Comerma Montells, AlbertGarcia Moreno, PaulaGarrido Beltrán, LluísGioventù, AlessandraGironella Gironell, PereGomez Fernandez, SergioGraugés Pous, EugeniLobo Salvia, AniolLópez Huertas, AlbertManera Escalero, RafelMarin Benito, CarlaMauricio Ferre, JoanAlfonso Albero, AlejandroVazquez Gomez, RicardoLHCb Collaboration2025-06-272025-06-2720241126-6708https://hdl.handle.net/2445/221838 The cross-section of associated J/ψ-ψ(2S) production in proton-proton collisions at a centre-of-mass energy of √ s = 13 TeV is measured using a data sample corresponding to an integrated luminosity of 4.2 fb−1 , collected by the LHCb experiment. The measurement is performed for both J/ψ and ψ(2S) mesons having transverse momentum pT < 14 GeV/c and rapidity 2.0 < y < 4.5, assuming negligible polarisation of the J/ψ and ψ(2S) mesons. The production cross-section is measured to be 4.5 ± 0.7 ± 0.3 nb, where the frst uncertainty is statistical and the second systematic. The diferential cross-sections are measured as functions of several kinematic variables of the J/ψ-ψ(2S) candidates. The results are combined with a measurement of J/ψ-J/ψ production, giving a cross-section ratio between J/ψ-ψ(2S) and J/ψ-J/ψ production of 0.274 ± 0.044 ± 0.008, where the frst uncertainty is statistical and the second systematic. 1 p.application/pdfengcc-by (c) Aaij, R. et al., 2024http://creativecommons.org/licenses/by/4.0/Cromodinàmica quànticaHadronsCol·lisions (Física)Quantum chromodynamicsHadronsCollisions (Physics)info:eu-repo/semantics/article7564542025-06-27info:eu-repo/semantics/openAccess