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Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/131790
Analysis of the resonant components in ¯¯¯B0→J/ψπ+π−
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Interpretation of C P violation measurements using charmonium decays, in both the ¯¯¯ B 0 and ¯¯¯ B 0 s systems, can be subject to changes due to "penguin" type diagrams. These effects can be investigated using measurements of the Cabibbo-suppressed ¯¯¯ B 0 → J / ψ π + π − decays. The final state composition of this channel is investigated using a 1.0 fb − 1 sample of data produced in 7 TeV p p collisions at the LHC and collected by the LHCb experiment. A modified Dalitz-plot analysis is performed using both the invariant mass spectra and the decay angular distributions. An improved measurement of the ¯¯¯ B 0 → J / ψ π + π − branching fraction of ( 3.97 ± 0.09 ± 0.11 ± 0.16 ) × 10 − 5 is reported where the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty of the branching fraction of the decay B − → J / ψ K − used as a normalization channel. Significant production of f 0 ( 500 ) and ρ ( 770 ) resonances is found in the substructure of the J / ψ π + π − final state, and this indicates that they are viable final states for C P violation studies. In contrast evidence for the f 0 ( 980 ) resonance is not found. This allows us to establish the first upper limit on the branching fraction product B ( ¯¯¯ B 0 → J / ψ f 0 ( 980 ) ) × B ( f 0 ( 980 ) → π + π − ) < 1.1 × 10 − 6 , leading to an upper limit on the absolute value of the mixing angle of the f 0 ( 980 ) with the f 0 ( 500 ) of less than 31°, both at 90% confidence level.
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ABELLAN BETETA, Carlos, CALVO GÓMEZ, Míriam, CAMBONI, Alessandro, COMERMA MONTELLS, Albert, DOMINGO BONAL, Francesc, GARRIDO BELTRÁN, Lluís, GRACIANI DÍAZ, Ricardo, GRAUGÉS POUS, Eugeni, LÓPEZ ASAMAR, Elias, PÉREZ-CALERO YZQUIERDO, Antonio, POTTERAT, Cédric, RIVES MOLINA, Vicente josé, RUIZ, Hugo (ruiz pérez), VÁZQUEZ GÓMEZ, Ricard, VILASIS-CARDONA, Xavier, LHCb Collaboration. Analysis of the resonant components in ¯¯¯B0→J/ψπ+π−. _Physical Review D_. 2013. Vol. 87, núm. 11, pàgs. 052001. [consulta: 26 de febrer de 2026]. ISSN: 1550-7998. [Disponible a: https://hdl.handle.net/2445/131790]