Studies of and mesons including the observation of the decay in proton-proton collisions at .

Measurements of and mesons are performed using a data sample of proton-proton collisions corresponding to an integrated luminosity of , collected with the CMS detector at the LHC at a centre-of-mass energy of . The analysis studies -wave meson decays into and , where the and mesons are identified using the decays and . The masses of the -wave meson states are measured and the natural width of the state is determined. The first measurement of the mass difference between the charged and neutral mesons is also presented. The decay to is observed, together with a measurement of its branching fraction relative to the decay.