A search for the $\it{\Xi}^{++}_{cc}$ baryon through the $\it{\Xi}^{++}_{cc} \rightarrow D^{+} p K^{} \pi^{+}$ decay is performed with a data sample corresponding to an integrated luminosity of 1.7 $\mathrm{fb}^{1}$ recorded by the LHCb experiment in $pp$ collisions at a centreofmass energy of 13 TeV. No significant signal is observed in the mass range from the kinematic threshold of the decay to 3800 $\mathrm{MeV}/c^{2}$. An upper limit is set on the ratio of branching fractions $\mathcal{R} = \frac{\mathcal{B}(\it{\Xi}^{++}_{cc} \rightarrow D^{+} p K^{} \pi^{+})}{\mathcal{B}(\it{\Xi}^{++}_{cc} \rightarrow \Lambda^{+}_{c} K^{} \pi^{+}\pi^{+})}$ with $\mathcal{R} < 1.7 \hspace{2pt} (2.1) \times 10^{2}$ at the 90 (95) confidence level at the known mass of the $\it{\Xi}^{++}_{cc}$ state.
The Feynman diagram contributing to the inclusive (left) $\Xi _{ c c }^{++}\rightarrow D ^+ p K ^ \pi ^+ $ decay with the analogous (right) $\Xi _{ c c }^{++}\rightarrow \Lambda _ c ^+ K ^ \pi ^+ \pi ^+ $ diagram. 
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(left) Invariantmass distribution of the $ D ^+$ candidates after the full selection. The black points represent data and the fit is indicated by the continuous (blue) line with the individual signal and background components represented by the dotted (red) line and dashed (green) line, respectively. (right) Invariantmass distributions of rightsign (black) $ D ^+ p K ^ \pi ^+ $, wrongsignplus (red) $ D ^+ p K ^+ \pi ^+ $ and wrongsignminus (blue) $ D ^+ p K ^ \pi ^ $ data combinations are shown. The control samples have been normalised to the rightsign sample. 
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(left) Invariantmass distribution of the ${\Xi _{ c c }^{++}\rightarrow D ^+ p K ^ \pi ^+ }$ candidates with the fit overlaid. The black points represent data, the continuous (green) line represents the combinatorial background and the two vertical parallel dashed (blue) lines define the region where the signal is expected. (right) The local pvalue expressing the compatibility of the data with the backgroundonly hypothesis. The horizontal dashed (red) lines indicate pvalues of 1, 2 and 3$\sigma$ local significance. 
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Invariantmass distribution of the ${\Xi _{ c c }^{++}\rightarrow \Lambda _ c ^+ K ^ \pi ^+ \pi ^+ }$ candidates with the fit overlaid. The black points represent data, the dashed (green) line represents combinatorial background, the dotted (red) line represents the signal contribution and the continuous (blue) line is the total fit. 
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The scores from the \texttt{CLs} method for each value of the assumed ratio of branching fractions $\mathcal{R}$. Observed values are shown by the solid black line. The set upper limits at 90% and 95% CL are indicated by the dotted (blue) line and the dashed (red) line, respectively. 
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Animated gif made out of all figures. 
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Systematic and statistical uncertainties on the singleevent sensitivity $\alpha_{s}$. 
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Created on 27 February 2021.