The evasion of helicity selection rule in ${\chi }_{c1}\to VV$ and ${\chi }_{c2}\to VP$ via intermediate charmed meson loops

The hadronic decays of ${\chi }_{c1}\to VV$ and ${\chi }_{c2}\to VP$ are supposed to be suppressed by the helicity selection rule in the pQCD framework. With an effective Lagrangian method, we show that the intermediate charmed meson loops can provide a mechanism for the evasion of the helicity selection rule, and result in sizeable decay branching ratios in some of those channels. The theoretical predictions can be examined by the forthcoming BES-III data in the near future.