Decays of beauty baryons to the $D^0 p h^-$ and $\Lambda_c^+ h^-$ final states (where $h$ indicates a pion or a kaon) are studied using a data sample of $pp$ collisions, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected by the LHCb detector. The Cabibbo-suppressed decays $\Lambda_b^0\to D^0 p K^-$ and $\Lambda_b^0\to \Lambda_c^+ K^-$ are observed and their branching fractions are measured with respect to the decays $\Lambda_b^0\to D^0 p \pi^-$ and $\Lambda_b^0\to \Lambda_c^+ \pi^-$. In addition, the first observation is reported of the decay of the neutral beauty-strange baryon $\Xi_b^0$ to the $D^0 p K^-$ final state, and a measurement of the $\Xi_b^0$ mass is performed. Evidence of the $\Xi_b^0\to \Lambda_c^+ K^-$ decay is also reported.
Distributions of invariant mass for (a) $\Lambda ^+_ c \pi ^- $ and (b) $ D ^0 p \pi ^- $ candidates passing the loose selection (points with error bars) and results of the fit (solid line). The signal and background contributions are shown. |
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Distributions of invariant mass for (a) $ D ^0 p \pi ^- $ and (b) $ D ^0 p K ^- $ candidates passing the tight selection (points with error bars) and results of the fit (solid line). The signal and background contributions are shown. |
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fig2b.pdf [20 KiB] HiDef png [437 KiB] Thumbnail [344 KiB] *.C file |
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Distributions of invariant mass for (a) $\Lambda ^+_ c \pi ^- $ and (b) $\Lambda ^+_ c K ^- $ candidates passing the tight selection (points with error bars) and results of the fit (solid line). The signal and background contributions are shown. The same distributions are magnified in (c) and (d) to better distinguish background components and $\Xi _{ b }^0 \rightarrow \Lambda ^+_ c K ^- $ signal. |
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fig3b.pdf [20 KiB] HiDef png [395 KiB] Thumbnail [303 KiB] *.C file |
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fig3c.pdf [18 KiB] HiDef png [419 KiB] Thumbnail [315 KiB] *.C file |
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Dalitz plot of $\Lambda ^0_ b \rightarrow D ^0 p \pi ^- $ candidates in (a) the full phase space region, and magnified regions of (b) low $M^2( D ^0 p )$ and (c) low $M^2( p \pi ^- )$. |
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Background-subtracted distributions of (a,b) $M( p \pi ^- )$ and (c,d) $M( D ^0 p )$ invariant masses in $\Lambda ^0_ b \rightarrow D ^0 p \pi ^- $ decays, where (b) and (d) are versions of (a) and (c), respectively, showing the lower invariant mass parts of the distributions. The distributions are not corrected for efficiency. |
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(a) $\Lambda ^0_ b \rightarrow D ^0 p K ^- $ Dalitz plot and background-subtracted distributions of (b) $M( p K ^- )$ and (c) $M( D ^0 p )$ invariant masses. The distributions are not corrected for efficiency. |
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Animated gif made out of all figures. |
PAPER-2013-056.gif Thumbnail |
Results of the fit to the invariant mass distribution of $\Lambda ^0_ b \rightarrow \Lambda ^+_ c \pi ^- $ and $\Lambda ^0_ b \rightarrow D ^0 p \pi ^- $ candidates passing the loose selection. The uncertainties are statistical only. |
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Results of the fit to the invariant mass distributions of $\Lambda ^0_ b \rightarrow \Lambda ^+_ c h^-$ and $\Lambda ^0_ b \rightarrow D ^0 p h^-$ candidates passing the tight selection. The uncertainties are statistical only. |
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Efficiency correction factors used to calculate the ratios of branching fractions. |
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Measured ratios of branching fractions, with their statistical and systematic uncertainties in units of $10^{-2}$. |
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Systematic uncertainties in the measurement of the mass difference $m_{\Xi _{ b }^0 }-m_{\Lambda ^0_ b }$. |
Table_5.pdf [30 KiB] HiDef png [43 KiB] Thumbnail [20 KiB] tex code |
dppics.{C,eps,pdf,png} - Distribution of "wrong-flavour" D0bar p pi invariant mass used to constrain background, and result of its fit. dpkcs.{C,eps,pdf,png} - Distribution of "wrong-flavour" D0bar p K invariant mass used to constrain background, and result of its fit. |
dpkcs.pdf [10 KiB] HiDef png [305 KiB] Thumbnail [259 KiB] *C file |
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dppics.pdf [9 KiB] HiDef png [234 KiB] Thumbnail [226 KiB] *C file |
Created on 02 May 2024.