English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

To determine nonspherical angular momentum amplitudes in hadrons at longranges (low Q^2), data were taken for the p(\vec{e},e'p)\pi^0 reaction in theDelta region at Q^2=0.060 (GeV/c)^2 utilizing the magnetic spectrometers of theA1 Collaboration at MAMI. The results for the dominant transition magneticdipole amplitude and the quadrupole to dipole ratios at W=1232 MeV are:M_{1+}^{3/2} = (40.33 +/- 0.63_{stat+syst} +/- 0.61_{model})(10^{-3}/m_{\pi^+}),Re(E_{1+}^{3/2}/M_{1+}^{3/2}) = (-2.28 +/- 0.29_{stat+syst}+/- 0.20_{model})%, and Re(S_{1+}^{3/2}/M_{1+}^{3/2}) = (-4.81 +/-0.27_{stat+syst} +/- 0.26_{model})%. These disagree with predictions ofconstituent quark models but are in reasonable agreement with latticecalculations with non-linear (chiral) pion mass extrapolations, with chiraleffective field theory, and with dynamical models with pion cloud effects.These results confirm the dominance, and general Q^2 variation, of the pioniccontribution at large distances.Comment: 6 pages, 3 figures, 1 tabl

Lowest- Q2 measurement of the γp → Δ reaction: Probing the pionic contribution