| Abstract: | The decays $B^0_s
ightarrow J/psi pi^+pi^- K^+ K^-$ are studied using a
data set corresponding to an integrated luminosity of 9fb$^{-1}$, collected
with the LHCb detector in proton-proton collisions at centre-of-mass energies
of 7, 8 and 13TeV. The decays $B^0_s
ightarrow J/psi K^{ast0}
ar{K}^{ast0}$ and $B^0_s
ightarrow chi_{c1}(3872)K^+K^-$, where the
$K^+K^-$ pair does not originate from a $phi$ meson, are observed for the
first time. Precise measurements of the ratios of branching fractions between
intermediate $chi_{c1}(3872)phi$, $J/psi K^{ast0}ar{K}^{ast0}$,
$psi(2S)phi$ and $chi_{c1}(3872)K^+K^-$ states are reported. A structure,
denoted as $X(4740)$, is observed in the $J/psiphi$ mass spectrum and,
assuming a Breit-Wigner parameterisation, its mass and width are determined to
be egin{eqnarray*} m_{X(4740)} & = & 4741 pm 6 pm 6 MeV/c^2 ,, \
Gamma_{X(4740)} & = & 53 pm 15 pm 11 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 $B^0_s$ meson is performed and
gives a value of
$$ m_{B^0_s} = 5366.98 pm 0.07 pm 0.13 MeV/c^2,. $$ |
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