cern.ch

Measurements of the branching fractions of $\Lambda_{c}^{+} \rightarrow p \pi^{-} \pi^{+}$, $\Lambda_{c}^{+} \rightarrow p K^{-} K^{+}$, and $\Lambda_{c}^{+} \rightarrow p \pi^{-} K^{+}$

[to restricted-access page]

Information

Tools

Abstract

The ratios of the branching fractions of the decays $\Lambda_{c}^{+} \rightarrow p \pi^{-} \pi^{+}$, $\Lambda_{c}^{+} \rightarrow p K^{-} K^{+}$, and $\Lambda_{c}^{+} \rightarrow p \pi^{-} K^{+}$ with respect to the Cabibbo-favoured $\Lambda_{c}^{+} \rightarrow p K^{-} \pi^{+}$ decay are measured using proton-proton collision data collected with the LHCb experiment at a 7 TeV centre-of-mass energy and corresponding to an integrated luminosity of 1.0 fb$^{-1}$: \begin{align*} \frac{\mathcal{B}(\Lambda_{c}^{+} \rightarrow p \pi^{-} \pi^{+})}{\mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} \pi^{+})} & = (7.44 \pm 0.08 \pm 0.18) \%, \frac{\mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} K^{+})}{\mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} \pi^{+})} &= (1.70 \pm 0.03 \pm 0.03) \%, \frac{\mathcal{B}(\Lambda_{c}^{+} \rightarrow p \pi^{-} K^{+})}{\mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} \pi^{+})} & = (0.165 \pm 0.015 \pm 0.005 ) \%, \end{align*} where the uncertainties are statistical and systematic, respectively. These results are the most precise measurements of these quantities to date. When multiplied by the world-average value for $\mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} \pi^{+})$, the corresponding branching fractions are \begin{align*} \mathcal{B}(\Lambda_{c}^{+} \rightarrow p \pi^{-} \pi^{+}) &= (4.72 \pm 0.05 \pm 0.11 \pm 0.25) \times 10^{-3}, \mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} K^{+}) &= (1.08 \pm 0.02 \pm 0.02 \pm 0.06) \times 10^{-3}, \mathcal{B}(\Lambda_{c}^{+} \rightarrow p \pi^{-} K^{+}) &= (1.04 \pm 0.09 \pm 0.03 \pm 0.05) \times 10^{-4}, \end{align*} where the final uncertainty is due to $\mathcal{B}(\Lambda_{c}^{+} \rightarrow p K^{-} \pi^{+})$.

Figures and captions

Weak decays of $\Lambda ^+_ c $ to a proton and two mesons, without hyperon mediation. Shown are external $ W $ -emission for (a) $\Lambda ^+_ c \rightarrow p K ^- \pi ^+ $ and (b) $\Lambda ^+_ c \rightarrow p \pi ^- K ^+ $ , internal $ W $ -emission for (c) $\Lambda ^+_ c \rightarrow p K ^- \pi ^+ $ and (d) $\Lambda ^+_ c \rightarrow p \pi ^- K ^+ $ , and $ W $ -exchange for (e) $\Lambda ^+_ c \rightarrow p K ^- \pi ^+ $ .

 [Failure to get the plot]

Invariant mass distributions of (a) $\Lambda ^+_ c \rightarrow p K ^- \pi ^+ $ , (b) $\Lambda ^+_ c \rightarrow p \pi ^- \pi ^+ $ , (c) $\Lambda ^+_ c \rightarrow p K ^- K ^+ $ , and (d) $\Lambda ^+_ c \rightarrow p \pi ^- K ^+ $ decays, with fit results superimposed. The hatched magenta region indicates the signal, the shaded green region indicates the background from unrelated tracks, and the solid red line indicates the full fit.

 Fig2a.pdf [17 KiB]
HiDef png [460 KiB]
Thumbnail [264 KiB]
*.C file
Fig2a.pdf
Fig2b.pdf [17 KiB]
HiDef png [492 KiB]
Thumbnail [271 KiB]
*.C file
Fig2b.pdf
Fig2c.pdf [17 KiB]
HiDef png [375 KiB]
Thumbnail [236 KiB]
*.C file
Fig2c.pdf
Fig2d.pdf [16 KiB]
HiDef png [343 KiB]
Thumbnail [218 KiB]
*.C file
Fig2d.pdf

Invariant mass distributions for (a) $\Lambda ^+_ c \rightarrow p K ^- \pi ^+ $ , (c) $\Lambda ^+_ c \rightarrow p \pi ^- \pi ^+ $ , (e) $\Lambda ^+_ c \rightarrow p K ^- K ^+ $ in the prompt analysis, with fit results superimposed. The $\ln \left(\chi^2 _{\mathrm{IP} } \right)$ distributions for (b) $\Lambda ^+_ c \rightarrow p K ^- \pi ^+ $ , (d) $\Lambda ^+_ c \rightarrow p \pi ^- \pi ^+ $ , (f) $\Lambda ^+_ c \rightarrow p K ^- K ^+ $ , with the fit results superimposed, showing the differentiation of prompt and secondary $\Lambda ^+_ c $ .

 Fig3a.pdf [17 KiB]
HiDef png [446 KiB]
Thumbnail [253 KiB]
*.C file
Fig3a.pdf
Fig3b.pdf [17 KiB]
HiDef png [244 KiB]
Thumbnail [176 KiB]
*.C file
Fig3b.pdf
Fig3c.pdf [16 KiB]
HiDef png [215 KiB]
Thumbnail [157 KiB]
*.C file
Fig3c.pdf
Fig3d.pdf [19 KiB]
HiDef png [220 KiB]
Thumbnail [162 KiB]
*.C file
Fig3d.pdf
Fig3e.pdf [16 KiB]
HiDef png [283 KiB]
Thumbnail [195 KiB]
*.C file
Fig3e.pdf
Fig3f.pdf [16 KiB]
HiDef png [230 KiB]
Thumbnail [178 KiB]
*.C file
Fig3f.pdf

Animated gif made out of all figures.

 PAPER-2017-026.gif
Thumbnail
thumbnail_PAPER-2017-026.gif

Tables and captions

Selection efficiency ratios in the prompt and SL measurements, with their associated systematic uncertainties. $\epsilon_{\mathrm{CF}} / \epsilon_{\mathrm{CS}} $ denotes the ratio of the Cabibbo-favoured selection efficiency over that of the Cabibbo-suppressed mode.

 Table_1.pdf [67 KiB]
HiDef png [69 KiB]
Thumbnail [35 KiB]
tex code 		Table_1.pdf

Signal yields in both the SL and prompt measurements.

 Table_2.pdf [65 KiB]
HiDef png [83 KiB]
Thumbnail [43 KiB]
tex code 		Table_2.pdf

Relative systematic uncertainties in each ratio of branching fractions, for the SL analysis.

 Table_3.pdf [69 KiB]
HiDef png [40 KiB]
Thumbnail [17 KiB]
tex code 		Table_3.pdf

Relative systematic uncertainties in each ratio of branching fractions, for the prompt analysis.

 Table_4.pdf [68 KiB]
HiDef png [48 KiB]
Thumbnail [22 KiB]
tex code 		Table_4.pdf

Created on 27 April 2024.