Observation of the decay $\overline{B_s^0} \rightarrow \chi_{c2} K^+ K^- $ in the $\phi$ mass region

Information

LHCb-PAPER-2018-018
CERN-EP-2018-160
arXiv:1806.10576 [PDF]

(Submitted on 27 Jun 2018)
JHEP 08 (2018) 191
Inspire 1680225

Tools

Abstract

The $\overline{B_s^0} \rightarrow \chi_{c2} K^+ K^- $ decay mode is observed and its branching fraction relative to the corresponding $\chi_{c1}$ decay mode, in a $\pm 15 \textrm{MeV}/c^2$ window around the $\phi$ mass, is found to be $\frac{\mathcal{B}(\overline{B_s^0} \rightarrow \chi_{c2} K^+ K^-) }{ \mathcal{B}(\overline{B_s^0} \rightarrow \chi_{c1} K^+ K^-)} = (17.1 \pm 3.1 \pm 0.4 \pm 0.9)\%,$ where the first uncertainty is statistical, the second systematic and the third due to the knowledge of the branching fractions of radiative $\chi_c$ decays. The decay mode $\overline{B_s^0} \rightarrow \chi_{c1} K^+ K^- $ allows the $ B_s^0$ mass to be measured as $m(B_s^0) = 5366.83 \pm 0.25 \pm 0.27 \textrm{MeV}/c^2,$ where the first uncertainty is statistical and the second systematic. A combination of this result with other LHCb determinations of the $B_s^0$ mass is made.

Figures and captions

Tree-level Feynman diagram for the $\overline{ B }{} {}^0_ s \rightarrow \chi_{cJ} \phi$ decay mode.	fig1.pdf [78 KiB] HiDef png [32 KiB] Thumbnail [15 KiB] *.C file
Invariant-mass distributions of (left) $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \gamma$ and (right) $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \gamma K^+ K^-$ after the loose selection criteria.	fig2a.pdf [11 KiB] HiDef png [86 KiB] Thumbnail [48 KiB] *.C file
	fig2b.pdf [11 KiB] HiDef png [89 KiB] Thumbnail [49 KiB] *.C file
MLP response for (solid yellow) the $\overline{ B }{} {}^0_ s \rightarrow \chi _{ c 1} K^+ K^-$ simulation sample, (hashed blue) high-mass sideband and (black points) the background subtracted $\overline{ B }{} {}^0_ s \rightarrow \chi _{ c 1} K^+ K^-$ signal in data. The histogram areas are normalized to the number of $\overline{ B }{} {}^0_ s \rightarrow \chi _{ c 1} K^+ K^-$ candidates observed in data after the loose selection. The arrow indicates the selected threshold.	fig3.pdf [9 KiB] HiDef png [249 KiB] Thumbnail [189 KiB] *.C file
Invariant-mass distributions of selected candidates for (left) the $\chi _{ c 1} K^+ K^-$ fit and (right) the $\chi _{ c 2} K^+ K^-$ fit. The total fitted function is superimposed (solid red line) together with the (blue hashed area) $\chi _{ c 1} $ component, (solid yellow) $\chi _{ c 2} $ component and (dashed black line) the background component. The pull, i.e. the difference between the observed and fitted value divided by the uncertainty, is shown below each of the plots.	fig4a.pdf [13 KiB] HiDef png [282 KiB] Thumbnail [205 KiB] *.C file
	fig4b.pdf [12 KiB] HiDef png [371 KiB] Thumbnail [260 KiB] *.C file
Invariant-mass distribution of the $K^+K^-$ pair for the (left) $\overline{ B }{} {}^0_ s \rightarrow \chi _{ c 1} K^+ K^-$ decay obtained with the $\chi _{ c 1} $ mass constraint applied to the $ B ^0_ s $ candidate invariant mass and (right) $\overline{ B }{} {}^0_ s \rightarrow \chi _{ c 2} K^+ K^-$ decay obtained with the $\chi _{ c 2} $ mass constraint applied to the $ B ^0_ s $ candidate invariant mass. The (red solid line) total fitted function is superimposed together with (blue hashed area) the S-wave component.	fig5a.pdf [14 KiB] HiDef png [226 KiB] Thumbnail [178 KiB] *.C file
	fig5b.pdf [13 KiB] HiDef png [177 KiB] Thumbnail [161 KiB] *.C file
Animated gif made out of all figures.	PAPER-2018-018.gif Thumbnail

Tables and captions

Results of the $\chi _{ c 1} K^+ K^-$ and $\chi _{ c 2} K^+ K^-$ fits to the invariant-mass distributions. A Gaussian constraint is applied to the $s_f$ parameter.	Table_1.pdf [76 KiB] HiDef png [77 KiB] Thumbnail [36 KiB] tex code
Systematic uncertainties for the measurement of the ratio $\mathcal{B}(\overline{ B }{} {}^0_ s \rightarrow \chi _{ c 2} K^+ K^-)/\mathcal{B}(\overline{ B }{} {}^0_ s \rightarrow \chi _{ c 1} K^+ K^-)$.	Table_2.pdf [70 KiB] HiDef png [64 KiB] Thumbnail [29 KiB] tex code
Systematic uncertainties on the $ B ^0_ s $ mass measurement.	Table_3.pdf [51 KiB] HiDef png [83 KiB] Thumbnail [36 KiB] tex code

Supplementary Material [file]

Supplementary material full pdf	supple[..].pdf [195 KiB]
This ZIP file contains supplemetary material for the publication LHCb-PAPER-2018-018. The files are: Supplementary.pdf : An overview of the extra figures .pdf, .png, *.eps : The figures in variuous formats	fig6a.pdf [13 KiB] HiDef png [101 KiB] Thumbnail [56 KiB] *C file
	fig6b.pdf [13 KiB] HiDef png [112 KiB] Thumbnail [62 KiB] *C file
	fig7.pdf [10 KiB] HiDef png [102 KiB] Thumbnail [77 KiB] *C file
	fig8.pdf [10 KiB] HiDef png [97 KiB] Thumbnail [78 KiB] *C file