Alfonso Albero, AlejandroCalvo Gómez, MíriamCamboni, AlessandroCoquereau, SamuelGarcía Moreno, PaulaGarrido Beltrán, LluísGascón Fora, DavidGironella Gironell, PereGolobardes, ElisabetGraciani Díaz, RicardoGraugés Pous, EugeniManera Escalero, R.Vilasis-Cardona, XavierLHCb Collaboration2021-03-112021-03-112020-11-122470-0010https://hdl.handle.net/2445/174899A study of the lineshape of the χc1(3872) state is made using a data sample corresponding to an integrated luminosity of 3  fb−1 collected in pp collisions at center-of-mass energies of 7 and 8 TeV with the LHCb detector. Candidate χc1(3872) and ψ(2S) mesons from b-hadron decays are selected in the J/ψπ+π− decay mode. Describing the lineshape with a Breit-Wigner function, the mass splitting between the χc1(3872) and ψ(2S) states, Δm, and the width of the χc1(3872) state, ΓBW, are determined to be Δm=185.598±0.067±0.068  MeV,ΓBW=1.39±0.24±0.10  MeV, where the first uncertainty is statistical and the second systematic. Using a Flatté-inspired model, the mode and full width at half maximum of the lineshape are determined to be mode=3871.69+0.00+0.05−0.04−0.13  MeV,FWHM=0.22+0.07+0.11−0.06−0.13  MeV. An investigation of the analytic structure of the Flatté amplitude reveals a pole structure, which is compatible with a quasibound D0¯D*0 state but a quasivirtual state is still allowed at the level of 2 standard deviations.20 p.application/pdfengcc-by (c) Aaij, R. et al., 2020http://creativecommons.org/licenses/by/3.0/es/Gran Col·lisionador d'HadronsMesons (Física nuclear)BarionsLarge Hadron Collider (France and Switzerland)Mesons (Nuclear physics)Baryonsinfo:eu-repo/semantics/article7064762021-03-11info:eu-repo/semantics/openAccess