Physics Letters B (Nov 2015)

Measurement of double polarisation asymmetries in ω-photoproduction

  • H. Eberhardt,
  • T.C. Jude,
  • H. Schmieden,
  • A.V. Anisovich,
  • B. Bantes,
  • D. Bayadilov,
  • R. Beck,
  • Yu. Beloglazov,
  • M. Bichow,
  • S. Böse,
  • K.-Th. Brinkmann,
  • Th. Challand,
  • V. Crede,
  • F. Diez,
  • P. Drexler,
  • H. Dutz,
  • D. Elsner,
  • R. Ewald,
  • K. Fornet-Ponse,
  • St. Friedrich,
  • F. Frommberger,
  • Ch. Funke,
  • M. Gottschall,
  • A. Gridnev,
  • M. Grüner,
  • E. Gutz,
  • Ch. Hammann,
  • J. Hannappel,
  • J. Hartmann,
  • W. Hillert,
  • Ph. Hoffmeister,
  • Ch. Honisch,
  • I. Jaegle,
  • D. Kaiser,
  • H. Kalinowsky,
  • F. Kalischewski,
  • S. Kammer,
  • I. Keshelashvili,
  • V. Kleber,
  • F. Klein,
  • E. Klempt,
  • K. Koop,
  • B. Krusche,
  • M. Kube,
  • M. Lang,
  • I. Lopatin,
  • Y. Maghrbi,
  • K. Makonyi,
  • V. Metag,
  • W. Meyer,
  • J. Müller,
  • M. Nanova,
  • V. Nikonov,
  • R. Novotny,
  • D. Piontek,
  • S. Reeve,
  • G. Reicherz,
  • T. Rostomyan,
  • S. Runkel,
  • A. Sarantsev,
  • St. Schaepe,
  • Ch. Schmidt,
  • R. Schmitz,
  • T. Seifen,
  • V. Sokhoyan,
  • V. Sumachev,
  • A. Thiel,
  • U. Thoma,
  • M. Urban,
  • H. van Pee,
  • D. Walther,
  • Ch. Wendel,
  • U. Wiedner,
  • A. Wilson,
  • A. Winnebeck

DOI
https://doi.org/10.1016/j.physletb.2015.09.049
Journal volume & issue
Vol. 750, no. C
pp. 453 – 458

Abstract

Read online

The first measurements of the beam-target-helicity-asymmetries E and G in the photoproduction of ω-mesons off protons at the CBELSA/TAPS experiment are reported. E (G) was measured using circularly (linearly) polarised photons and a longitudinally polarised target. E was measured over the photon energy range from close to threshold (Eγ=1108 MeV) to Eγ=2300 MeV and G at a single energy interval of 1108<Eγ<1300 MeV. Both measurements cover the full solid angle. The observables E and G are highly sensitive to the contribution of baryon resonances, with E acting as a helicity filter in the s-channel. The new results indicate significant s-channel resonance contributions together with contributions from t-channel exchange processes. A partial wave analysis reveals strong contributions from the partial waves with spin-parity JP=3/2+,5/2+, and 3/2−.

Keywords