Near-threshold $Dbar{D}$ spectroscopy and observation of a new charmonium state

Using proton-proton collision data, corresponding to an integrated luminosity of 9$fb^{-1}$, collected with the~LHCb detector between 2011 and 2018, a new narrow charmonium state, the $X(3842)$ resonance, is observed in the decay modes $X(3842)rightarrow D^0bar{D}^0$ and $X(3842)rightarrow D^+D^-$. The mass and the natural width of this state are measured to be begin{eqnarray*} m_{X(3842)} & = & 3842.71 pm 0.16 pm 0.12 MeV/c^2,, Gamma_{X(3842)} & = & 2.79 pm 0.51 pm 0.35 MeV,, end{eqnarray*} where the first uncertainty is statistical and the~second is systematic. The observed mass and narrow natural width suggest the~interpretation of the new state as the~unobserved spin obreakdash-3 $psi_3mathrm{left(1^3D_3right)}$ charmonium state. In addition, prompt hadroproduction of the $psi(3770)$~and $chi_{c2}(3930)$ states is observed for the first time, and the parameters of these~states are measured to be begin{eqnarray*} m_{psi(3770)} & = & 3778.1 pm 0.7 pm 0.6 MeV/c^2,, m_{chi_{c2}(3930)} & = & 3921.9 pm 0.6 pm 0.2 MeV/c^2,, Gamma_{chi_{c2}(3930)} & = &36.6 pm 1.9 pm 0.9 MeV,, end{eqnarray*} where the first uncertainty is statistical and the~second is systematic.