Investigation of the conjectured nucleon deformation at low momentum transfer

N. F. Sparveris, Ricardo Alarcon, A. M. Bernstein, W. Bertozzi, T. Botto, P. Bourgeois, J. Calarco, F. Casagrande, M. O. Distler, K. Dow, M. Farkondeh, S. Georgakopoulos, S. Gilad, R. Hicks, M. Holtrop, A. Hotta, X. Jiang, A. Karabarbounis, J. Kirkpatrick, S. KowalskiR. Milner, R. Miskimen, I. Nakagawa, C. N. Papanicolas, A. J. Sarty, Y. Sato, S. Širca, J. Shaw, E. Six, S. Stave, E. Stiliaris, T. Tamae, G. Tsentalovich, C. Tschalaer, W. Turchinetz, Z. L. Zhou, T. Zwart

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114 Scopus citations


We report new precise H(e, e′p)-π0 measurements at the Δ(1232) resonance at Q2 = 0.127 (GeV/c)2 obtained at the MIT-Bates out-of-plane scattering facility which are particularly sensitive to the transverse electric amplitude (E2) of the γ*N → Δ transition. The new data have been analyzed together with those of earlier measurements to yield precise quadrupole to dipole amplitude ratios: Re(E 1+3/2/M1+3/2) = (-2.3 ± 0.3stat+syst ± 0.6model)% and Re(S 1+3/2/M1+3/2) = (-6.1 ± 0.2stat+syst ± 0.5model)% for M1+ 3/2 = (41.4 ± 0.3stat+syst ± 0.4 model)(10-3/mπ+). The derived amplitudes give credence to the conjecture of deformation in hadrons favoring, at low Q2, the dominance of mesonic effects.

Original languageEnglish (US)
Article number022003
JournalPhysical Review Letters
Issue number2
StatePublished - Jan 21 2005

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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