Nucleon electromagnetic form factors using lattice simulations at the physical point

• Published in: arXiv.org
• Main Authors: Alexandrou, Constantia, Constantinou, Martha, Hadjiyiannakou, Kyriakos, Jansen, Karl, Kallidonis, Christos, Koutsou, Giannis, Alejandro Vaquero Aviles-Casco
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 20.09.2017
• Subjects: Dependence; Dipoles; Fermions; Form factors; Magnetic moments; Physics - High Energy Physics - Lattice; Product design; Quantum chromodynamics; Upper bounds
• DOI: 10.48550/arxiv.1706.00469

We present results for the nucleon electromagnetic form factors using an ensemble of maximally twisted mass clover-improved fermions with pion mass of about 130 MeV. We use multiple sink-source separations and three analysis methods to probe ground-state dominance. We evaluate both the connected and disconnected contributions to the nucleon matrix elements. We find that the disconnected quark loop contributions to the isoscalar matrix elements are small, giving an upper bound of up to 2\(\%\) of the connected contribution and smaller than its statistical error. We present results for the isovector and isoscalar electric and magnetic Sachs form factors and the corresponding proton and neutron form factors. By fitting the momentum dependence of the form factors to a dipole form or to the z-expansion we extract the nucleon electric and magnetic radii, as well as, the magnetic moment. We compare our results to experiment as well as to other recent lattice QCD calculations.