title: Electromagnetic nucleon-to-delta transition in chiral effective-field theory.
abstract: We perform a relativistic chiral effective-field theory calculation of pion electroproduction off the nucleon (e- N --> e- N(pi)) in the delta(1232)-resonance region. After fixing the three low-energy constants, corresponding to the magnetic (M1), electric (E2), and Coulomb (C2) gammaNdelta couplings, our calculation provides a prediction for the momentum transfer and pion-mass dependence of the gammaNdelta form factors. The prediction for the pion-mass dependence resolves the discrepancy between the recent lattice QCD results and the experimental value for the "C2/M1 ratio" at low Q2.
authors.affiliation: Physics Department, The College of William & Mary, Williamsburg, Virginia 23187, USA. vlad@jlab.org
authors.forename: Vladimir
authors.initials: V
authors.lastname: Pascalutsa
authors.forename: Marc
authors.initials: M
authors.lastname: Vanderhaeghen