Measurement of chi(c1) (3872) production in proton-proton collisions at root s=8 and 13 TeV

The production cross-section of the χc1(3872) state relative to the ψ(2S) me- son is measured using proton-proton collision data collected with the LHCb experiment at centre-of-mass energies of √s = 8 and 13TeV, corresponding to integrated luminosi- ties of 2.0 and 5.4fb−1, respectively. The two mesons are reconstructed in the J/ψπ+π− final state. The ratios of the prompt and nonprompt χc1(3872) to ψ(2S) production cross- sections are measured as a function of transverse momentum, pT, and rapidity, y, of the χc1(3872) and ψ(2S) states, in the kinematic range 4 < pT < 20GeV/c and 2.0 < y < 4.5. The prompt ratio is found to increase with pT, independently of y. For the prompt compo- nent, the double ratio of the χc1(3872) and ψ(2S) production cross-sections between 13 and 8 TeV is observed to be consistent with unity, independent of pT and centre-of-mass energy.