Momentum dependence of the imaginary part of the ω - and η -nucleus optical potential

CBELSA/TAPS Collaboration The CBELSA/TAPS Collaboration, S. Friedrich, M. Nanova, V. Metag, F. N. Afzal, D. Bayadilov, B. Bantes, R. Beck, M. Becker, S. Böse, K. T. Brinkmann, V. Crede, P. Drexler, H. Eberhardt, D. Elsner, F. Frommberger, Ch Funke, M. Gottschall, M. Grüner, E. GutzCh Hammann, J. Hannappel, J. Hartmann, W. Hillert, Ph Hoffmeister, Ch Honisch, T. Jude, D. Kaiser, F. Kalischewski, I. Keshelashvili, F. Klein, K. Koop, B. Krusche, M. Lang, K. Makonyi, F. Messi, J. Müller, J. Müllers, D. M. Piontek, T. Rostomyan, D. Schaab, Ch Schmidt, H. Schmieden, R. Schmitz, T. Seifen, V. Sokhoyan, C. Sowa, A. Thiel, D. Walther, A. Wilson

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskriftPeer review


The photoproduction of ω and η mesons off carbon and niobium nuclei has been measured as a function of the meson momentum for incident photon energies of 1.2-2.9GeV at the electron accelerator ELSA. The mesons have been identified via the ω → π0 γ → 3 γ and η → π0η → 6 γ decays, respectively, registered with the CBELSA/TAPS detector system. From the measured meson momentum distributions the momentum dependence of the transparency ratio has been determined for both mesons. Within a Glauber analysis the in-medium ω and η widths and the corresponding absorption cross sections have been deduced as a function of the meson momentum. The results are compared to recent theoretical predictions for the in-medium ω width and η-N absorption cross sections. The energy dependence of the imaginary part of the ω- and η-nucleus optical potential has been extracted. The finer binning of the present data compared to the existing data allows a more reliable extrapolation towards the production threshold. The modulus of the imaginary part of the η-nucleus potential is found to be about three times smaller than recently determined values of the real part of the η-nucleus potential, which makes the η meson a suitable candidate for the search for meson-nucleus bound states. For the ω meson, the modulus of the imaginary part near threshold is comparable to the modulus of the real part of the potential. As a consequence, only broad structures can be expected, which makes the observation of ω mesic states very difficult experimentally.

TidskriftEuropean Physical Journal A
StatusPublished - 2016 sep. 1
Externt publiceradJa


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