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Evidence for $X(3872)rightarrow J/psi pi^+pi^-$ produced in single-tag two-photon interactions

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 نشر من قبل Yoshiki Teramoto
 تاريخ النشر 2020
  مجال البحث
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We report the first evidence for $X(3872)$ production in two-photon interactions by tagging either the electron or the position in the final state, exploring the highly virtual photon region. The search is performed in $e^+e^- rightarrow e^+e^-J/psipi^+pi^-$, using 825 fb$^{-1}$ of data collected by the Belle detector operated at the KEKB $e^+e^-$ collider. We observe three $X(3872)$ candidates with an expected background of $0.11pm 0.10$ events, with a significance of 3.2$sigma$. We obtain an estimated value for $tilde{Gamma}_{gammagamma}{cal B}(X(3872)rightarrow J/psipi^+pi^-$) assuming the $Q^2$ dependence predicted by a $cbar{c}$ meson model, where $-Q^2$ is the invariant mass-squared of the virtual photon. No $X(3915)rightarrow J/psipi^+pi^-$ candidates are found.



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