Observation of the P11 state of charmonium

P. Rubin*, C. Cawlfield, B. I. Eisenstein, G. D. Gollin, I. Karliner, D. Kim, N. Lowrey, P. Naik, C. Sedlack, M. Selen, E. J. White, J. Williams, J. Wiss, K. W. Edwards, D. Besson, T. K. Pedlar, D. Cronin-Hennessy, K. Y. Gao, D. T. Gong, J. HietalaY. Kubota, T. Klein, B. W. Lang, S. Z. Li, R. Poling, A. W. Scott, A. Smith, S. Dobbs, Z. Metreveli, K. K. Seth, A. Tomaradze, P. Zweber, J. Ernst, A. H. Mahmood, H. Severini, D. M. Asner, S. A. Dytman, W. Love, S. Mehrabyan, J. A. Mueller, V. Savinov, Z. Li, A. Lopez, H. Mendez, J. Ramirez, G. S. Huang, D. H. Miller, V. Pavlunin, B. Sanghi, I. P.J. Shipsey, G. S. Adams, M. Cravey, J. P. Cummings, I. Danko, J. Napolitano, Q. He, H. Muramatsu, C. S. Park, W. Park, E. H. Thorndike, T. E. Coan, Y. S. Gao, F. Liu, M. Artuso, C. Boulahouache, S. Blusk, J. Butt, O. Dorjkhaidav, J. Li, N. Menaa, R. Mountain, R. Nandakumar, K. Randrianarivony, R. Redjimi, R. Sia, T. Skwarnicki, S. Stone, J. C. Wang, K. Zhang, S. E. Csorna, G. Bonvicini, D. Cinabro, M. Dubrovin, R. A. Briere, G. P. Chen, J. Chen, T. Ferguson, G. Tatishvili, H. Vogel, M. E. Watkins, J. L. Rosner, N. E. Adam, J. P. Alexander, K. Berkelman, D. G. Cassel, V. Crede, J. E. Duboscq, K. M. Ecklund, R. Ehrlich, L. Fields, R. S. Galik, L. Gibbons, B. Gittelman, R. Gray, S. W. Gray, D. L. Hartill, B. K. Heltsley, D. Hertz, C. D. Jones, J. Kandaswamy, D. L. Kreinick, V. E. Kuznetsov, H. Mahlke-Krüger, T. O. Meyer, P. U.E. Onyisi, J. R. Patterson, D. Peterson, E. A. Phillips, J. Pivarski, D. Riley, A. Ryd, A. J. Sadoff, H. Schwarthoff, X. Shi, M. R. Shepherd, S. Stroiney, W. M. Sun, D. Urner, T. Wilksen, K. M. Weaver, M. Weinberger, S. B. Athar, P. Avery, L. Breva-Newell, R. Patel, V. Potlia, H. Stoeck, J. Yelton

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

118 Scopus citations


The spin-singlet P-wave state of charmonium, hc(1P1), has been observed in the decay ψ(2S)→π0hc followed by hc→γηc. Inclusive and exclusive analyses of the M(hc) spectrum have been performed. Two complementary inclusive analyses select either a range of energies for the photon emitted in hc→γηc or a range of values of M(ηc). These analyses, consistent with one another within statistics, yield M(hc)=[3524.9±0.7(stat)±0.4(sys)]MeV/c2 and a product of the branching ratios Bψ(ψ(2S)→π0hc)×Bh(hc→γηc)= [3.5±1.0(stat)±0.7(sys)]×10-4. When the ηc is reconstructed in seven exclusive decay modes, 17.5±4.5 hc events are seen with an average mass M(hc)=[3523.6±0.9(stat)±0.5(sys)]MeV/c2, and BψBh=[5.3±1.5(stat)±1.0(sys)]×10-4. If combined, the inclusive and exclusive data samples yield an overall mass M(hc)=[3524. 4±0.6(stat)±0.4(sys)]MeV/c2 and product of branching ratios BψBh=[4.0±0.8(stat)±0.7(sys)]×10-4. The hc mass implies a P-wave hyperfine splitting ΔMHF(1P)M(13P)-M(11P1)=[1.0±0.6(stat) ±0.4(sys)]MeV/c2.

Original languageEnglish (US)
Article number092004
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number9
StatePublished - Nov 1 2005

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


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