Double Logarithms in $e^{+}{e}^{-}\to J/\psi +{\eta }_c$

Abstract

Double logarithms of $Q^2/m_c^2$ that appear in the cross section for $e^{+}{e}^{-}\to J/\psi +{\eta }_c$ at next-to-leading order (NLO) in the strong coupling ${\alpha }_s$ account for the bulk of the NLO correction at $B$-factory energies. (Here, $Q^2$ is the square of the center-of-momentum energy, and $m_c$ is the charm-quark mass.) We analyze the double logarithms that appear in the contribution of each NLO Feynman diagram, and we find that the double logarithms arise from both the Sudakov and the end-point regions of the loop integration. The Sudakov double logarithms cancel in the sum over all diagrams. We show that the end-point region of integration can be interpreted as a pinch-singular region in which a spectator fermion line becomes soft or soft and collinear to a produced meson. This interpretation may be important in establishing factorization theorems for helicity-flip processes, such as $e^{+}{e}^{-}\to J/\psi +{\eta }_c$, and in resumming logarithms of $Q^2/m_c^2$ to all orders in ${\alpha }_s$.

31 pages, 4 figures, 1 table, minor revisions, version published in PRD

References in corpus (7)

• QCD corrections to J/psi plus eta_c production in e+e- annihilation at sqrt{s}=10.6 GeV
• Resummation of Relativistic Corrections to e+ e- -> J/psi+eta_c
• Potential-model calculation of an order-v^2 NRQCD matrix element
• $O({\alpha }_s{v}^2)$ correction to $e^{+}{e}^{-}\to J/\psi +{\eta }_c$ at $B$ factories
• Refactorizing NRQCD short-distance coefficients in exclusive quarkonium production
• Factorization in exclusive quarkonium production
• Factorization theorems for exclusive heavy-quarkonium production