Results of a search for the hc(P11) state of charmonium in the ηcγ and J/ψπ0 decay modes

M. Andreotti, S. Bagnasco, W. Baldini, D. Bettoni, G. Borreani, A. Buzzo, R. Calabrese, R. Cester, G. Cibinetto, P. Dalpiaz, G. Garzoglio, K. E. Gollwitzer, M. Graham, M. Hu, D. Joffe, J. Kasper, G. Lasio, M. Lo Vetere, E. Luppi, M. MacrìM. Mandelkern, F. Marchetto, M. Marinelli, E. Menichetti, Z. Metreveli, R. Mussa, M. Negrini, M. M. Obertino, M. Pallavicini, N. Pastrone, C. Patrignani, T. K. Pedlar, S. Pordes, E. Robutti, W. Roethel, J. L. Rosen, P. Rumerio, R. Rusack, A. Santroni, J. Schultz, S. H. Seo, K. K. Seth, G. Stancari, M. Stancari, A. Tomaradze, I. Uman, T. Vidnovic, S. Werkema, P. Zweber

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89 Scopus citations


We report evidence for the hc state of charmonium in its ηcγ decay mode and lack of evidence in the J/ψπ0 mode. We studied these channels in p̄p annihilations near the center of gravity of the PJ3 states, where the hc was reported in the J/ψπ0 mode by E760, our previous experiment, at 3526.2±0.15±0.2MeV, with ΓR≤1MeV. We observe an event excess in the ηcγ mode near 3526 MeV. Testing the null hypothesis of a linearly varying background cross section against the alternate hypothesis that includes a resonance near 3526 MeV, we reject the null hypothesis with P∼0.001. The resonance mass is 3525.8±0.2±0. 2MeV and the resonance width ≤1MeV. We estimate 10.0±3. 5<Γp̄pBηcγ<12.0±4.5eV, corresponding to fixed values 0.5<ΓR<1.0MeV. We find no event excess within the search region in the J/ψπ0 mode.

Original languageEnglish (US)
Article number032001
Pages (from-to)1-11
Number of pages11
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number3
StatePublished - Aug 1 2005


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