Observation of in-medium modifications of the omega meson.

By D. Trnka, G. Anton, J. Bacelar, O. Bartholomy, D. Bayadilov, Y. Beloglazov, R. Bogendorfer, R. Castelijns, V. Crede, H. Dutz and 57 more. 2005

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The photoproduction of omega mesons on nuclei has been investigated using the Crystal Barrel/TAPS experiment at the ELSA tagged photon facility in Bonn. The aim is to study possible in-medium modifications of the omega meson via the reaction gamma+A -<omega+X -<pi(0)gamma+X-`. Results obtained for Nb are compared to a reference measurement on a LH2 target. While for recoiling, long-lived mesons (pi(0), eta, and eta(`)), which decay outside of the nucleus, a difference in the line shape for the two data samples is not observed, we find a significant enhancement towards lower masses for omega mesons produced on the Nb target. For momenta less than 500 MeV/c an in-medium omega meson mass of M-medium=[722(-4)(+4)(stat)(-5)(+35)(syst)] MeV/c(2) has been deduced at an estimated average nuclear density of 0.6 rho(0).

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/67ad559bba893f2a4f52e103fd60327f6b0e4b2d