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Search for the doubly charmed baryon ${\it{\Omega}_{cc}^{+}}$

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Abstract

A search for the doubly charmed baryon $\it{\Omega}_{cc}^{+}$ with the decay mode $\it{\Omega}_{cc}^{+}\to\it{\Xi}_c^{+}K^{-}\pi^{+}$ is performed using proton-proton collision data at a centre-of-mass energy of 13$\mathrm{ Te V}$ collected by the LHCb experiment from 2016 to 2018, corresponding to an integrated luminosity of $5.4 \mathrm{fb}^{-1}$. No significant signal is observed within the invariant mass range of 3.6 to 4.0$\mathrm{ Ge V}/c^2$. Upper limits are set on the ratio $R$ of the production cross-section times the total branching fraction of the $\it{\Omega}_{cc}^{+}\to\it{\Xi}_c^{+}K^{-}\pi^{+}$ decay with respect to the $\it{\Xi}_{cc}^{++}\to\it{\Lambda}_c^{+}K^{-}\pi^{+}\pi^{+}$ decay. Upper limits at 95 credibility level for $R$ in the range $0.005$ to $0.11$ are obtained for different hypotheses on the $\it{\Omega}_{cc}^{+}$ mass and lifetime in the rapidity range from 2.0 to 4.5 and transverse momentum range from 4 to 15$\mathrm{ Ge V}/c$.

Figures and captions

Example Feynman diagram for the $\Omega ^{+}_{ c c } \rightarrow \Xi ^+_ c K ^- \pi ^+ $ decay.

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Invariant mass $m(\Xi ^+_ c K ^- \pi ^+ )$ distribution of selected $\Omega ^{+}_{ c c }$ candidates from (black points) selection A, with (blue solid line) the fit with the largest local significance at the mass of 3876 $\text{ Me V /}c^2$ superimposed.

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Local $p$-value at different $m(\Omega ^{+}_{ c c } )$ values evaluated with the likelihood ratio test. Lines indicating one, two and three standard deviations ($\sigma$) of local significance are also shown.

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Invariant mass $m(\Xi ^+_ c K ^- \pi ^+ )$ distribution of selected $\Omega ^{+}_{ c c }$ candidates (black points) with selection B, only background fit is shown.

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Distribution of invariant mass $m(\Lambda ^+_ c K ^- \pi ^+ \pi ^+ )$ for selected $\Xi ^{++}_{ c c } $ candidates in different categories: (a) triggered by one of the $\Lambda ^+_ c $ decay products and (b) triggered exclusively by particles unrelated to the $\Xi ^{++}_{ c c }$ decay products, in the 2018 data set. The fit results are superimposed.

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Upper limits on the production ratio $R$ at 95% credibility level as a function of $m(\Xi ^+_ c K ^- \pi ^+ )$ at $\sqrt{s}=13\text{ Te V} $, for five $\Omega ^{+}_{ c c } $ lifetime hypotheses.

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Animated gif made out of all figures.

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Tables and captions

Signal yields for the $\Xi ^{++}_{ c c } \rightarrow \Lambda ^+_ c K ^- \pi ^+ \pi ^+ $ normalisation mode $N_{\text{norm}}$ for both trigger categories and different data-taking periods with the corresponding integrated luminosity $\mathcal{L}$. The uncertainties are statistical only.

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Efficiency ratios $\varepsilon _{\rm norm}/\varepsilon _{\rm sig}$ between normalisation and signal modes for both trigger categories for different data-taking periods, where the TOS refers to the trigger on signal and the exTIS refers to exclusive trigger independently of signal. The uncertainties are statistical only.

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Single-event sensitivity $\alpha(\Xi ^{++}_{ c c } )$ [$10^{-2}$] of the $\Xi ^{++}_{ c c }$ normalisation mode triggered by one of the $\Xi ^+_ c $ ( $\Lambda ^+_ c $ ) products for different lifetime hypotheses of the $\Omega ^{+}_{ c c } $ baryon for different data-taking periods. The uncertainties are due to the limited size of the simulated samples and the statistical uncertainties on the measured $\Xi ^{++}_{ c c }$ baryon yields.

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Single-event sensitivity $\alpha(\Xi ^{++}_{ c c } )$ [$10^{-2}$] of the $\Xi ^{++}_{ c c }$ normalisation mode triggered exclusively by particles unrelated to the $\Omega ^{+}_{ c c }$ ( $\Xi ^{++}_{ c c }$ ) decay products for different lifetime hypotheses of the $\Omega ^{+}_{ c c } $ baryon in the different data-taking periods. The uncertainties are due to the limited size of the simulated samples and the statistical uncertainty on the measured $\Xi ^{++}_{ c c }$ baryon yield.

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Systematic uncertainties on the production ratio $R$.

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Supplementary Material [file]

Supplementary material full pdf

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This ZIP file contains supplemetary material for the publication LHCb-PAPER-2021-011. The files are: Supplementary.pdf : An overview of the extra figures *.pdf, *.png, *.eps : The figures in variuous formats

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Created on 27 April 2024.