cern.ch

Observation of the $B^+ \rightarrow J/\psi \eta^{\prime} K^+$ decay

[to restricted-access page]

Information

Tools

Abstract

The $B^+ \rightarrow J/\psi \eta^{\prime} K^+$ decay is observed for the first time using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8, and 13TeV, corresponding to a total integrated luminosity of 9fb$^{-1}$. The branching fraction of this decay is measured relative to the known branching fraction of the $B^+ \rightarrow \psi(2S) K^+$ decays and found to be $$ \frac{\mathcal{B}( B^+ \rightarrow J/\psi \eta^{\prime}K^+)}{\mathcal{B}( B^+ \rightarrow \psi(2S)K^+)} = \left(4.91\pm 0.47\pm0.29\pm0.07\right)\times10^{-2}, $$ where the first uncertainty is statistical, the second is systematic and the third is related to external branching fractions. A first look at the $J/\psi\eta^{\prime}$ mass distribution is performed and no signal of intermediate resonances is observed.

Figures and captions

Mass distributions for selected $ B ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \eta ^{\prime} K ^+ $ candidates with $\eta ^{\prime} $ decays to (left) $\rho ^0 \gamma $ and (right) $\eta \pi ^+ \pi ^- $ final states. The results of the fits, described in the text, are overlaid.

 Fig_1.pdf [133 KiB]
HiDef png [280 KiB]
Thumbnail [222 KiB]
*.C file
tex code 		Fig_1.pdf

Normalised backgrounddash-subtracted (a) $\eta ^{\prime} K ^+ $, (b) $ { J \mskip -3mu/\mskip -2mu\psi } \eta ^{\prime} $, (c) $ { J \mskip -3mu/\mskip -2mu\psi } K ^+ $ mass spectra and (d) twodash-dimensional mass distribution of $\eta ^{\prime} K ^+ $ vs $ { J \mskip -3mu/\mskip -2mu\psi } \eta ^{\prime} $ from the $ B ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \eta ^{\prime} K ^+ $ decays. Superimposed curves are the expectations from a phasedash-space model.

 Fig_2.pdf [169 KiB]
HiDef png [400 KiB]
Thumbnail [375 KiB]
*.C file
tex code 		Fig_2.pdf

Left: mass distributions for selected $ B ^+ \rightarrow \left(\psi {(2 S )} \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- \right) K ^+ $ decays, with $ { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- $ mass between 3.66 and 3.71 $\text{ Ge V /}c^2$ . Right: background-subtracted $ { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- $ mass distribution from selected $ B ^+$ decays. Results of the fits, described in the text, are overlaid.

 Fig_3.pdf [125 KiB]
HiDef png [217 KiB]
Thumbnail [175 KiB]
*.C file
tex code 		Fig_3.pdf

Animated gif made out of all figures.

 PAPER-2022-054.gif
Thumbnail
thumbnail_PAPER-2022-054.gif

Tables and captions

Summary of systematic uncertainties on the ratio of branching fractions $\mathcal{R}$. The overall systematic uncertainty is calculated as a sum in quadrature of all the sources.

 Table_1.pdf [48 KiB]
HiDef png [112 KiB]
Thumbnail [50 KiB]
tex code 		Table_1.pdf

Created on 08 December 2023.