Two-photon widths of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>χ</mml:mi><mml:mrow><mml:mi>c</mml:mi><mml:mi>J</mml:mi></mml:mrow></mml:msub></mml:math>states of charmonium
Two-photon widths of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>χ</mml:mi><mml:mrow><mml:mi>c</mml:mi><mml:mi>J</mml:mi></mml:mrow></mml:msub></mml:math>states of charmonium
Using a data sample of $24.5\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $\ensuremath{\psi}(2S)$ the reactions $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{cJ}$, ${\ensuremath{\chi}}_{cJ}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ have been studied for the first time to determine the two-photon widths of the ${\ensuremath{\chi}}_{cJ}$ states of charmonium in their decay into two photons. The measured quantities are $\mathcal{B}(\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c0})\ifmmode\times\else\texttimes\fi{}\mathcal{B}({\ensuremath{\chi}}_{c0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma})=(2.17\ifmmode\pm\else\textpm\fi{}0.32\ifmmode\pm\else\textpm\fi{}0.10)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ and $\mathcal{B}(\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c2})\ifmmode\times\else\texttimes\fi{}\mathcal{B}({\ensuremath{\chi}}_{c2}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma})=(2.68\ifmmode\pm\else\textpm\fi{}0.28\ifmmode\pm\else\textpm\fi{}0.15)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$. Using values for $\mathcal{B}(\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c0,c2})$ and $\ensuremath{\Gamma}({\ensuremath{\chi}}_{c0,c2})$ from the …