A search is performed for the as yet unobserved baryonic $\Lambda_b \rightarrow \Lambda \eta^\prime$ and $\Lambda_b \rightarrow \Lambda \eta$ decays with 3$fb^{-1}$ of proton-proton collision data recorded by the LHCb experiment. The $B^0 \rightarrow K_S^0 \eta^\prime$ decay is used as a normalisation channel. No significant signal is observed for the $\Lambda_b \rightarrow \Lambda \eta^\prime$ decay. An upper limit is found on the branching fraction of $\mathcal{B}(\Lambda_b \rightarrow \Lambda \eta^\prime)<3.1\times10^{-6}$} at 90% confidence level. Evidence is seen for the presence of the $\Lambda_b \rightarrow \Lambda \eta$ decay at the level of $3\sigma$ significance, with a branching fraction $\mathcal{B}(\Lambda_b \rightarrow \Lambda \eta)=(9.3^{+7.3}_{-5.3})\times10^{-6}$}.
Feynman diagrams for the $\Lambda ^0_ b \rightarrow \Lambda \eta ^{(\prime)} $ decay. The non-spectator and anomalous diagrams are available only to the $\eta ^{\prime}$ through the gluonic contribution. |
LbEtap[..].png [30 KiB] HiDef png [58 KiB] Thumbnail [26 KiB] *.C file |
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LbEtap[..].png [49 KiB] HiDef png [87 KiB] Thumbnail [42 KiB] *.C file |
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LbEtap[..].png [38 KiB] HiDef png [64 KiB] Thumbnail [30 KiB] *.C file |
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Mass distribution of the selected $ B ^0 \rightarrow K ^0_{\rm\scriptscriptstyle S} \eta ^{\prime} $ ( $\eta ^{\prime} \rightarrow \pi ^+ \pi ^- \gamma$ ) candidates in the 2011 and 2012 data, reconstructed in the L (left) and D (right) categories. The results of the fit, as described in the text, are overlaid. |
Fig2a.pdf [19 KiB] HiDef png [250 KiB] Thumbnail [189 KiB] *.C file |
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Fig2b.pdf [19 KiB] HiDef png [241 KiB] Thumbnail [185 KiB] *.C file |
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Mass distribution of the reconstructed $\eta ^{\prime}$ meson for selected $ B ^0 \rightarrow K ^0_{\rm\scriptscriptstyle S} \eta ^{\prime} $ ( $\eta ^{\prime} \rightarrow \pi ^+ \pi ^- \gamma$ ) candidates, in the L (left) and D (right) categories. The results of the fit, as described in the text, are overlaid. |
Fig3a.pdf [18 KiB] HiDef png [234 KiB] Thumbnail [174 KiB] *.C file |
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Fig3b.pdf [18 KiB] HiDef png [246 KiB] Thumbnail [183 KiB] *.C file |
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Mass distribution of the selected $\Lambda ^0_ b \rightarrow \Lambda \eta ^{\prime} $ ( $\eta ^{\prime} \rightarrow \pi ^+ \pi ^- \gamma$ ) candidates in the 2011 and 2012 data, reconstructed in the L (left) and D (right) categories. The results of the fit, as described in the text, are overlaid. |
Fig4a.pdf [17 KiB] HiDef png [193 KiB] Thumbnail [155 KiB] *.C file |
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Fig4b.pdf [18 KiB] HiDef png [205 KiB] Thumbnail [163 KiB] *.C file |
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Mass distribution of the selected $\Lambda ^0_ b \rightarrow \Lambda \eta ^{\prime} $ ( $\eta ^{\prime} \rightarrow \pi ^+ \pi ^- \eta $ ) candidates in the 2011 and 2012 data, reconstructed in the L (left) and D (right) categories. The results of the fit, as described in the text, are overlaid. |
Fig5a.pdf [17 KiB] HiDef png [191 KiB] Thumbnail [149 KiB] *.C file |
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Fig5b.pdf [16 KiB] HiDef png [181 KiB] Thumbnail [141 KiB] *.C file |
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Mass distribution of the selected $\Lambda ^0_ b \rightarrow \Lambda \eta $ ( $\eta \rightarrow \pi ^+ \pi ^- \pi ^0 $ ) candidates in the 2011 and 2012 data, reconstructed in the L (left) and D (right) categories. The results of the fit, as described in the text, are overlaid. |
Fig6a.pdf [16 KiB] HiDef png [179 KiB] Thumbnail [138 KiB] *.C file |
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Fig6b.pdf [17 KiB] HiDef png [203 KiB] Thumbnail [150 KiB] *.C file |
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Animated gif made out of all figures. |
PAPER-2015-019.gif Thumbnail |
Components contributing to the scale factor $\alpha.$ |
Table_1.pdf [75 KiB] HiDef png [58 KiB] Thumbnail [28 KiB] tex code |
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Fractional systematic uncertainties, in percent, on the ratio of branching fractions. |
Table_2.pdf [78 KiB] HiDef png [83 KiB] Thumbnail [42 KiB] tex code |
Created on 18 May 2024.