Comprehensive Calculations on the OZI-forbidden Nonleptonic Decays of Orthoquarkonia $J/\psi ({\rm Y})\to \pi \pi ,\rho \pi$

Abstract

In this work, we calculate the decay rates of the OZI-forbidden processes $J/\psi ({\rm Y})\to \pi \pi ,\rho \pi$ at the order of the leading-twist distribution amplitude. The process of $J/\psi ({\rm Y})\to {\pi }^{+}{\pi }^{-}$ violates isospin conservation and the amplitude is explicitly proportional to the isospin violation factor $m_u-m_d$, our numerical results on their decay rates are consistent with the data. The process $J/\psi ({\rm Y})\to \rho \pi$ violates the hadronic helicity conservation and should be suppressed, as indicated in literature, its decay rate can only be proportional to $m_q^2$ at the order of leading twist. Our theoretical evaluation confirms this statement that the theoretical evaluation on $\Gamma (J/\psi ({\rm Y})\to \rho \pi )$ is almost one order smaller than the data unless the model parameters take certain extreme values. It may imply that the sizable branching ratio of $J/\psi ({\rm Y})\to \rho \pi$ should be explained by either higher twist contributions or other mechanisms.

25 pages, 1 figure and 4 tables. Numerical results slightly changed

References in corpus (1)

• Study of electromagnetic decay of $J/\psi$ and ${\psi }^{\prime }$ to vector and pseudoscalar