Phys. Rev. Lett. 95, 232001 (2005) [4 pages]Electromagnetic Nucleon-to-Delta Transition in Chiral Effective-Field TheoryReceived 5 August 2005; published 28 November 2005 We perform a relativistic chiral effective-field theory calculation of pion electroproduction off the nucleon (e-N→e-Nπ) in the Δ(1232)-resonance region. After fixing the three low-energy constants, corresponding to the magnetic (M1), electric (E2), and Coulomb (C2) γNΔ couplings, our calculation provides a prediction for the momentum transfer and pion-mass dependence of the γNΔ 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. © 2005 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.95.232001
DOI:
10.1103/PhysRevLett.95.232001
PACS:
12.39.Fe, 13.40.Gp, 13.60.Le
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