The decays $\chi_{ cJ}\to\gamma V$ ($V=\phi, \rho^0, \omega$) are studied with a sample of radiative $\psip\to\gamma\chi_{ cJ}$ events in a sample of $(1.06\pm0.04)\times 10^{ 8} \psip$ events collected with the BESIII detector. The branching fractions are determined to be: ${ \cal B}(\chi_{ c1}\to \gamma\phi)=(25.8\pm 5.2\pm 2.3)\times 10^{ -6}$, ${ \cal B}(\chi_{ c1}\to \gamma\rho^0)=(228\pm 13\pm 22)\times 10^{ -6}$, and ${ \cal B}(\chi_{ c1}\to \gamma\omega)=(69.7\pm 7.2\pm 6.6)\times 10^{ -6}$. The decay $\chi_{ c1}\to \gamma\phi$ is observed for the first time. Upper limits at the 90% confidence level on the branching fractions for $\chi_{ c0}$ and $\chict$ decays into these final states are determined. In addition, the fractions of the transverse polarization component of the vector meson in $\chi_{ c1}\to \gamma V$ decays are measured to be $0.29_{ -0.12-0.09}^{ +0.13+0.10}$ for $\chi_{ c1}\to \gamma\phi$, $0.158\pm 0.034^{ +0.015}_{ -0.014}$ for $\chi_{ c1}\to \gamma\rho^0$, and $0.247_{ -0.087-0.026}^{ +0.090+0.044}$ for $\chi_{ c1}\to \gamma\omega$, respectively. The first errors are statistical and the second ones are systematic.
Categories: hep-ex