Observation of the $B_s^0\to {\chi }_{c1}(3872){\pi }^{+}{\pi }^{-}$ decay

Abstract

The first observation of the $B_s^0\to \left({\chi }_{c1}(3872)\to J/\psi {\pi }^{+}{\pi }^{-}\right){\pi }^{+}{\pi }^{-}$ decay is reported using proton-proton collision data, corresponding to integrated luminosities of 1, 2 and 6fb${}^{-1}$, collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13TeV, respectively. The ratio of branching fractions relative to the $B_s^0\to \left(\psi (2S)\to J\psi {\pi }^{+}{\pi }^{-}\right){\pi }^{+}{\pi }^{-}$ decay is measured to be $$\frac{\mathcal{B}\left(B_s^0\to {\chi }_{c1}(3872){\pi }^{+}{\pi }^{-}\right)\times \mathcal{B}\left({\chi }_{c1}(3872)\to J\psi {\pi }^{+}{\pi }^{-}\right)}{\mathcal{B}\left(B_s^0\to \psi (2S){\pi }^{+}{\pi }^{-}\right)\times \mathcal{B}\left(\psi (2S)\to J\psi {\pi }^{+}{\pi }^{-}\right)}=\left(6.8\pm 1.1\pm 0.2\right)\times 10^{-2},$$ where the first uncertainty is statistical and the second systematic. The mass spectrum of the ${\pi }^{+}{\pi }^{-}$ system recoiling against the ${\chi }_{c1}(3872)$ meson exhibits a large contribution from $B_s^0\to {\chi }_{c1}(3872)\left(f_0(980)\to {\pi }^{+}{\pi }^{-}\right)$ decays.

arXiv comment16 pages, 2 figures. All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-049.html (LHCb public pages)

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Cited by in corpus (1)

• Modification of ${\chi }_{c1}$(3872) and $\psi$(2$S$) production in $p$Pb collisions at $\sqrt{s_{NN}}=8.16$ TeV