The -beam asymmetry in the photoproduction of negative pions on quasi-free neutrons in a deuterium target was measured at the Grenoble Anneau Accelerateur Laser in the energy interval MeV and over a wide angular range, using polarized and tagged photons. Results are compared with recent partial-wave analyses.
DOI:https://doi.org/10.1103/PhysRevC.82.045209
©2010 American Physical Society
Difference between the Fermi momentum reconstruction at the th step in the recursive method and at step 0 for the signal (solid line) and for the concurrent channels (dashed line) in the simulation.
Reuse & PermissionsFermi momentum of the neutron calculated before (upper curve) and after (lower curve) the cuts.
Reuse & PermissionsFermi momentum (dashed line) of the neutron after the cuts (data) and Fermi momentum (solid line) generated using the Paris potential.
Reuse & PermissionsBeam polarization asymmetries for versus pion center-of-mass scattering angle. The photon energy is shown. Solid (dash-dotted) lines correspond to the SAID MA09 (SP09 [26]) solution. Dotted lines give the MAID2007 [27] predictions. Experimental data are from the current (filled circles) and previous [24, 25] (open circles) measurements. Plotted points from previously published experimental data are data points within 4 MeV of the photon energy indicated in each panel. Plotted uncertainties are statistical. In the last panel the asymmetries are plotted versus the -ray energy for the c.m. angle of 128. The MA09 includes in its database the GRAAL asymmetries for the and [12] reactions. SP09 and MAID2007 do not include these data.
Reuse & PermissionsMultipole amplitudes from to MeV for isospin 1/2. Solid (dashed) lines correspond to the real (imaginary) part of the MA09 solution. Dashed-dotted (dotted) lines give the real (imaginary) part of the SP09 [26] solution. Vertical arrows indicate the position of the considered resonance, while horizontal bars show full and partial widths for associated with the SAID solution SP06 [28].
Reuse & Permissions
