The decays are studied using a
data set corresponding to an integrated luminosity of 9fb, collected
with the LHCb detector in proton-proton collisions at centre-of-mass energies
of 7, 8 and 13TeV. The decays and , where the
pair does not originate from a meson, are observed for the
first time. Precise measurements of the ratios of branching fractions between
intermediate , ,
and states are reported. A structure,
denoted as , is observed in the mass spectrum and,
assuming a Breit-Wigner parameterisation, its mass and width are determined to
be \begin{eqnarray*} m_{X(4740)} & = & 4741 \pm 6 \pm 6,{\mathrm{MeV}}/c^2 ,,
\ \Gamma_{X(4740)} & = & 53 \pm 15 \pm 11,{\mathrm{MeV}} ,, \end{eqnarray*}
where the first uncertainty is statistical and the second is systematic. In
addition, the most precise single measurement of the mass of the meson
is performed and gives a value of
Description
Keywords
B physics, Branching fraction, Hadron-Hadron scattering (experiments), Quarkonium, Spectroscopy