Study of the χ1 and χ2 charmonium states formed in pp annihilations

T. A. Armstrong*, D. Bettoni, V. Bharadwaj, C. Biino, G. Borreani, D. R. Broemmelsiek, A. Buzzo, R. Calabrese, A. Ceccucci, R. Cester, M. D. Church, P. Dalpiaz, M. Dameri, D. Dimitroyannis, M. Fabbri, J. E. Fast, S. Ferroni, M. Gee, C. M. Ginsburg, K. E. GollwitzerA. A. Hahn, M. A. Hasan, S. Y. Hsueh, R. A. Lewis, E. Luppi, M. Macrí, A. M. Majewska, M. A. Mandelkern, F. Marchetto, M. Marinelli, J. L. Marques, W. Marsh, M. Martini, M. Masuzawa, E. Menichetti, A. Migliori, R. Mussa, S. Palestini, N. Pastrone, C. Patrignani, J. Peoples, L. Pesando, F. Petrucci, M. G. Pia, S. Pordes, P. A. Rapidis, R. E. Ray, J. D. Reid, G. Rinaudo, J. L. Rosen, A. Santroni, M. Sarmiento, M. Savrié, J. Schultz, K. K. Seth, G. A. Smith, L. Tecchio, S. Tommasini, S. Trokenheim, M. F. Weber, S. J. Werkema, Y. Zhang, J. L. Zhao, G. Zioulas, M. Zito

*Corresponding author for this work

Research output: Contribution to journalArticle

72 Scopus citations


We report on a study of the χ1(3P1) and χ2(3P2) states of charmonium formed in antiproton-proton annihilations. An energy scan through the resonances, performed with a very narrow momentum-band beam of antiprotons intersecting a hydrogen jet target, enables us to perform very precise measurements of the mass and the total width of the two resonances. From a sample of 513 χ1 and 585 χ2 events we find Mχ1 = (3510.53±0.13) MeV/c2, Mχ2 = (3556.15±0.14) MeV/c2, Γχ1 = (0.88±0.14) MeV and Γχ2 = (1.98±0.18) MeV. From our measurement of the quantity Γ(R → pp) × BR(R → J ψ → e+ e-), using known branching ratios, we obtain Λ(χ1 → pp) = (69±13) eV and Λ(χ2 → pp) = (180±31) eV.

Original languageEnglish (US)
Pages (from-to)35-54
Number of pages20
JournalNuclear Physics, Section B
Issue number1
StatePublished - Mar 30 1992

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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    Armstrong, T. A., Bettoni, D., Bharadwaj, V., Biino, C., Borreani, G., Broemmelsiek, D. R., Buzzo, A., Calabrese, R., Ceccucci, A., Cester, R., Church, M. D., Dalpiaz, P., Dameri, M., Dimitroyannis, D., Fabbri, M., Fast, J. E., Ferroni, S., Gee, M., Ginsburg, C. M., ... Zito, M. (1992). Study of the χ1 and χ2 charmonium states formed in pp annihilations. Nuclear Physics, Section B, 373(1), 35-54.