Abstract

The Cabibbo-suppressed decay $\Lambda^0_b\rightarrow\psi(2S)p\pi^-$ is observed for the first time using a data sample collected by the LHCb experiment in proton-proton collisions corresponding to 1.0, 2.0 and 1.9fb$^{-1}$ of integrated luminosity at centre-of-mass energies of 7, 8 and 13TeV, respectively. The $\psi(2S)$ mesons are reconstructed in the $\mu^+\mu^-$ final state. The branching fraction with respect to that of the $\Lambda^0_b\rightarrow\psi(2S)pK^-$ decay mode is measured to be $$\frac{\mathcal{B}\left(\Lambda^0_b\rightarrow\psi(2S)p\pi^- \right)} {\mathcal{B}\left(\Lambda^0_b\rightarrow\psi(2S)pK^-\right)}=\left(11.4 \pm 1.3 \pm 0.2\right) \% ,$$ where the first uncertainty is statistical and the second is systematic. The $\psi(2S)p$ and $\psi(2S)\pi^-$ mass spectra are investigated and no evidence for exotic resonances is found.

Figures and captions

Mass distributions of the (left) $\Lambda ^0_ b \rightarrow \psi {(2 S )} p \pi ^- $ and (right) $\Lambda ^0_ b \rightarrow \psi {(2 S )} p K ^- $ candidates.	Fig_1.pdf [145 KiB] HiDef png [220 KiB] Thumbnail [189 KiB] *.C file tex code
Background-subtracted mass distributions of the (left) $\psi {(2 S )} p $ , (centre) $\psi {(2 S )} \pi ^- $ and (right) $ p \pi ^+ $ combinations in the $\Lambda ^0_ b \rightarrow \psi {(2 S )} p \pi ^- $ decay compared with distributions obtained from a phasedash-space simulation.	Fig_2.pdf [145 KiB] HiDef png [201 KiB] Thumbnail [194 KiB] *.C file tex code
Animated gif made out of all figures.	PAPER-2018-022.gif Thumbnail

Tables and captions

Relative systematic uncertainties for the ratio of branching fractions. The total uncertainty is the quadratic sum of the individual contributions.

Table_1.pdf [38 KiB] HiDef png [45 KiB] Thumbnail [21 KiB] tex code

Supplementary Material [file]

Supplementary material full pdf	supple[..].pdf [206 KiB]
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	Fig_supp2_.pdf [109 KiB] HiDef png [599 KiB] Thumbnail [170 KiB] *C file

Created on 27 April 2024.