A new method for suppressing excited-state contaminations on the nucleon form factors


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 representation and a calculation in chiral effective field theory show that the excited-state contributions become dominant at fixed source-sink separation when the axial current is spatially distant from the nucleon source location. We address this effect with a new method in which the axial current is localized by a Gaussian wave-packet and apply it on a CLS ensemble with Nf=2+1N_f=2+1 flavors of O(aa) improved Wilson fermions with a pion mass of mΟ€=200 m_\pi=200\,MeV.Comment: 7 pages, 6 figures, 1 table, Proceedings for the 36th Annual International Symposium on Lattice Field Theory, 22-28 July 2018, Michigan State University, East Lansing, Michigan, US

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