Observation of the Λb0→χc1$$ {\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1} $$ (3872) pK− decay
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Author(s)
Aaij, R.
Abellán Beteta, C.
Ackernley, T.
Adeva, B.
Adinolfi, M.
Aidala, C. A
Aiola, S.
Ajaltouni, Z.
Akar, S.
Albicocco, P.
Date Issued
September 3, 2019
Publisher
Springer Berlin Heidelberg
Citation
Journal of High Energy Physics. 2019 Sep 03;2019(9):28
Version
Final published version
Abstract
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 Λb0→χc1$$ {\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1} $$(3872)pK− with χc1(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 χc1(3872)Λ(1520). The branching fraction with respect to that of the Λb0$$ {\Lambda}_{\mathrm{b}}^0 $$ → ψ(2S)pK− decay mode, where the ψ(2S) meson is reconstructed in the J/ψ π+π− final state, is measured to be:βΛb0→χc13872pK−βΛb0→ψ2SpK−×βχc13872→J/ψπ+π−βψ2S→J/ψπ+π−=5.4±1.1±0.2×10−2,$$ \frac{\beta \left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1}(3872){\mathrm{pK}}^{-}\right)}{\beta \left({\Lambda}_{\mathrm{b}}^0\to \uppsi \left(2\mathrm{S}\right){\mathrm{pK}}^{-}\right)}\times \frac{\beta \left({\upchi}_{\mathrm{c}1}(3872)\to \mathrm{J}/\uppsi {\uppi}^{+}{\uppi}^{-}\right)}{\beta \left(\uppsi \left(2\mathrm{S}\right)\to \mathrm{J}/\uppsi {\uppi}^{+}{\uppi}^{-}\right)}=\left(5.4\pm 1.1\pm 0.2\right)\times {10}^{-2}, $$
where the first uncertainty is statistical and the second is systematic.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1007/JHEP09(2019)028
