The decays B+ → J/ψ π+ π− K+ are studied using a data set corresponding to an integrated luminosity of 9 fb^−1 collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate ψ2(3823), χc1(3872) and ψ(2S) states are reported. The values are (B{B+ → ψ2(3823) K+} × B{ψ2(3823) → J/ψ π+ π−})/(B{B+ → χc1(3872) K+} × B{χc1(3872) → J/ψ π+ π−}) = (3.56 ± 0.67 ± 0.11) × 10^−2, (B{B+ → ψ2(3823) K+} × B{ψ2(3823) → J/ψ π+ π−})/(B{B+ → ψ(2S) K+} × B{ψ(2S) → J/ψ π+ π−}) = (1.31 ± 0.25 ± 0.04) × 10^−3, (B{B+ → χc1(3872) K+} × B{χc1(3872) → J/ψ π+ π−})/(B{B+ → ψ(2S) K+} × B{ψ(2S) → J/ψ π+ π−}) = (3.69 ± 0.07 ± 0.06) × 10^−2, where the first uncertainty is statistical and the second is systematic. The decay of B+ → ψ2(3823) K+ with ψ2(3823) → J/ψ π+ π− is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the ψ2(3823), χc1(3872) and ψ(2S) states are measured to be m{χc1(3872)} − m{ψ2(3823)} = 47.50 ± 0.53 ± 0.13 MeV/c^22, m{ψ2(3823)} − m{ψ(2S)} = 137.98 ± 0.53 ± 0.14 MeV/c^2, m{χc1(3872)} − m{ψ(2S)} = 185.49 ± 0.06 ± 0.03 MeV/c^2, resulting in the most precise determination of the χc1(3872) mass. The width of the ψ2(3823) state is found to be below 5.2 MeV at 90% confidence level. The Breit-Wigner width of the χc1(3872) state is measured to be Γ{χc1(3872)}^BW = 0.96{−0.18}{+0.19} ± 0.21 MeV which is inconsistent with zero by 5.5 standard deviations.

Aaij, R., Abellán Beteta, C., Ackernley, T., Adeva, B., Adinolfi, M., Afsharnia, H., et al. (2020). Study of the ψ2(3823) and χc1(3872) States in B+ → (J/ψ π+ π−) K+ Decays. JOURNAL OF HIGH ENERGY PHYSICS, 2020(8), 0-27 [10.1007/JHEP08(2020)123].

Study of the ψ2(3823) and χc1(3872) States in B+ → (J/ψ π+ π−) K+ Decays

Betti, F.;Capriotti, L.;Carbone, A.;Ferrari, F.;Galli, D.;Maccolini, S.;Manuzzi, D.;Patrignani, C.;Perazzini, S.;Pisani, F.;Zucchelli, S.;
2020

Abstract

The decays B+ → J/ψ π+ π− K+ are studied using a data set corresponding to an integrated luminosity of 9 fb^−1 collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate ψ2(3823), χc1(3872) and ψ(2S) states are reported. The values are (B{B+ → ψ2(3823) K+} × B{ψ2(3823) → J/ψ π+ π−})/(B{B+ → χc1(3872) K+} × B{χc1(3872) → J/ψ π+ π−}) = (3.56 ± 0.67 ± 0.11) × 10^−2, (B{B+ → ψ2(3823) K+} × B{ψ2(3823) → J/ψ π+ π−})/(B{B+ → ψ(2S) K+} × B{ψ(2S) → J/ψ π+ π−}) = (1.31 ± 0.25 ± 0.04) × 10^−3, (B{B+ → χc1(3872) K+} × B{χc1(3872) → J/ψ π+ π−})/(B{B+ → ψ(2S) K+} × B{ψ(2S) → J/ψ π+ π−}) = (3.69 ± 0.07 ± 0.06) × 10^−2, where the first uncertainty is statistical and the second is systematic. The decay of B+ → ψ2(3823) K+ with ψ2(3823) → J/ψ π+ π− is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the ψ2(3823), χc1(3872) and ψ(2S) states are measured to be m{χc1(3872)} − m{ψ2(3823)} = 47.50 ± 0.53 ± 0.13 MeV/c^22, m{ψ2(3823)} − m{ψ(2S)} = 137.98 ± 0.53 ± 0.14 MeV/c^2, m{χc1(3872)} − m{ψ(2S)} = 185.49 ± 0.06 ± 0.03 MeV/c^2, resulting in the most precise determination of the χc1(3872) mass. The width of the ψ2(3823) state is found to be below 5.2 MeV at 90% confidence level. The Breit-Wigner width of the χc1(3872) state is measured to be Γ{χc1(3872)}^BW = 0.96{−0.18}{+0.19} ± 0.21 MeV which is inconsistent with zero by 5.5 standard deviations.
2020
Aaij, R., Abellán Beteta, C., Ackernley, T., Adeva, B., Adinolfi, M., Afsharnia, H., et al. (2020). Study of the ψ2(3823) and χc1(3872) States in B+ → (J/ψ π+ π−) K+ Decays. JOURNAL OF HIGH ENERGY PHYSICS, 2020(8), 0-27 [10.1007/JHEP08(2020)123].
Aaij, R.; Abellán Beteta, C.; Ackernley, T.; Adeva, B.; Adinolfi, M.; Afsharnia, H.; Aidala, C.A.; Aiola, S.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; A...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/772400
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