Study of $\psi(2S)$ decays into $\gamma K^+K^-$ and $\gamma \pi^+\pi^-$

Abstract

Radiative charmonium decays from the BESII sample of 14$\times10^{6}$ $\psi(2S)$-events into two different final states, $\gamma K^+K^-$ and $\gamma\pi^+\pi^-$, are analyzed. Product branching fractions for $\psi(2S)\to\gamma X\to \gamma\pi^+\pi^-$, $\gamma K^+K^-$ are given, where $X=f_2(1270)$, $f_0(1500)$, and $f_0(1710)$ in $\pi^+\pi^-$ and $f_2(1270)$, $f_2'(1525)$, and $f_0(1700)$ in $K^+K^-$. An angular analysis gives the ratios of the helicity projections for the $f_2(1270)$ in $\psi(2S)\to\gamma f_2(1270)\to\gamma\pi^+\pi^-$.