O(αsv2)O(\alpha_s v^2) correction to e+e−→J/ψ+ηce^+e^-\to J/\psi+\eta_c at BB factories

We investigate the ${\mathcal O}(\alpha_s v^2)$ correction to the $e^+e^-\to J/\psi+\eta_c$ process in the nonrelativistic QCD (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 only mildly enhances the existing NRQCD predictions. 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 next-to-leading order in $\alpha_s$, the double logarithm of type $\ln^2 (s/m_c^2)$ appearing in various NRQCD short-distance coefficients is always associated with the helicity-suppressed channels.Comment: v3, 6 pages, 2 figures, 1 table; matching the published versio

Some recent progress in understanding exclusive double charmonium production at BB factories

We review some recent progress in understanding various exclusive double charmonium production processes at $B$ factories, within the nonrelativistic QCD factorization framework. First we investigate the impact of the joint perturbative and relativistic correction on the process that has attracted a great amount of attention in the past decade, $e^+e^-\to J/\psi+\eta_c$. We then briefly discuss the phenomenological implication of the next-to-leading order perturbative correction to the processes $e^+e^-\to J/\psi+\chi_{c0,1,2} (\eta_{c2})$. We further emphasize a novel theoretical challenge, which is recently discovered by applying the NRQCD factorization approach to the helicity-suppressed hard exclusive reactions involving heavy quarkonium.Comment: 9 pages, 2 figures, 1 table. Talk given by Y. J. at the Xth Quark Confinement and the Hadron Spectrum, 8-12 October 2012, TUM Campus Garching, Munich, German