Using $pp$ collisions corresponding to 3$ \text{fb}^{-1}$ integrated luminosity, recorded by the LHCb experiment at centre-of-mass energies of 7 and 8$ \text{TeV}$, the ratio of branching fractions \begin{align*} \mathcal{B}(\Lambda^0_b \to\psi(2S) \Lambda )/\mathcal{B}(\Lambda^0_b \to J/\psi \Lambda)= 0.513 \pm 0.023 (\text{stat}) \pm 0.016 (\text{syst}) \pm 0.011 (\mathcal{B}) \end{align*} is determined. The first uncertainty is statistical, the second is systematic and the third is due to the external branching fractions used.
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Interpolated efficiency function for long-track candidates for (a) $\Lambda ^0_ b \rightarrow \psi {(2S)} \Lambda $ and (b) $\Lambda ^0_ b \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \Lambda $ and for downstream-track candidates for (c) $\Lambda ^0_ b \rightarrow \psi {(2S)} \Lambda $ and (d) $\Lambda ^0_ b \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \Lambda $ candidates. The distribution of the candidates on data is shown with black dots (each dot refers to one candidate). Statistical fluctuations of the simulated sample are contributing to the efficiency function at the phase-space boundaries, where data candidates are not affected. |
Fig1a.pdf [59 KiB] HiDef png [886 KiB] Thumbnail [631 KiB] *.C file |
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Fig1b.pdf [107 KiB] HiDef png [1 MiB] Thumbnail [686 KiB] *.C file |
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Fig1c.pdf [77 KiB] HiDef png [1 MiB] Thumbnail [649 KiB] *.C file |
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Fig1d.pdf [268 KiB] HiDef png [1 MiB] Thumbnail [721 KiB] *.C file |
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Fits to the (unweighted) invariant-mass distributions of long-track candidates for (a) $\Lambda ^0_ b \rightarrow \psi {(2S)} \Lambda $ and (b) $\Lambda ^0_ b \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \Lambda $ and for downstream-track candidates for (c) $\Lambda ^0_ b \rightarrow \psi {(2S)} \Lambda $ and (d) $\Lambda ^0_ b \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \Lambda $ candidates. The signal (blue, dashed), the combinatorial background (green, dotted), the $ B ^0 \rightarrow \psi K ^0_{\mathrm{ \scriptscriptstyle S}} $ background (cyan, long-dash-dotted) and the $\Xi ^-_ b \rightarrow \psi \Xi ^- $ background (violet, dash-triple-dotted) are indicated. |
Fig2a.pdf [20 KiB] HiDef png [309 KiB] Thumbnail [169 KiB] *.C file |
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Fig2b.pdf [21 KiB] HiDef png [314 KiB] Thumbnail [167 KiB] *.C file |
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Fig2c.pdf [34 KiB] HiDef png [403 KiB] Thumbnail [218 KiB] *.C file |
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Fig2d.pdf [36 KiB] HiDef png [375 KiB] Thumbnail [199 KiB] *.C file |
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Fits to the weighted invariant-mass distributions of long-track candidates for (a) $\Lambda ^0_ b \rightarrow \psi {(2S)} \Lambda $ and (b) $\Lambda ^0_ b \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \Lambda $ and for downstream-track candidates for (c) $\Lambda ^0_ b \rightarrow \psi {(2S)} \Lambda $ and (d) $\Lambda ^0_ b \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \Lambda $ candidates. The signal (blue, dashed), the combinatorial background (green, dotted), the $ B ^0 \rightarrow \psi K ^0_{\mathrm{ \scriptscriptstyle S}} $ background (cyan, long-dash-dotted) and the $\Xi ^-_ b \rightarrow \psi \Xi ^- $ background (violet, dash-triple-dotted) are indicated. |
Fig3a.pdf [21 KiB] HiDef png [327 KiB] Thumbnail [179 KiB] *.C file |
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Fig3b.pdf [21 KiB] HiDef png [332 KiB] Thumbnail [175 KiB] *.C file |
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Fig3c.pdf [36 KiB] HiDef png [403 KiB] Thumbnail [216 KiB] *.C file |
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Fig3d.pdf [37 KiB] HiDef png [387 KiB] Thumbnail [200 KiB] *.C file |
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Animated gif made out of all figures. |
PAPER-2017-041.gif Thumbnail |
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Yields from the invariant-mass fits in the range 5350 to 5750 $ {\mathrm{ Me V /}c^2}$ of (top) $\Lambda ^0_ b \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \Lambda $ decays and (bottom) $\Lambda ^0_ b \rightarrow \psi {(2S)} \Lambda $ decays for each component. |
Table_1.pdf [95 KiB] HiDef png [51 KiB] Thumbnail [23 KiB] tex code |
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Efficiency-corrected yields of $\Lambda ^0_ b \rightarrow \psi {(2S)} \Lambda $ and $\Lambda ^0_ b \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \Lambda $ signal decays from the fit to the weighted invariant mass for both track types. |
Table_2.pdf [102 KiB] HiDef png [45 KiB] Thumbnail [20 KiB] tex code |
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Relative systematic uncertainties on the ratio of branching fractions. |
Table_3.pdf [71 KiB] HiDef png [127 KiB] Thumbnail [58 KiB] tex code |
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Created on 10 August 2024.