Production of Prompt Charmonia in e+e− Annihilation at s≈10.6GeV

Le résumé fourni par la source

The production of prompt $J/\ensuremath{\psi}$, $\ensuremath{\psi}(2S)$, ${\ensuremath{\chi}}_{c1}$, and ${\ensuremath{\chi}}_{c2}$ is studied using a $32.4{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected with the Belle detector at $\ensuremath{\Upsilon}(4S)$ and at $60\mathrm{MeV}$ below the resonance. The yield of prompt $J/\ensuremath{\psi}$ mesons in the $\ensuremath{\Upsilon}(4S)$ sample is compatible with that of continuum production; we set an upper limit $B(\ensuremath{\Upsilon}(4S)\ensuremath{\rightarrow}J/\ensuremath{\psi}X)<1.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ at the $95%$ confidence level, and find $\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}X)\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.47\ifmmode\pm\else\textpm\fi{}0.10\ifmmode\pm\else\textpm\fi{}0.13\mathrm{pb}$. The cross sections for prompt $\ensuremath{\psi}(2S)$ and direct $J/\ensuremath{\psi}$ are measured. The $J/\ensuremath{\psi}$ momentum spectrum, production angle distribution, and polarization are studied.

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