Measurement of the transverse target and beam-target asymmetries in η meson photoproduction at MAMI

C S Akondi; J R M Annand; H J Arends; R Beck; A Bernstein; N Borisov; A Braghieri; W J Briscoe; S Cherepnya; C Collicott; S Costanza; E J Downie; M Dieterle; A Fix; L V Fil'kov; S Garni; D I Glazier; W Gradl; G Gurevich; P Hall Barrientos; D Hamilton; D Hornidge; D Howdle; G M Huber; V L Kashevarov; I Keshelashvili; R Kondratiev; M Korolija; B Krusche; A Lazarev; V Lisin; K Livingston; I J D MacGregor; J Mancel; D M Manley; P Martel; E F McNicoll; W Meyer; D Middleton; R Miskimen; A Mushkarenkov; B M K Nefkens; A Neganov; A Nikolaev; M Oberle; M Ostrick; H Ortega; P Ott; P B Otte; B Oussena; P Pedroni; A Polonski; V V Polyanski; S Prakhov; G Reicherz; T Rostomyan; A Sarty; S Schumann; O Steffen; I I Strakovsky; Th Strub; I Supek; L Tiator; A Thomas; M Unverzagt; Yu A Usov; D P Watts; D Werthmüller; L Witthauer; M Wolfes; A2 Collaboration at MAMI

doi:10.1103/PhysRevLett.113.102001

Measurement of the transverse target and beam-target asymmetries in η meson photoproduction at MAMI

Phys Rev Lett. 2014 Sep 5;113(10):102001. doi: 10.1103/PhysRevLett.113.102001. Epub 2014 Sep 4.

Authors

C S Akondi¹, J R M Annand², H J Arends³, R Beck⁴, A Bernstein⁵, N Borisov⁶, A Braghieri⁷, W J Briscoe⁸, S Cherepnya⁹, C Collicott¹⁰, S Costanza⁷, E J Downie¹¹, M Dieterle¹², A Fix¹³, L V Fil'kov⁹, S Garni¹², D I Glazier¹⁴, W Gradl³, G Gurevich¹⁵, P Hall Barrientos¹⁶, D Hamilton², D Hornidge¹⁷, D Howdle², G M Huber¹⁸, V L Kashevarov¹⁹, I Keshelashvili¹², R Kondratiev¹⁵, M Korolija²⁰, B Krusche¹², A Lazarev⁶, V Lisin¹⁵, K Livingston², I J D MacGregor², J Mancel², D M Manley¹, P Martel²¹, E F McNicoll², W Meyer²², D Middleton²³, R Miskimen²⁴, A Mushkarenkov²⁵, B M K Nefkens²⁶, A Neganov⁶, A Nikolaev⁴, M Oberle¹², M Ostrick³, H Ortega³, P Ott³, P B Otte³, B Oussena¹¹, P Pedroni⁷, A Polonski¹⁵, V V Polyanski⁹, S Prakhov²⁶, G Reicherz²², T Rostomyan¹², A Sarty¹⁰, S Schumann²⁷, O Steffen³, I I Strakovsky⁸, Th Strub¹², I Supek²⁰, L Tiator³, A Thomas³, M Unverzagt³, Yu A Usov⁶, D P Watts¹⁶, D Werthmüller¹², L Witthauer¹², M Wolfes³; A2 Collaboration at MAMI

Affiliations

¹ Kent State University, Kent, Ohio 44242-0001, USA.
² SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
³ Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany.
⁴ Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, D-53115 Bonn, Germany.
⁵ Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
⁶ Joint Institute for Nuclear Research, 141980 Dubna, Russia.
⁷ INFN Sezione di Pavia, I-27100 Pavia, Italy.
⁸ The George Washington University, Washington, DC 20052-0001, USA.
⁹ Lebedev Physical Institute, 119991 Moscow, Russia.
¹⁰ Department of Astronomy and Physics, Saint Marys University, Halifax, Nova Scotia B3H 3C3, Canada.
¹¹ Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany and The George Washington University, Washington, DC 20052-0001, USA.
¹² Departement für Physik, University of Basel, CH-4056 Basel, Switzerland.
¹³ Laboratory of Mathematical Physics, Tomsk Polytechnic University, 634034 Tomsk, Russia.
¹⁴ SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom and SUPA School of Physics, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom.
¹⁵ Institute for Nuclear Research, 125047 Moscow, Russia.
¹⁶ SUPA School of Physics, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom.
¹⁷ Mount Allison University, Sackville, New Brunswick E4L 1E6, Canada.
¹⁸ University of Regina, Regina, Saskatchewan S4S 0A2, Canada.
¹⁹ Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany and Lebedev Physical Institute, 119991 Moscow, Russia.
²⁰ Rudjer Boskovic Institute, HR-10000 Zagreb, Croatia.
²¹ Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA and University of Massachusetts, Amherst, Massachusetts 01003, USA.
²² Institut für Experimentalphysik, Ruhr-Universität, D-44780 Bochum, Germany.
²³ Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany and Mount Allison University, Sackville, New Brunswick E4L 1E6, Canada.
²⁴ University of Massachusetts, Amherst, Massachusetts 01003, USA.
²⁵ INFN Sezione di Pavia, I-27100 Pavia, Italy and University of Massachusetts, Amherst, Massachusetts 01003, USA.
²⁶ University of California Los Angeles, Los Angeles, California 90095-1547, USA.
²⁷ Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany and Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

PMID: 25238349
DOI: 10.1103/PhysRevLett.113.102001

Abstract

We present new data for the transverse target asymmetry T and the very first data for the beam-target asymmetry F in the γ[over →]p[over →]→ηp reaction up to a center-of-mass energy of W=1.9 GeV. The data were obtained with the Crystal-Ball/TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. All existing model predictions fail to reproduce the new data indicating a significant impact on our understanding of the underlying dynamics of η meson photoproduction. The peculiar nodal structure observed in existing T data close to threshold is not confirmed.