Near-threshold $D\bar{D}$ 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 $ \mathrm{X}(3842)\to {D}^0{\overline{D}}^0 $ and X(3842) → D$^{+}$D$^{−}$. The mass and the natural width of this state are measured to be