In:
Journal of High Energy Physics, Springer Science and Business Media LLC, Vol. 2019, No. 9 ( 2019-09)
Abstract:
Using proton-proton collision data, collected with the LHCb detector and corresponding to 1.0, 2.0 and 1.9 fb −1 of integrated luminosity at the centre-of-mass energies of 7, 8, and 13 TeV, respectively, the decay $$ {\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1} $$ Λ b 0 → χ c 1 (3872)pK − with χ c1 (3872) → J / ψ π + π − is observed for the first time. The significance of the observed signal is in excess of seven standard deviations. It is found that (58 ± 15)% of the decays proceed via the two-body intermediate state χ c1 (3872)Λ(1520). The branching fraction with respect to that of the $$ {\Lambda}_{\mathrm{b}}^0 $$ Λ b 0 → ψ(2S)pK − decay mode, where the ψ(2S) meson is reconstructed in the J / ψ π + π − final state, is measured to be: $$ \frac{\beta \left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1}(3872){\mathrm{pK}}^{-}\right)}{\beta \left({\Lambda}_{\mathrm{b}}^0\to \uppsi \left(2\mathrm{S}\right){\mathrm{pK}}^{-}\right)}\times \frac{\beta \left({\upchi}_{\mathrm{c}1}(3872)\to \mathrm{J}/\uppsi {\uppi}^{+}{\uppi}^{-}\right)}{\beta \left(\uppsi \left(2\mathrm{S}\right)\to \mathrm{J}/\uppsi {\uppi}^{+}{\uppi}^{-}\right)}=\left(5.4\pm 1.1\pm 0.2\right)\times {10}^{-2}, $$ β Λ b 0 → χ c 1 3872 pK − β Λ b 0 → ψ 2 S pK − × β χ c 1 3872 → J / ψ π + π − β ψ 2 S → J / ψ π + π − = 5.4 ± 1.1 ± 0.2 × 10 − 2 , where the first uncertainty is statistical and the second is systematic.
Type of Medium:
Online Resource
ISSN:
1029-8479
DOI:
10.1007/JHEP09(2019)028
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2019
detail.hit.zdb_id:
2027350-2
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