Formation of the ${\eta }_c$ in Two-Photon Collisions at LEP

Abstract

The two-photon width ${\Gamma }_{\gamma \gamma }$ of the ${\eta }_c$ meson has been measured with the L3 detector at LEP. The ${\eta }_c$ is studied in the decay modes ${\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$, ${\pi }^{+}{\pi }^{-}$K${}^{+}$K${}^{-}$, K${}_s^0$K${}^{\pm }{\pi }^{\mp }$, K${}^{+}$K${}^{-}{\pi }^0$, ${\pi }^{+}{\pi }^{-}\eta$, ${\pi }^{+}{\pi }^{-}{\eta }^{\prime }$, and ${\rho }^{+}{\rho }^{-}$ using an integrated luminosity of 140 pb${}^{-1}$ at $\sqrt{s}\simeq 91$ GeV and of 52 pb${}^{-1}$ at $\sqrt{s}\simeq 183$ GeV. The result is ${\Gamma }_{\gamma \gamma }({\eta }_c)=6.9\pm 1.7(stat.)\pm 0.8(sys.)\pm 2.0$(BR) keV. The $Q^2$ dependence of the ${\eta }_c$ cross section is studied for $Q^2<9$ GeV${}^2$. It is found to be better described by a Vector Meson Dominance model form factor with a J-pole than with a $\rho$-pole. In addition, a signal of $29\pm 11$ events is observed at the ${\chi }_{c}0$ mass. Upper limits for the two-photon widths of the ${\chi }_{c}0$, ${\chi }_{c}2$, and ${\eta }_c^{\prime }$ are also given.

Cited by in corpus (14)

• Observation of the eta_c(2S) in exclusive B-->K KsK-pi+ decays
• Observation of eta_c^{prime} Production in gamma gamma Fusion at CLEO
• Measurements of the mass and width of the eta_c meson and of an eta_c(2S) candidate
• The two-gluon components of the eta and eta' mesons to leading-twist accuracy
• Two Photon Decays of Charmonia from Lattice QCD
• Measurement of the gamma gamma* --> eta_c transition form factor
• Annihilation Rate of Heavy $0^{-+}$ Quarkonium in Relativistic Salpeter Method
• Search for gammagamma -> eta_b in e+e- collisions at LEP2
• Study of charmonia in four-meson final states produced in two-photon collisions
• First-principle calculation of ${\eta }_c\to 2\gamma$ decay width from lattice QCD
• The eta_c(2980) formation in two-photon collisions at LEP energies
• Form factors of ${\eta }_c$ in light front quark model
• Search for Missing Charmonium States in B-meson Decays
• Finding eta_c' and h_c at HERA-B