1204.4128 (Hai-Rong Dong et al.)

$O(α_s v^2)$ correction to $e^+e^-\to J/ψ+η_c$ at $B$
factories    [PDF]

Hai-Rong Dong, Feng Feng, Yu Jia

We investigate the ${\mathcal O}(\alpha_s v^2)$ correction to the $e^+e^-\to J/\psi+\eta_c$ process in the NRQCD factorization approach. Within some reasonable choices of the relative order-$v^2$ NRQCD matrix elements, we find that including this new ingredient of correction helps very little to alleviate the discrepancy between the theory and the $B$ factory measurements. We have also deduced the asymptotic expressions for the ${\mathcal O}(\alpha_s v^2)$ short-distance coefficients, and reconfirm the early speculation that at NLO in $\alpha_s$, the double logarithm of type $\ln^2 (s/m_c^2)$ appearing in the NRQCD short-distance coefficient is always associated with the helicity-suppressed channels.

View original: http://arxiv.org/abs/1204.4128