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| CMS-BPH-18-004 ; CERN-EP-2021-271 | ||
| Observation of ${\mathrm{B}^{0} \to\psi(\text{2S}) {\mathrm{K^0_S}}\pi^{+}\pi^{-}}$ and ${{\mathrm{B^{0}_{s}}} \to\psi(\text{2S}) {\mathrm{K^0_S}} }$ decays | ||
| CMS Collaboration | ||
| 22 January 2022 | ||
| Eur. Phys. J. C 82 (2022) 499 | ||
| Abstract: Using a data sample of $\sqrt{s} = $ 13 TeV proton-proton collisions collected by the CMS experiment at the LHC in 2017 and 2018 with an integrated luminosity of 103 fb$^{-1}$, the ${{\mathrm{B^{0}_{s}}} \to\psi(\text{2S}) {\mathrm{K^0_S}} }$ and ${\mathrm{B}^{0} \to\psi(\text{2S}) {\mathrm{K^0_S}}\pi^{+}\pi^{-}}$ decays are observed with significances exceeding 5 standard deviations. The resulting branching fraction ratios, measured for the first time, correspond to ${\mathcal{B}} ({{\mathrm{B^{0}_{s}}} \to\psi(\text{2S}) {\mathrm{K^0_S}} } )/{\mathcal{B}} ({\mathrm{B}^{0} \to\psi(\text{2S}) {\mathrm{K^0_S}} } ) = $ (3.33 $\pm$ 0.69 (stat) $\pm$ 0.11 (syst) $\pm$ 0.34 (${f_\mathrm{s}/f_\mathrm{d}} $)) $\times$ 10$^{-2}$ and ${\mathcal{B}} ({\mathrm{B}^{0} \to\psi(\text{2S}) {\mathrm{K^0_S}}\pi^{+}\pi^{-}})/{\mathcal{B}} ({\mathrm{B}^{0} \to\psi(\text{2S}) {\mathrm{K^0_S}} } ) = $ 0.480 $\pm$ 0.013 (stat) $\pm$ 0.032 (syst), where the last uncertainty in the first ratio is related to the uncertainty in the ratio of production cross sections of ${\mathrm{B^{0}_{s}}} $ and ${\mathrm{B}^{0}} $ mesons, ${f_\mathrm{s}/f_\mathrm{d}} $. | ||
| Links: e-print arXiv:2201.09131 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Measured invariant mass distributions of $ \psi(\text{2S}) {\mathrm{K^0_S}} $ (left) and $ \psi(\text{2S}) {\mathrm{K^0_S}} {{\pi^{+}} {\pi^{-}}} $ (right) candidates. The overlaid results from the fit are described in the text. |
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Figure 1-a:
Measured invariant mass distribution of $ \psi(\text{2S}) {\mathrm{K^0_S}} $ candidates. The overlaid results from the fit are described in the text. |
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Figure 1-b:
Measured invariant mass distribution of $ \psi(\text{2S}) {\mathrm{K^0_S}} {{\pi^{+}} {\pi^{-}}} $ candidates. The overlaid results from the fit are described in the text. |
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Figure 2:
Distributions of 2-body intermediate invariant masses from the ${\mathrm{B}^{0} \to \psi(\text{2S}) {\mathrm{K^0_S}} {\pi^{+}} {\pi^{-}}}$ decay. The data distributions (black dots) are background subtracted. Overlaid are the predictions of phase space simulations (red triangles), as well as the predictions after applying the reweighting procedure described in Section 7 (grey squares). |
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Figure 2-a:
Distribution of the $\pi^{+}\pi^{-}$ invariant mass from the ${\mathrm{B}^{0} \to \psi(\text{2S}) {\mathrm{K^0_S}} {\pi^{+}} {\pi^{-}}}$ decay. The data distribution (black dots) is background subtracted. Overlaid are the predictions of phase space simulations (red triangles), as well as the predictions after applying the reweighting procedure described in Section 7 (grey squares). |
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Figure 2-b:
Distribution of the $\psi(\text{2S}\mathrm{K^0_S}$ invariant mass from the ${\mathrm{B}^{0} \to \psi(\text{2S}) {\mathrm{K^0_S}} {\pi^{+}} {\pi^{-}}}$ decay. The data distribution (black dots) is background subtracted. Overlaid are the predictions of phase space simulations (red triangles), as well as the predictions after applying the reweighting procedure described in Section 7 (grey squares). |
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Figure 2-c:
Distribution of the $\psi(\text{2S}\pi^{-}$ invariant mass from the ${\mathrm{B}^{0} \to \psi(\text{2S}) {\mathrm{K^0_S}} {\pi^{+}} {\pi^{-}}}$ decay. The data distribution (black dots) is background subtracted. Overlaid are the predictions of phase space simulations (red triangles), as well as the predictions after applying the reweighting procedure described in Section 7 (grey squares). |
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Figure 2-d:
