The ratio of the $B^0_s$ and $B^0$ fragmentation fractions, $f_s/f_d$, in proton-proton collisions at the LHC, is obtained as a function of $B$-meson transverse momentum and collision centre-of-mass energy from the combined analysis of different $B$-decay channels measured by the LHCb experiment. The results are described by a linear function of the meson transverse momentum, or with a function inspired by Tsallis statistics. Precise measurements of the branching fractions of the $B^0_s \to J/\psi \phi$ and $B^0_s \to D^-_s \pi^+$ decays are performed, reducing their uncertainty by about a factor of two with respect to previous world averages. Numerous $B^0_s$ decay branching fractions, measured at the LHCb experiment, are also updated using the new values of $f_s/f_d$ and branching fractions of normalisation channels. These results reduce a major source of systematic uncertainty in several searches for new physics performed through measurements of $B^0_s$ branching fractions.
Measurements of $ f_s/f_d$ sensitive observables as a function of the $ B $ -meson transverse momentum, $ p_{\mathrm{T}}$ , overlaid with the fit function. The scaling factors $r_{AF}$ and $r_{E}$ are defined in the text; the variable $\mathcal{R}$ is defined in Eq. 4. The vertical axes are zero-suppressed. The uncertainties on the data points are fully independent of each other; overall uncertainties for measurements in multiple $ p_{\mathrm{T}}$ intervals are propagated via scaling parameters, as described in the text. The band associated with the fit function shows the uncertainty on the post-fit function for each sample. |
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Efficiency correction versus effective lifetime hypothesis for the $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \phi$ branching fraction. The band shows the uncertainty on the correction due to the simulated sample size for a given effective lifetime. |
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Fragmentation fraction ratio $ f_s/f_d$ as a function of proton-proton centre-of-mass energy. |
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Measurements of $ f_s/f_d$ sensitive observables as a function of the $ B $ -meson transverse momentum, $ p_{\mathrm{T}}$ , overlaid with the fit function. A Tsallis-statistics inspired function is used in this plot as described in the text. The scaling factors $r_{AF}$ and $r_{E}$ are defined in the text; the variable $\mathcal{R}$ is defined in Eq. 4. The vertical axes are zero-suppressed. The uncertainties on the data points are fully independent of each other; overall uncertainties for measurements in multiple $ p_{\mathrm{T}}$ intervals are propagated through scaling parameters, as described in the text. The band associated with the fit function shows the uncertainty on the post-fit function for each sample. |
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Animated gif made out of all figures. |
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Five sets of measurements by the LHCb experiment combined in this paper and their sensitivity to fragmentation fractions and branching fractions. |
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External inputs used in the hadronic and semileptonic analyses updated with respect to previous publications. The value of $\mathcal{N}_E$ is updated using Ref. [7]. The values of CKM matrix elements ratio $|V_{us}| / |V_{ud}|$ and of the meson decay constants' ratio $f_K/f_\pi$ are the same as in Ref. [9]. |
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Observables and related parameters of the default fit. See text for a detailed explanation. |
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The branching fractions of $ B ^0$ and $ B ^+$ normalisation channel decays used to update previous measurements of $ B ^0_ s $ branching fractions, as reported in Ref. [7] for all but the $ B ^0 \rightarrow { J \mskip -3mu/\mskip -2mu\psi } K ^{*0} $ branching fraction, which is taken from the amplitude analysis in Ref [51], and corrected for the relative production fraction of $ B ^+$ and $ B ^0$ mesons at $ B $ Factories [50]. |
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Updated branching fractions of rare $ B ^0_ s $ decays. The uncertainties are statistical, systematic, due to $ f_s/f_d$ , and due to the normalisation branching fraction. The $ B ^0_ s \rightarrow \phi\mu ^+\mu ^- $ branching fractions in different $q^2$ intervals, where $q^2$ is defined as dimuon invariant mass squared in $\text{ Ge V /}c^2$ , are normalised with respect to $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \phi$ . Results with the $\star$ symbol have had their normalisation branching fraction updated as well. |
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Updated branching fractions of $ B ^0_ s $ decays with charmonia in the final state. The uncertainties are statistical, systematic, due to $ f_s/f_d$ , and due to the normalisation branching fraction. The second, third and fourth set of branching fractions are normalised to $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \phi$ , $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \eta^{(')}$, $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi } \pi ^+ \pi ^- $ , respectively, and their third uncertainty covers the full normalisation uncertainty. Results with the $\star$ symbol have had their normalisation branching fraction updated as well. |
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Updated branching fractions of $ B ^0_ s $ decays with a charmless final state. The uncertainties are statistical, systematic, due to $ f_s/f_d$ , and due to the normalisation branching fraction. The last two branching fractions are normalised with respect to $ B ^0_ s \rightarrow \phi\phi$ , and their third uncertainty covers the full normalisation uncertainty. Results with the $\star$ symbol have had their normalisation branching fraction updated as well. |
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Updated branching fractions of $ B ^0_ s $ decays to open-charm final states. The uncertainties are statistical, systematic, due to $ f_s/f_d$ , and due to the normalisation branching fraction. The $ B ^0_ s \rightarrow D ^{\mp}_ s K ^\pm $ , $ B ^0_ s \rightarrow D ^-_ s \pi ^+ \pi ^- \pi ^+ $ and $ B ^0_ s \rightarrow D ^-_ s K ^+ \pi ^- \pi ^+ , B ^0_ s \rightarrow D _{ s 1}(2536)^- \pi ^+ $ branching fractions are normalised with respect to $ B ^0_ s \rightarrow D ^-_ s \pi ^+ $ and $ B ^0_ s \rightarrow D ^-_ s \pi ^+ \pi ^- \pi ^+ $ , respectively, and their third uncertainty covers the full normalisation uncertainty. Results with the $\star$ symbol have had their normalisation branching fraction updated as well. |
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Output parameters of the default fit to the data. |
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Output parameters of the fit to the data without external theory constraints. |
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Output correlation matrix of the default fit versus $ p_{\mathrm{T}}$ . |
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Output correlation matrix of the fit versus $ p_{\mathrm{T}}$ without theory constraints. |
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Created on 26 April 2024.