Nucleon electromagnetic form factors from lattice QCD using a nearly physical pion mass

We present lattice QCD calculations of nucleon electromagnetic form factors using pion masses m_π=149, 202, and 254 MeV and an action with clover-improved Wilson quarks coupled to smeared gauge fields, as used by the Budapest-Marseille-Wuppertal Collaboration. Particular attention is given to the removal of the effects of excited-state contamination by calculations at three source-sink separations and the use of the summation and generalized pencil-of-function methods. The combination of a calculation at the nearly physical mass m_π=149 MeV in a large spatial volume (m_πLₛ=4.2) and the removal of excited-state effects yields agreement with experiment for the electric and magnetic form factors GE(Q²) and GM(Q²) up to Q²=0.5 GeV².