Photon asymmetry measurements of $\overrightarrow{\gamma}p \rightarrow \pi^{0} p$ γ → p → π 0 p for $E_{\gamma}=$ E γ = 320-650 MeV

Abstract

Abstract. High-statistics measurements of the photon asymmetry Σ for the γp → π 0 p reaction have been made in the center-of-mass energy range W = 1214-1450 MeV. The data were measured with the MAMI A2 real photon beam and Crystal Ball/TAPS detector systems in Mainz, Germany. The results significantly improve the existing world data and are shown to be in good agreement with previous measurements, and with the MAID, SAID, and Bonn-Gatchina predictions. We have also combined the photon asymmetry results with recent cross-section measurements from Mainz to calculate the profile functions,Σ (= σ 0Σ),

New graphical criterion for the selection of complete sets of polarization observables and its application to single-meson photoproduction as well as electroproduction

“…Still, when evaluating all the different cases possible for a particular consistency-relation ( 8), the ζ-angles have a great power for resolving discrete ambiguities, or equivalently for removing degenerate pairs of equations. Thus, one has to carefully keep track of the signs of the ζ's appearing in equations ( 17) to (20), when devising a graphical criterion.…”

“…For the spectroscopy of baryons [1,2] in particular, most experimental activities in the recent years have taken place at facilities capable of measuring reactions induced by electromagnetic probes. Well-known experiments, all capable of measuring the photoproduction of one or several pseudoscalar mesons (as well as vector mesons), are the CBELSA/TAPS experiment at Bonn [3][4][5][6][7][8], CLAS at JLab (Newport News) [9][10][11][12][13][14][15], A2 at MAMI (Mainz) [16][17][18][19][20][21][22][23][24], and LEPS at SPring-8 (Hyōgo Prefecture) [25,26]. The GlueX Collaboration has started exploring completely new kinematic regimes for single-meson photoproduction recently [27][28][29].…”

“…The expressions for the ambiguities(17) to(20), as derived in appendix A, are formally a bit different compared to those of reference[73]. However, the most important features of the derived ambiguities (i.e.…”