Nuclear-matter modification of decay widths in the phi-->e+e- and phi-->K+K- channels.
The invariant mass spectra of phi-->K+K- are measured in 12 GeV p+A reactions in order to search for the in-medium modification of phi mesons. The observed K+K- spectra are well reproduced by the relativistic Breit-Wigner function with a combinatorial background shape in three betagamma regions between 1.0 and 3.5. The nuclear mass number dependence of the yields of the K+K- decay channel is compared to the simultaneously measured e+e- decay channel for carbon and copper targets. We parameterize the production yields as sigma(A)=sigma0Aalpha and obtain alphaphi-->K+K- -alphaphi-->e+e- to be 0.14+/-0.12. Limits are obtained for the partial decay widths of the phi mesons in nuclear matter.
Sakuma
F
F
Department of Physics, Kyoto University, Kitashirakawa Sakyo-ku, Kyoto 606-8502, Japan. sakuma@nh.scphys.kyoto-uc.j
Chiba
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En'yo
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Fukao
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Funahashi
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Hamagaki
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Ieiri
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Ishino
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Kanda
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Kitaguchi
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Mihara
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Miwa
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Miyashita
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Murakami
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Muto
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Nakura
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Naruki
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Ozawa
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Sasaki
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Sekimoto
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Tabaru
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Tanaka
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Togawa
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Yamada
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Yokkaichi
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Yoshimura
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