Search for long-lived scalar particles in $B^+ \to K^+ \chi (\mu^+\mu^-)$ decays

Understand

A search for a long-lived scalar particle $\chi$ is performed, looking for the decay ${B^+ \to K^+ \chi}$ with ${\chi \to \mu^+\mu^-}$ in $pp$ collision data corresponding to an integrated luminosity of $3\, {\rm fb}^{-1}$, collected by the LHCb experiment at centre-of-mass energies of $\sqrt{s}=7$ and 8$\,$TeV.

• This new scalar particle, predicted by Hidden Sector models, is assumed to have a narrow width.
• The signal would manifest itself as an excess in the dimuon invariant mass distribution over the Standard Model background.
• No significant excess is observed in the accessible ranges of mass ${250 < m(\chi) < 4700\,\rm MeV/c^2}$ and lifetime ${0.1 < \tau(\chi) < 1000\,\rm ps}$.