Eur. Phys. J. A (2007) 33: 169-184
https://doi.org/10.1140/epja/i2007-10439-9

Regular Article - Experimental Physics

Measurement of η photoproduction on the proton from threshold to 1500 MeV

¹ LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, 53 avenue des Martyrs, 38026, Grenoble, France
² Dipartimento di Fisica, Università di Roma “Tor Vergata”, via della Ricerca Scientifica 1, I-00133, Roma, Italy
³ Dipartimento di Fisica Sperimentale, Università di Torino, via P. Giuria, I-00125, Torino, Italy
⁴ Laboratori Nazionali di Frascati, INFN, via E. Fermi 40, I-00044, Frascati, Italy
⁵ Laboratori Nazionali del Sud, INFN, via Santa Sofia 44, I-95123, Catania, Italy
⁶ Sezione di Catania, INFN, via Santa Sofia 64, I-95123, Catania, Italy
⁷ Sezione di Genova, INFN, via Dodecanneso 33, I-16146, Genova, Italy
⁸ Sezione di Roma, INFN, piazzale Aldo Moro 2, I-00185, Roma, Italy
⁹ Sezione di Roma “Tor Vergata”, INFN, via della Ricerca Scientifica 1, I-00133, Roma, Italy
¹⁰ Sezione di Torino, INFN, I-10125, Torino, Italy
¹¹ Istituto Superiore di Sanità, viale Regina Elena 299, I-00161, Roma, Italy
¹² Dipartimento di Fisica ed Astronomia, Università di Catania, via Santa Sofia 64, I-95123, Catania, Italy
¹³ Institute for Nuclear Research, 117312, Moscow, Russia
¹⁴ IPNO, Université Paris-Sud 11, CNRS/IN2P3, 15 rue Georges Clémenceau, 91406, Orsay, France
¹⁵ Dipartimento di Fisica, Università di Messina, salita Sperone, I-98166, Messina, Italy

^* e-mail: lleres@lpsc.in2p3.fr

Received: 16 May 2007
Accepted: 13 July 2007
Published online: 13 August 2007

Abstract

Beam asymmetry and differential cross-section for the reaction γp → ηp were measured from production threshold to 1500MeV photon laboratory energy. The two dominant neutral decay modes of the η -meson, η → 2γ and η → 3π⁰ , were analyzed. The full set of measurements is in good agreement with previously published results. Our data were compared with three models. They all fit satisfactorily the results but their respective resonance contributions are quite different. The possible photoexcitation of a narrow state N(1670) was investigated and no evidence was found.