Experimental signature of medium modifications for rho and omega mesons in the 12 GeV p+A reactions.
/ Authors
M. Naruki, Y. Fukao, H. Funahashi, M. Ishino, H. Kanda, Masaaki Kitaguchi, S. Mihara, K. Miwa, T. Miyashita, T. Murakami
and 16 more authors
T. Nakura, F. Sakuma, M. Togawa, S. Yamada, Y. Yoshimura, H. En’yo, R. Muto, T. Tabaru, S. Yokkaichi, J. Chiba, M. Ieiri, O. Sasaki, M. Sekimoto, Kanji Tanaka, H. Hamagaki, K. Ozawa
/ Abstract
The invariant mass spectra of e+e- pairs produced in 12 GeV proton-induced nuclear reactions are measured at the KEK Proton Synchrotron. On the low-mass side of the meson peak, a significant enhancement over the known hadronic sources has been observed. The mass spectra, including the excess, are well reproduced by a model that takes into account the density dependence of the vector meson mass modification, as theoretically predicted.
Journal: Physical review letters