two lowest scattering states in the two-pion system in the isospin I=2 channel
on lattices of size , and at
in the quenched theory. We find that the spectral weights scale
with the volume for large time separations. Therefore very accurate data are
necessary in order that the spectral weights determined on different volumes
yield a ratio that is precise enough to distinguish a scattering state from a
single particle state. The pentaquark system is studied on the same lattices
and scaling of the spectral weights of the low lying state is investigated. The
accuracy of the results obtained for the scaling of spectral weights do not
allow us to exclude a pentaquark resonance.Comment: 6 pages, 7 Figures, presented at Lattice 2005 (Hadron sprectrum),
uses PoS.cl
Nucleon to and form factors in Lattice QCD
We present recent lattice QCD results on the electroweak nucleon to
transition and form factors using dynamical fermion gauge
configurations with a lowest pion mass of about 300 MeV, with special emphasis
in the determination of the sub-dominant quadrupole and electromagnetic form factors.Comment: Invited talk presented at the 8th International Workshop on the
Physics of Excited Nucleons May 17-20, 2011, Thomas Jefferson National
Accelerator Facility Newport News, Virginia USA. 6 pages and 6 figure
Multigrid accelerated simulations for Twisted Mass fermions
Simulations at physical quark masses are affected by the critical slowing
down of the solvers. Multigrid preconditioning has proved to deal effectively
with this problem. Multigrid accelerated simulations at the physical value of
the pion mass are being performed to generate and
gauge ensembles using twisted mass fermions. The adaptive aggregation-based
domain decomposition multigrid solver, referred to as DD-AMG method, is
employed for these simulations. Our simulation strategy consists of an hybrid
approach of different solvers, involving the Conjugate Gradient (CG),
multi-mass-shift CG and DD-AMG solvers. We present an analysis of the
multigrid performance during the simulations discussing the stability of the
method. This significant speeds up the Hybrid Monte Carlo simulation by more
than a factor at physical pion mass compared to the usage of the CG solver.Comment: 8 pages, 5 figures, proceedings for LATTICE 201
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