2001/12/18 by P. Bartsch, D. Baumann, J. Bermuth +40 · 3 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #nucl-ex
paper · pdf · doi:10.1103/physrevlett.88.142001
published as Phys.Rev.Lett. 88 (2002) 142001 · 5 pages, 2 figures, 2 tables
arxiv created 2001/12/18 · openalex publication_date 2002/03/26 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
In a p(\stackrel\ensuremath→e,e^\ensuremath'p)\ensuremathπ0 out-of-plane coincidence experiment at the three-spectrometer setup of the Mainz Microtron MAMI, the beam-helicity asymmetry has been precisely measured around the energy of the \ensuremathΔ(1232) resonance and Q2\phantom\rule0ex0ex=\phantom\rule0ex0ex0.2(GeV/c)2. The results are in disagreement with three up-to-date model calculations. This is interpreted as a lack of understanding of the nonresonant background, which in dynamical models is related to the pion cloud.