Transparency ratio in γ A -> η' A ' and the in-medium η ' width

The photoproduction of η′η′-mesons off different nuclei has been measured with the CBELSA/TAPS detector system for incident photon energies between 15002200 MeV. The transparency ratio has been deduced and compared to theoretical calculations describing the propagation of η′η′-mesons in nuclei. The comparison indicates a width of the η′η′-meson of the order of Γ=1525 MeVΓ=1525 MeV at ρ=ρ0ρ=ρ0 for an average momentum pη′=1050 MeV/cpη′=1050 MeV/c, at which the η′η′-meson is produced in the nuclear rest frame. The inelastic η′Nη′N cross section is estimated to be 310 mb. Parameterizing the photoproduction cross section of η′η′-mesons by σ(A)=σ0Aασ(A)=σ0Aα, a value of α=0.84±0.03α=0.84±0.03 has been deduced.

M. Nanova1, V. Metag1, A. Ramos2, E. Oset3, I. Jaegle4,a, K. Makonyi1, K. Brinkmann5,O. Bartholomy5, D. Bayadilov5,6, Y.A. Beloglazov6, V. Crede5,b, H. Dutz5, A. Ehmanns5,D. Elsner7, K. Essig5, R. Ewald7, I. Fabry5, M. Fuchs5, Ch. Funke5, R. Gregor1,A.B. Gridnev6, E. Gutz5, S. H¨offgen5, P. Hoffmeister5, I. Horn5, J. Junkersfeld5,H. Kalinowsky5, Frank Klein7, Friedrich Klein7, E. Klempt5, M. Konrad7, B. Kopf8,9,B. Krusche4, J. Langheinrich7,9, H. L¨ohner10, I.V. Lopatin6, J. Lotz5, S. Lugert1,D. Menze7, T. Mertens4, J.G. Messchendorp10, C. Morales7, R. Novotny1, M. Ostrick7,c,L.M. Pant1,d, H. van Pee5, M. Pfeiffer1, A. Roy1,e, A. Radkov6, S. Schadmand1,f ,Ch. Schmidt5, H. Schmieden7, B. Schoch7, A. S¨ule7, V. V. Sumachev6,T. Szczepanek5, U. Thoma5, D. Trnka1, R. Varma1,g, D. Walther5, Ch. Wendel5(The CBELSA/TAPS Collaboration)

Ramos, A., Oset, E.,... [et al.] fins 61 autors