In-medium modifications of the omega meson near the production threshold

ISSN
1434-601X
1434-6001
Date Issued
2013
Author(s)
Thiel, M.
Metag, V.
Bartolome, P. Aguar
Akasoy, L. K.
Annand, J. R. M.
Arends, H. J.
Bantawa, K.
Beck, R.
Bekrenev, V.
Berghaeuser, H.
Braghieri, A.
Briscoe, W. J.
Brudvik, J.
Cherepnya, S.
Dieterle, M.
Downie, E. J.
Drexler, P.
Fil'kov, L. V.
Glazier, D. I.
Gregor, R.
Heid, E.
Hornidge, D.
Jude, T. C.
Kashevarov, V. L.
Keshelashvili, I.
Kondratiev, R.
Korolija, M.
Kotulla, M.
Krusche, B.
Kulbardis, A.
Lemmer, Boris
Lisin, V.
Livingston, K.
MacGregor, I. J. D.
Maghrbi, Y.
Mancell, J.
Manley, D. M.
Martinez, M.
McGeorge, J. C.
McNicoll, E. F.
Middleton, D. G.
Mushkarenkov, A.
Nanova, M.
Nefkens, B. M. K.
Nikolaev, A.
Novotny, R. W.
Ostrick, M.
Pedroni, P.
Pheron, F.
Polonski, A.
Prakhov, S. N.
Robinson, J.
Rosner, G.
Rostomyan, T.
Sikora, M. H.
Starostin, A.
Supek, I.
Thomas, Andy
Unverzagt, M.
Watts, D. P.
Weil, J.
Werthmueller, D.
Zamboni, I.
DOI
10.1140/epja/i2013-13132-6
Abstract
The in-medium properties of the omega meson were investigated at the MAMI-C electron accelerator using the Crystal Ball/TAPS detector system to identify omega mesons through their omega -> pi(0)gamma decay channel. Two solid targets (C, Nb) and a LH2 target as a reference have been used. In the energy range 900 to 1300 MeV the omega lineshapes for the different nuclei are compared and a broadening of the omega signal for the niobium target is observed in comparison to the liquid-hydrogen target. In a second analysis the omega momentum distributions for the solid targets are determined for 50 MeV/c wide bins. For both analyses a comparison to transport calculations shows that the data are consistent with an in-medium modification by collisional broadening, as observed by transparency ratio measurements.