Production of Prompt Charmonia in $e^+e^-$ Annihilation at $\sqrt{s}\approx 10.6$ GeV

Abstract

The production of prompt $J/ψ$, $ψ(2S)$, $χ_{c1}$ and $χ_{c2}$ is studied using a $32.4 fb^{-1}$ data sample collected with the Belle detector at the $Υ(4S)$ and 60 MeV below the resonance. The yield of prompt $J/ψ$ mesons in the $Υ(4S)$ sample is compatible with that of continuum production; we set an upper limit ${\cal B}(Υ(4S) \to J/ψX) < 1.9 \times 10^{-4}$ at the 95% confidence level, and find $σ(e^{+}e^{-} \to J/ψX)=1.47\pm 0.10 \pm 0.13$ pb. The cross-sections for prompt $ψ(2S)$ and direct $J/ψ$ are measured. The $J/ψ$ momentum spectrum, production angle distribution and polarization are studied.