Phys. Rev. D
78,
091501(R)
(2008)
[6 pages]
Two-photon widths of the χcJ states of charmonium
K. M. Ecklund et al. CLEO Collaboration
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K. M. Ecklund1, W. Love2, V. Savinov2, A. Lopez3, H. Mendez3, J. Ramirez3, J. Y. Ge4, D. H. Miller4, I. P. J. Shipsey4, B. Xin4, G. S. Adams5, M. Anderson5, J. P. Cummings5, I. Danko5, D. Hu5, B. Moziak5, J. Napolitano5, Q. He6, J. Insler6, H. Muramatsu6, C. S. Park6, E. H. Thorndike6, F. Yang6, M. Artuso7, S. Blusk7, S. Khalil7, J. Li7, R. Mountain7, S. Nisar7, K. Randrianarivony7, N. Sultana7, T. Skwarnicki7, S. Stone7, J. C. Wang7, L. M. Zhang7, G. Bonvicini8, D. Cinabro8, M. Dubrovin8, A. Lincoln8, P. Naik9, J. Rademacker9, D. M. Asner10, K. W. Edwards10, J. Reed10, R. A. Briere11, T. Ferguson11, G. Tatishvili11, H. Vogel11, M. E. Watkins11, J. L. Rosner12, J. P. Alexander13, D. G. Cassel13, J. E. Duboscq13, R. Ehrlich13, L. Fields13, R. S. Galik13, L. Gibbons13, R. Gray13, S. W. Gray13, D. L. Hartill13, D. Hertz13, J. M. Hunt13, J. Kandaswamy13, D. L. Kreinick13, V. E. Kuznetsov13, J. Ledoux13, H. Mahlke-Krüger13, D. Mohapatra13, P. U. E. Onyisi13, J. R. Patterson13, D. Peterson13, D. Riley13, A. Ryd13, A. J. Sadoff13, X. Shi13, S. Stroiney13, W. M. Sun13, T. Wilksen13, S. B. Athar14, R. Patel14, J. Yelton14, P. Rubin15, B. I. Eisenstein16, I. Karliner16, S. Mehrabyan16, N. Lowrey16, M. Selen16, E. J. White16, J. Wiss16, R. E. Mitchell17, M. R. Shepherd17, D. Besson18, T. K. Pedlar19, D. Cronin-Hennessy20, K. Y. Gao20, J. Hietala20, Y. Kubota20, T. Klein20, B. W. Lang20, R. Poling20, A. W. Scott20, P. Zweber20, S. Dobbs21, Z. Metreveli21, K. K. Seth21, A. Tomaradze21, J. Libby22, A. Powell22, and G. Wilkinson22 (CLEO Collaboration)
1State University of New York at Buffalo, Buffalo, New York 14260, USA
2University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
3University of Puerto Rico, Mayaguez, Puerto Rico 00681
4Purdue University, West Lafayette, Indiana 47907, USA
5Rensselaer Polytechnic Institute, Troy, New York 12180, USA
6University of Rochester, Rochester, New York 14627, USA
7Syracuse University, Syracuse, New York 13244, USA
8Wayne State University, Detroit, Michigan 48202, USA
9University of Bristol, Bristol BS8 1TL, UK
10Carleton University, Ottawa, Ontario, Canada K1S 5B6
11Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
12Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637, USA
13Cornell University, Ithaca, New York 14853, USA
14University of Florida, Gainesville, Florida 32611, USA
15George Mason University, Fairfax, Virginia 22030, USA
16University of Illinois, Urbana-Champaign, Illinois 61801, USA
17Indiana University, Bloomington, Indiana 47405, USA
18University of Kansas, Lawrence, Kansas 66045, USA
19Luther College, Decorah, Iowa 52101, USA
20University of Minnesota, Minneapolis, Minnesota 55455, USA
21Northwestern University, Evanston, Illinois 60208, USA
22University of Oxford, Oxford OX1 3RH, UK
Received 19 March 2008; published 18 November 2008
Using a data sample of 24.5×106 ψ(2S) the reactions ψ(2S)→γχcJ, χcJ→γγ have been studied for the first time to determine the two-photon widths of the χcJ states of charmonium in their decay into two photons. The measured quantities are B(ψ(2S)→γχc0)×B(χc0→γγ)=(2.17±0.32±0.10)×10-5 and B(ψ(2S)→γχc2)×B(χc2→γγ)=(2.68±0.28±0.15)×10-5. Using values for B(ψ(2S)→γχc0,c2) and Γ(χc0,c2) from the literature the two-photon widths are derived to be Γγγ(χc0)=(2.36±0.35±0.22) keV, Γγγ(χc2)=(0.66±0.07±0.06) keV, and R≡Γγγ(χc2)/Γγγ(χc0)=0.278±0.050±0.036. The importance of the measurement of R is emphasized. For the forbidden transition, χc1→γγ, an upper limit of Γγγ(χc1)<0.03 keV is established.
© 2008 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevD.78.091501
DOI:
10.1103/PhysRevD.78.091501
PACS:
13.20.Gd, 13.40.Hq, 14.40.Gx
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