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We present results for the nucleon electromagnetic form factors, including the momentum transfer dependence and derived quantities (charge radii and magnetic moment). The analysis is performed using O(a) improved Wilson fermions in Nf=2 QCD…

高能物理 - 格点 · 物理学 2015-09-30 S. Capitani , M. Della Morte , D. Djukanovic , G. von Hippel , J. Hua , B. Jäger , B. Knippschild , H. B. Meyer , T. D. Rae , H. Wittig

We present results for the strange contribution to the electromagnetic form factors of the nucleon computed on the CLS ensembles with $N_f=2+1$ flavors of $\mathcal{O}(a)$-improved Wilson fermions and an $\mathcal{O}(a)$-improved vector…

高能物理 - 格点 · 物理学 2019-12-10 Dalibor Djukanovic , Konstantin Ottnad , Jonas Wilhelm , Hartmut Wittig

We present preliminary results on the electromagnetic form factors and axial charge of the nucleon from ensembles generated by the CLS effort with $N_\mathrm{f}=2+1$ flavours of non-perturbatively $\mathrm{O}(a)$-improved Wilson fermions…

高能物理 - 格点 · 物理学 2015-11-25 Dalibor Djukanovic , Tim Harris , Georg von Hippel , Parikshit Junnarkar , Harvey B. Meyer , Hartmut Wittig

We present updated results for the nucleon axial charge and electromagnetic (EM) form factors, which include a significant increase in statistics for all ensembles (up to 4000 measurements), as well as the addition of ensembles with pion…

高能物理 - 格点 · 物理学 2014-04-09 B. Jäger , T. D. Rae , S. Capitani , M. Della Morte , D. Djukanovic , G. von Hippel , B. Knippschild , H. B. Meyer , H. Wittig

We present results for the isoscalar electromagnetic form factors of the nucleon computed on the Coordinated Lattice Simulations (CLS) ensembles with $N_\mathrm{f} = 2 + 1$ flavors of $\mathcal{O}(a)$-improved Wilson fermions and an…

Among the sources of systematic error in nucleon structure calculations is contamination from unwanted excited states. In order to measure this systematic error, we vary the operator insertion time and source-sink separation independently.…

高能物理 - 格点 · 物理学 2012-03-23 Jeremy Green , Stefan Krieg , John Negele , Andrew Pochinsky , Sergey Syritsyn

We present updated results on the nucleon electromagnetic form factors and axial coupling calculated using CLS ensembles with $N_\mathrm{f}=2+1$ dynamical flavours of Wilson fermions. The measurements are performed on large, fine lattices…

高能物理 - 格点 · 物理学 2017-03-01 Dalibor Djukanovic , Tim Harris , Georg von Hippel , Parikshit Junnarkar , Harvey B. Meyer , Hartmut Wittig

We study the ability of a variety of fitting techniques to extract the ground state matrix elements of the vector current from ratios of nucleon three- and two-point functions that contain contaminations from excited states. Extending our…

高能物理 - 格点 · 物理学 2014-11-19 G. M. von Hippel , S. Capitani , D. Djukanovic , J. Hua , B. Jäger , P. Junnarkar , H. B. Meyer , T. D. Rae , H. Wittig

One of the most challenging tasks in lattice calculations of baryon form factors is the analysis and control of excited-state contaminations. Taking the isovector axial form factors of the nucleon as an example, both a dispersive…

高能物理 - 格点 · 物理学 2021-12-01 Harvey B. Meyer , Konstantin Ottnad , Tobias Schulz

We present results for the electromagnetic form factors of the proton and neutron computed on the Coordinated Lattice Simulations (CLS) ensembles with $N_f = 2 + 1$ flavors of $\mathcal{O}(a)$-improved Wilson fermions and an…

高能物理 - 格点 · 物理学 2023-01-10 Miguel Salg , Dalibor Djukanovic , Georg von Hippel , Harvey B. Meyer , Konstantin Ottnad , Hartmut Wittig

We present preliminary results on the axial form factor $G_A(Q^2)$ and the induced pseudoscalar form factor $G_P(Q^2)$ of the nucleon. A systematic analysis of the excited-state contributions to form factors is performed on the CLS ensemble…

高能物理 - 格点 · 物理学 2014-11-24 P. M. Junnarkar , S. Capitani , D. Djukanovic , G. von Hippel , J. Hua , B. Jäger , H. B. Meyer , T. D. Rae , H. Wittig

We present results on the nucleon electromagnetic form factors from Lattice QCD at momentum transfer up to about $12$~GeV$^2$. We analyze two gauge ensembles with the Wilson-clover fermion action, a lattice spacing of $a\approx 0.09$~fm and…

We present the nucleon axial and electromagnetic form factors using \Nf{2}{1}{1} ensembles of twisted mass fermions with clover improvement and with masses tuned to their physical values. Excited state effects are studied using several…

We present lattice QCD calculations of nucleon electromagnetic form factors using pion masses $m_\pi$ = 149, 202, and 254 MeV and an action with clover-improved Wilson quarks coupled to smeared gauge fields, as used by the…

高能物理 - 格点 · 物理学 2014-11-20 J. R. Green , J. W. Negele , A. V. Pochinsky , S. N. Syritsyn , M. Engelhardt , S. Krieg

We present a lattice calculation of the nucleon iso-vector axial and induced pseudoscalar form factors on the CLS ensembles using $N_{\rm f}=2$ dynamical flavours of non-perturbatively $\mathcal{O}(a)$-improved Wilson fermions and an…

We discuss the extraction of heavy-light pseudo-scalar to light pseudo-scalar decay form factors from finite time correlation functions. We place particular emphasis on the contamination from excited states employing summed ratios and input…

We perform a high-statistics precision calculation of nucleon matrix elements using an open sink method allowing us to explore a wide range of sink-source time separations. In this way the influence of excited states of nucleon matrix…

We present a nucleon structure analysis including local isovector charges as well as twist-2 operator insertions. Computations are performed on CLS ensembles with $N_f=2+1$ Wilson fermions, covering four values of the lattice spacing and…

高能物理 - 格点 · 物理学 2018-11-27 Konstantin Ottnad , Tim Harris , Harvey Meyer , Georg von Hippel , Jonas Wilhelm , Hartmut Wittig

We present results for the nucleon electromagnetic and axial form factors using an N$_f$=2 twisted mass fermion ensemble with pion mass of about 131 MeV. We use multiple sink-source separations to identify excited state contamination.…

Form factors of the nucleon have been extracted from experiment with high precision. However, lattice calculations have failed so far to reproduce the observed dependence of form factors on the momentum transfer. We have embarked on a…

高能物理 - 格点 · 物理学 2011-04-20 Stefano Capitani , Michele Della Morte , Bastian Knippschild , Hartmut Wittig
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