Observation of in-medium modifications of the ω meson
Date Issued
2005-01-01
Author(s)
Trnka, D
Anton, G
Bacelar, J C S
Bartholomy, O
Bayadilov, D
Beloglazov, Y A
Bogendörfer, R
Castelijns, R
Crede, V
Dutz, H
Ehmanns, A
Elsner, D
Ewald, R
Fabry, I
Fuchs, M
Essig, K
Funke, Ch
Gothe, R
Gregor, R
Gridnev, A B
Gutz, E
Höffgen, S
Hoffmeister, P
Horn, I
Hössl, J
Jaegle, I
Junkersfeld, J
Kalinowsky, H
Klein, Frank
Klein, Fritz
Klempt, E
Konrad, M
Kopf, B
Kotulla, M
Langheinrich, J
Löhner, H
Lopatin, I V
Lotz, J
Lugert, S
Menze, D
Messchendorp, J G
Mertens, T
Metag, V
Morales, C
Nanova, M
Novotny, R
Ostrick, M
Pant, L M
van Pee, H
Pfeiffer, M
Roy, A
Radkov, A
Schadmand, S
Schmidt, Ch
Schmieden, H
Schoch, B
Shende, S
Suft, G
Sumachev, V V
Szczepanek, T
Süle, A
Thoma, U
Varma, R
Walther, D
Weinheimer, Ch
Wendel, Ch
CBELSA/TAPS, Collaboration
DOI
10.1103/physrevlett.94.192303
Abstract
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).