Higher-order multipole amplitudes in charmonium radiative transitions

M. Artuso, S. Blusk, S. Khalil, R. Mountain, K. Randrianarivony, T. Skwarnicki, S. Stone, J. C. Wang, L. M. Zhang, G. Bonvicini, D. Cinabro, A. Lincoln, M. J. Smith, P. Zhou, J. Zhu, P. Naik, J. Rademacker, D. M. Asner, K. W. Edwards, J. ReedA. N. Robichaud, G. Tatishvili, E. J. White, R. A. Briere, H. Vogel, P. U.E. Onyisi, J. L. Rosner, J. P. Alexander, D. G. Cassel, R. Ehrlich, L. Fields, R. S. Galik, L. Gibbons, S. W. Gray, D. L. Hartill, B. K. Heltsley, J. M. Hunt, D. L. Kreinick, V. E. Kuznetsov, J. Ledoux, H. Mahlke-Krüger, J. R. Patterson, D. Peterson, D. Riley, A. Ryd, A. J. Sadoff, X. Shi, S. Stroiney, W. M. Sun, J. Yelton, P. Rubin, N. Lowrey, S. Mehrabyan, M. Selen, J. Wiss, M. Kornicer, R. E. Mitchell, M. R. Shepherd, C. M. Tarbert, D. Besson, T. K. Pedlar, J. Xavier, D. Cronin-Hennessy, K. Y. Gao, J. Hietala, R. Poling, P. Zweber, S. Dobbs, Z. Metreveli, K. K. Seth, B. J.Y. Tan, A. Tomaradze, S. Brisbane, J. Libby, L. Martin, A. Powell, P. Spradlin, C. Thomas, G. Wilkinson, H. Mendez, J. Y. Ge, D. H. Miller, I. P.J. Shipsey, B. Xin, G. S. Adams, D. Hu, B. Moziak, J. Napolitano, K. M. Ecklund, J. Insler, H. Muramatsu, C. S. Park, E. H. Thorndike, F. Yang

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Abstract

Using 24×106 ψ′≡ψ(2S) decays in CLEO-c, we have searched for higher multipole admixtures in electric-dipole-dominated radiative transitions in charmonia. We find good agreement between our data and theoretical predictions for magnetic quadrupole (M2) amplitudes in the transitions ψ′→γχc1,c2 and χc1,c2→γJ/ ψ, in striking contrast to some previous measurements. Let b2J and a2J denote the normalized M2 amplitudes in the respective aforementioned decays, where the superscript J refers to the angular momentum of the χcJ. By performing unbinned maximum likelihood fits to full five-parameter angular distributions, we found the following values of M2 admixtures for Jχ=1: a2J=1=(-6.26±0.63±0.24)×10-2 and b2J=1=(2.76±0. 73±0.23)×10-2, which agree well with theoretical expectations for a vanishing anomalous magnetic moment of the charm quark. For Jχ=2, if we fix the electric octupole (E3) amplitudes to zero as theory predicts for transitions between charmonium S states and P states, we find a2J=2=(-9.3±1.6±0.3)×10-2 and b2J=2=(1.0±1. 3±0.3)×10-2. If we allow for E3 amplitudes we find, with a four-parameter fit, a2J=2=(-7.9±1.9±0.3)×10-2, b2J=2=(0.2±1.4±0.4)×10-2, a3J=2=(1.7±1.4±0.3) ×10-2, and b3J=2=(-0.8±1.2±0.2)×10-2. We determine the ratios a2J=1/a2J=2=0.67-0.13+0.19 and a2J=1/b2J=1=-2.27-0.99+0.57, where the theoretical predictions are independent of the charmed quark magnetic moment and are a2J=1/a2J=2=0.676±0.071 and a2J=1/b2J=1=-2.27±0.16.

Original languageEnglish (US)
Article number112003
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume80
Issue number11
DOIs
StatePublished - Dec 28 2009

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ASJC Scopus subject areas

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

Cite this

Artuso, M., Blusk, S., Khalil, S., Mountain, R., Randrianarivony, K., Skwarnicki, T., Stone, S., Wang, J. C., Zhang, L. M., Bonvicini, G., Cinabro, D., Lincoln, A., Smith, M. J., Zhou, P., Zhu, J., Naik, P., Rademacker, J., Asner, D. M., Edwards, K. W., ... Yang, F. (2009). Higher-order multipole amplitudes in charmonium radiative transitions. Physical Review D - Particles, Fields, Gravitation and Cosmology, 80(11), [112003]. https://doi.org/10.1103/PhysRevD.80.112003