Observation of the Λ<sub>b</sub><SUP>0</SUP> → χ<sub>c1</sub> (3872)pK<SUP>-</SUP> decay



Aaij, R, Beteta, C Abellan, Adeva, B, Adinolfi, M, Aidala, CA, Ajaltouni, Z, Akar, S, Albicocco, P, Albrecht, J, Alessio, F
et al (show 834 more authors) (2019) Observation of the Λ<sub>b</sub><SUP>0</SUP> → χ<sub>c1</sub> (3872)pK<SUP>-</SUP> decay. JOURNAL OF HIGH ENERGY PHYSICS, 09 (9). 028-.

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Abstract

Using proton-proton collision data, collected with the LHCb detector and corresponding to 1.0, 2.0 and 1.9fb$^{-1}$ of integrated luminosity at the centre-of-mass energies of 7, 8, and 13 TeV, respectively, the decay $\Lambda_b^0\to \chi_{c1}(3872)pK^-$ with $\chi_{c1}\to J/\psi\pi^+\pi^-$ is observed for the first time. The significance of the observed signal is in excess of seven standard deviations. It is found that $(58\pm15)\%$ of the decays proceed via the two-body intermediate state $\chi_{c1}(3872)\Lambda(1520)$. The~branching fraction with respect to that of the $\Lambda_b\rightarrow\psi(2S)p K^{-}$ decay mode, where the $\psi(2S)$~meson is reconstructed in the $J/\psi \pi^+\pi^-$ final state, is measured to be: \begin{equation*} \frac{\Lambda_b^0\to\chi_{c1}(3872)pK^-}{\Lambda_b\to\psi(2S)p K^-} \times \frac{\mathcal{B}(\chi_{c1} \to J/\psi \pi^+\pi^-)}{\mathcal{B}(\psi(2S)\to J/\psi \pi^+\pi^-)} = \left(5.4 \pm 1.1 \pm 0.2\right)\times 10^{-2}\,, \end{equation*} where the first uncertainty is statistical and the second is systematic.

Item Type: Article
Additional Information: 19 pages, 2 figures. All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2019-023.html
Uncontrolled Keywords: B physics, Branching fraction, Exotics, Hadron-Hadron scattering (experiments)
Depositing User: Symplectic Admin
Date Deposited: 05 Dec 2019 15:45
Last Modified: 08 Oct 2023 21:44
DOI: 10.1007/JHEP09(2019)028
Open Access URL: https://doi.org/10.1007/JHEP09(2019)028
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3064999