Study of the reactionψ′→γγJψ

Abstract

The Crystal Ball detector at SPEAR has been used to investigate the decays ${\psi }^{\prime }\to \gamma \gamma \frac{J}{\psi }$, $\frac{J}{\psi }\to (e^{+}{e}^{-} or {\mu }^{+}{\mu }^{-})$ resulting from production of $8\times {10}^5{\psi }^{\prime }$. From this selection of the data we measure the branching ratios for the processes ${\psi }^{\prime }\to (\eta or {\pi }^0)\frac{J}{\psi }$ and ${\psi }^{\prime }\to \gamma \chi$, $\chi \to \gamma \frac{J}{\psi }$. An analysis of the angular correlations in the latter process furnishes measurements of the $\chi \mathrm{}\left(3.55\right)\mathrm{}$ and $\chi \mathrm{}\left(3.51\right)\mathrm{}$ spins and of the multipole structure of the radiative transitions.