Abstract
Using data taken with the CLEO-c detector at the Cornell Electron Storage Ring, we have investigated the direct-photon momentum spectrum in the decay J/psi(1S)->gamma gg, via the "tagged" process: e(+)e(-)->psi(2S); psi(2S)-> J/psi pi(+)pi(-); J/psi ->gamma+X. Including contributions from two-body radiative decay processes, we find the ratio of the inclusive direct-photon branching fraction to that of the dominant three-gluon branching fraction [R-gamma=B(gg gamma)/B(ggg)] to be R-gamma=0.137 +/- 0.001 +/- 0.016 +/- 0.004, where the errors shown are statistical, systematic, and the model-dependent uncertainty related to the extrapolation to zero photon energy. The shape of the scaled photon energy spectrum in J/psi -> gg gamma is observed to be very similar to that of Upsilon -> gg gamma. The R-gamma value obtained is roughly consistent with that expected by a simple quark-charge scaling [R-gamma similar to(q(c)/q(b))(2)] of the value determined at the Upsilon(1S), but somewhat higher than the value expected from the running of the strong coupling constant.
Published in:
Physical Review D 78,3 ( 2008 )
Keywords
Astronomy & Astrophysics;; Physics, Particles & Fields
Date of Version
January 2008
Recommended Citation
Besson, D.; Pedlar, T. K.; Cronin-Hennessy, D.; Gao, K. Y.; Hietala, J.; Kubota, Y.; Klein, T.; Lang, B. W.; Poling, R.; Scott, A. W.; Zweber, P.; Dobbs, S.; Metreveli, Z.; Seth, K. K.; Tomaradze, A.; Libby, J.; Powell, A.; Wilkinson, G.; Ecklund, K. M.; Love, W.; Savinov, V.; Mendez, H.; Ge, J. Y.; Miller, D. H.; Shipsey, I. P. J.; Xin, B.; Adams, G. S.; Anderson, M.; Cummings, J. P.; Danko, I.; Hu, D.; Moziak, B.; Napolitano, J.; He, Q.; Insler, J.; Muramatsu, H.; Park, C. S.; Thorndike, E. H.; Yang, F.; Artuso, M.; Blusk, S.; Khalil, S.; Li, J.; Mountain, R.; Nisar, S.; Randrianarivony, K.; Sultana, N.; Skwarnicki, T.; Stone, S.; Wang, J. C.; Zhang, L. M.; Bonvicini, G.; Cinabro, D.; Dubrovin, M.; Lincoln, A.; Naik, P.; Rademacker, J.; Asner, D. M.; Edwards, K. W.; Reed, J.; Briere, R. A.; Ferguson, T.; Tatishvili, G.; Vogel, H.; Watkins, M. E.; Rosner, J. L.; Alexander, J. P.; Cassel, D. G.; Duboscq, J. E.; Ehrlich, R.; Fields, L.; Galik, R. S.; Gibbons, L.; Gray, R.; Gray, S. W.; Hartill, D. L.; Heltsley, B. K.; Hertz, D.; Hunt, J. M.; Kandaswamy, J.; Kreinick, D. L.; Kuznetsov, V. E.; Ledoux, J.; Mahlke-Kruger, H.; Mohapatra, D.; Onyisi, P. U. E.; Patterson, J. R.; Peterson, D.; Riley, D.; Ryd, A.; Sadoff, A. J.; Shi, X.; Stroiney, S.; Sun, W. M.; Wilksen, T.; Athar, S. B.; Patel, R.; Yelton, J.; Rubin, P.; Eisenstein, B. I.; Karliner, I.; Mehrabyan, S.; Lowrey, N.; Selen, M.; White, E. J.; Wiss, J.; Mitchell, R. E.; and Shepherd, M. R., "Inclusive radiative J/psi decays" (2008). Department of Physics and Astronomy Faculty Publications. Paper 917.
https://docs.lib.purdue.edu/physics_articles/917