Experimental Investigation of the Two-Photon Widths of the ${\chi }_{c0}$ and the ${\chi }_{c2}$ Mesons

Abstract

Using 12.7 $f{b}^{-1}$ of data collected with the CLEO detector at CESR, we observed two-photon production of the $c\bar{c}$ states ${\chi }_{c0}$ and ${\chi }_{c2}$ in their decay to ${\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$. We measured ${\Gamma }_{\gamma \gamma }({\chi }_c)\times \mathcal{B}({\chi }_c\to {\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-})$ to be 75 +- 13 (stat) +- 8 (syst) eV for the ${\chi }_{c0}$ and 6.4 +- 1.8 (stat) +- 0.8 (syst) eV for the ${\chi }_{c2}$, implying ${\Gamma }_{\gamma \gamma }({\chi }_{c0})$ = 3.76 +- 0.65 (stat) +- 0.41 (syst) +- 1.69 (br) keV and ${\Gamma }_{\gamma \gamma }({\chi }_{c2})$ = 0.53 +- 0.15 (stat) +- 0.06 (syst) +- 0.22 (br) keV. Also, cancelation of dominant experimental and theoretical uncertainties permits a precise comparison of ${\Gamma }_{\gamma \gamma }({\chi }_{c0})/{\Gamma }_{\gamma \gamma }({\chi }_{c2})$, evaluated to be 7.4 +- 2.4 (stat) +- 0.5 (syst) +- 0.9 (br), with QCD-based predictions.

10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS