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Observation of five new narrow $\Omega_c^0$ states decaying to $\Xi^+_c K^-$

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Abstract

The $\Xi_c^+ K^-$ mass spectrum is studied with a sample of $pp$ collision data corresponding to an integrated luminosity of 3.3 fb$^{-1}$, collected by the LHCb experiment. The $\Xi_c^+$ is reconstructed in the decay mode $p K^- \pi^+$. Five new, narrow excited $\Omega_c^0$ states are observed: the $\Omega_c(3000)^0$, $\Omega_c(3050)^0$, $\Omega_c(3066)^0$, $\Omega_c(3090)^0$, and $\Omega_c(3119)^0$. Measurements of their masses and widths are reported.

Figures and captions

Distribution of the reconstructed invariant mass $m( p K ^- \pi ^+ )$ for all candidates in the inclusive $\Xi ^+_ c $ sample passing the likelihood ratio selection described in the text. The solid (red) curve shows the result of the fit, and the dashed (blue) line indicates the fitted background.

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Distribution of the reconstructed invariant mass $m(\Xi ^+_ c K ^- )$ for all candidates passing the likelihood ratio selection; the solid (red) curve shows the result of the fit, and the dashed (blue) line indicates the fitted background. The shaded (red) histogram shows the corresponding mass spectrum from the $\Xi ^+_ c $ sidebands and the shaded (light gray) distributions indicate the feed-down from partially reconstructed $\POmega _ c (X)^0$ resonances.

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Distribution of the reconstructed invariant mass $m(\Xi ^+_ c K ^- )$ for all candidates passing the likelihood ratio selection, shown as black points with error bars, and the wrong-sign $m(\Xi ^+_ c K ^+ )$ spectrum scaled by a factor of 0.95, shown as a solid (red) histogram.

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Animated gif made out of all figures.

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Tables and captions

Results of the fit to $m(\Xi ^+_ c K ^- )$ for the mass, width, yield and significance for each resonance. The subscript "${\rm fd}$" indicates the feed-down contributions described in the text. For each fitted parameter, the first uncertainty is statistical and the second systematic. The asymmetric uncertainty on the $\POmega _ c (X)^0$ arising from the $\Xi ^+_ c $ mass is given separately. Upper limits are also given for the resonances $\POmega _ c (3050)^0$ and $\POmega _ c (3119)^0$ for which the width is not significant.

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tex code
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Supplementary Material [file]

Supplementary material full pdf

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supplementary.pdf

This ZIP file contains supplemetary material for the publication LHCb-PAPER-2017-002. The files are: supplementary.pdf : An overview of the extra figures *.pdf, *.png, *.eps, *.C : The figures in variuous formats

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Created on 17 December 2018.Citation count from INSPIRE on 18 December 2018.