Measurement of the relative rate of prompt $\ddot{I}{‡}_{c0}$, $\ddot{I}{‡}_{c1}$ and $\ddot{I}{‡}_{c2}$ production at $\sqrt{s}=7$TeV

Abstract

Prompt production of charmonium $\ddot{I}{‡}_{c0}$, $\ddot{I}{‡}_{c1}$ and $\ddot{I}{‡}_{c2}$ mesons is studied using proton-proton collisions at the LHC at a centre-of-mass energy of $\sqrt{s}=7$TeV. The $\ddot{I}{‡}_c$ mesons are identified through their decay to $J/\ddot{I}ˆ{\hat{I}}^3$, with $J/\ddot{I}ˆ\to \hat{I}{¼}^{+}\hat{I}{¼}^{-}$ using photons that converted in the detector. A data sample, corresponding to an integrated luminosity of $1.0{\mathrm{fb}}^{-1}$ collected by the LHCb detector, is used to measure the relative prompt production rate of $\ddot{I}{‡}_{c1}$ and $\ddot{I}{‡}_{c2}$ in the rapidity range $2.0<y<4.5$ as a function of the $J/\ddot{I}ˆ$ transverse momentum from 3 to 20 GeV$/c$. First evidence for $\ddot{I}{‡}_{c0}$ meson production at a high-energy hadron collider is also presented.