Abstract
The cross section values of $J/\psi\ \eta_c$ and $J/\psi\ J/\psi$ production in $e^+e^-$ annihilation are estimated within one-loop approximation near $Z$ pole, as well as at higher energies. Both intermediate bosons, $\gamma$ and $Z$, are taken into account. It is shown that at $Z$ mass the NLO contribution increases the cross-section values by 3.5 times.
Highlights
The associative production of J=ψ ηc in eþe− annihilation was studied experimentally in detail by Belle and BABAR Collaborations at the energy around 10.6 GeV [1,2]
The cross sections of J=ψ ηc and J=ψ J=ψ production in eþe− annihilation are calculated at a one-loop accuracy near Z-boson pole and at higher energies as well
The analytical expressions for leading order cross sections are quite simple, and we present them below, highlighting the contributions of the γà decay, the Zà decay and the interference between γà and Zà as per Eqs. (11)–(12), σJ=ψ ηc
Summary
The associative production of J=ψ ηc in eþe− annihilation was studied experimentally in detail by Belle and BABAR Collaborations at the energy around 10.6 GeV [1,2]. It turned out that the cross section value predicted within the leading-order (LO) approximation was by a factor of more than 5 smaller than the experimental measurement. This significant difference has initiated an intensive study of various corrections to the LO mechanism. Two sources of corrections were mainly considered. [3], which initiated the discussion on this contribution, and followed by Refs. There are results where both types of corrections were considered and applied [19,20]. Evaluating the theoretical results in this field, one tends to believe that both mechanisms are required to correctly describe the data
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