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High Energy Physics - Experiment, hep-ex
MPINP:
LHCb - Abteilung Hofmann
Abstract:
Evidence for the decay mode $X(3872)\rightarrow\psi(2S)\gamma$ in
$B^+\rightarrow X(3872)K^+$ decays is found with a significance of 4.4 standard
deviations. The analysis is based on a data sample of proton-proton collisions,
corresponding to an integrated luminosity of 3fb$^{-1}$ collected with the LHCb
detector, at centre-of-mass energies of 7 and 8TeV. The ratio of the branching
fraction of the $X(3872)\to\psi(2S)\gamma$ decay to that of the
$X(3872)\rightarrow J/\psi \gamma$ decay is measured to be $$
\frac{Br(X(3872)\rightarrow\psi(2S)\gamma)}{Br(X(3872)\rightarrow
J/\psi\gamma)} = 2.46\pm0.64\pm0.29, %\pm0.06,$$ where the first uncertainty is
statistical and the second is systematic. The measured value agrees with
expectations for a pure charmonium interpretation of the $X(3872)$ state and a
mixture of charmonium and molecular interpretations. However, it does not
support a pure $D\bar{D}^{*}$ molecular interpretation of the $X(3872)$state.