The production cross-section of the χc1(3872) state relative to the
ψ(2S) meson is measured using proton-proton collision data collected with
the LHCb experiment at centre-of-mass energies of s=8 and 13 TeV,
corresponding to integrated luminosities of 2.0 and 5.4 fb−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, in the kinematic range 4<pT<20 GeV/c and 2.0<y<4.5. The prompt ratio is found to increase with
pT independently of y. The double-differential cross-section ratio
of χc1(3872) relative to ψ(2S) mesons between 13 and 8 TeV is also
measured for the prompt component and observed to be consistent with unity,
independent of pT and centre-of-mass energy