First Measurement Using Elliptically Polarized Photons of the Double-Polarization Observable E for γp→pπ^{0} and γp→nπ^{+}.
作者信息
Afzal F, Spieker K, Hurck P, Abt S, Achenbach P, Adlarson P, Ahmed Z, Akondi C S, Annand J R M, Arends H J, Bashkanov M, Beck R, Biroth M, Borisov N, Braghieri A, Briscoe W J, Cividini F, Collicott C, Costanza S, Denig A, Dieterle M, Downie E J, Drexler P, Fegan S, Gardner S, Ghosal D, Glazier D I, Gorodnov I, Gradl W, Gurevich D, Heijkenskjöld L, Hornidge D, Huber G M, Kashevarov V L, Kay S J D, Korolija M, Krusche B, Lazarev A, Livingston K, Lutterer S, MacGregor I J D, Macrae R G, Manley D M, Martel P P, Miskimen R, Mocanu M, Mornacchi E, Mullen C, Neganov A, Neiser A, Oberle M, Ostrick M, Otte P B, Paudyal D, Pedroni P, Powell A, Reicherz G, Rostomyan T, Sfienti C, Sokhoyan V, Steffen O, Strakovsky I I, Strub T, Supek I, Thiel A, Thiel M, Thomas A, Usov Yu A, Wagner S, Walford N K, Watts D P, Werthmüller D, Wettig J, Witthauer L, Wolfes M, Zachariou N
机构信息
Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, D-53115 Bonn, Germany.
SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom.
出版信息
Phys Rev Lett. 2024 Mar 22;132(12):121902. doi: 10.1103/PhysRevLett.132.121902.
We report the measurement of the helicity asymmetry E for the pπ^{0} and nπ^{+} final states using, for the first time, an elliptically polarized photon beam in combination with a longitudinally polarized target at the Crystal Ball experiment at MAMI. The results agree very well with data that were taken with a circularly polarized photon beam, showing that it is possible to simultaneously measure polarization observables that require linearly (e.g., G) and circularly polarized photons (e.g., E) and a longitudinally polarized target. The new data cover a photon energy range 270-1400 MeV for the pπ^{0} final state (230-842 MeV for the nπ^{+} final state) and the full range of pion polar angles, θ, providing the most precise measurement of the observable E. A moment analysis gives a clear observation of the pη cusp in the pπ^{0} final state.
Zotero 插件