Distribution of the $\mathrm{K^0_S}\pi^{-}$ invariant mass from the ${\mathrm{B}^{0} \to \psi(\text{2S}) {\mathrm{K^0_S}} {\pi^{+}} {\pi^{-}}}$ decay. The data distribution (black dots) is background subtracted. Overlaid are the predictions of phase space simulations (red triangles), as well as the predictions after applying the reweighting procedure described in Section 7 (grey squares). |
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Figure 2-e:
Distribution of the $\psi(\text{2S}\pi^{+}$ invariant mass from the ${\mathrm{B}^{0} \to \psi(\text{2S}) {\mathrm{K^0_S}} {\pi^{+}} {\pi^{-}}}$ decay. The data distribution (black dots) is background subtracted. Overlaid are the predictions of phase space simulations (red triangles), as well as the predictions after applying the reweighting procedure described in Section 7 (grey squares). |
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Figure 2-f:
Distribution of the $\mathrm{K^0_S}\pi^{+}$ invariant mass from the ${\mathrm{B}^{0} \to \psi(\text{2S}) {\mathrm{K^0_S}} {\pi^{+}} {\pi^{-}}}$ decay. The data distribution (black dots) is background subtracted. Overlaid are the predictions of phase space simulations (red triangles), as well as the predictions after applying the reweighting procedure described in Section 7 (grey squares). |
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Figure 3:
Distributions of 3-body intermediate invariant masses from the ${\mathrm{B}^{0} \to \psi(\text{2S}) {\mathrm{K^0_S}} {\pi^{+}} {\pi^{-}}}$ decay. Data distributions (black dots) are background subtracted. Overlaid are the predictions of phase space simulations (red triangles), as well as the predictions after applying the reweighting procedure described in Section 7 (grey squares). |
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Figure 3-a:
Distribution of the $\psi(\text{2S})\pi^{+}\pi^{-}$ invariant mass from the ${\mathrm{B}^{0} \to \psi(\text{2S}) {\mathrm{K^0_S}} {\pi^{+}} {\pi^{-}}}$ decay. The data distribution (black dots) is background subtracted. Overlaid are the predictions of phase space simulations (red triangles), as well as the predictions after applying the reweighting procedure described in Section 7 (grey squares). |
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Figure 3-b:
Distribution of the ${\mathrm{K^0_S}}\pi^{+}\pi^{-}$ invariant mass from the ${\mathrm{B}^{0} \to \psi(\text{2S}) {\mathrm{K^0_S}} {\pi^{+}} {\pi^{-}}}$ decay. The data distribution (black dots) is background subtracted. Overlaid are the predictions of phase space simulations (red triangles), as well as the predictions after applying the reweighting procedure described in Section 7 (grey squares). |
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Figure 3-c:
Distribution of the $\psi(\text{2S}){\mathrm{K^0_S}}\pi^{+}$ invariant mass from the ${\mathrm{B}^{0} \to \psi(\text{2S}) {\mathrm{K^0_S}} {\pi^{+}} {\pi^{-}}}$ decay. The data distribution (black dots) is background subtracted. Overlaid are the predictions of phase space simulations (red triangles), as well as the predictions after applying the reweighting procedure described in Section 7 (grey squares). |
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Figure 3-d:
Distribution of the $\psi(\text{2S}){\mathrm{K^0_S}}\pi^{-}$ invariant mass from the ${\mathrm{B}^{0} \to \psi(\text{2S}) {\mathrm{K^0_S}} {\pi^{+}} {\pi^{-}}}$ decay. The data distribution (black dots) is background subtracted. Overlaid are the predictions of phase space simulations (red triangles), as well as the predictions after applying the reweighting procedure described in Section 7 (grey squares). |
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Figure 4:
Background-subtracted $ {p_{\mathrm {T}}} ({\mathrm{B}^{0}})$ distribution in data for the ${\mathrm{B}^{0} \to \psi(\text{2S}) {\mathrm{K^0_S}}}$ signal. The last bin includes the overflow. |
| Tables | |
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Table 1:
Systematic uncertainties (in %) of the measured branching fraction ratios. |
| Summary |
| The ${{\mathrm{B^{0}_{s}}} \to\psi(\text{2S}) {\mathrm{K^0_S}} }$ and ${\mathrm{B}^{0} \to\psi(\text{2S}) {\mathrm{K^0_S}}\pi^{+}\pi^{-}}$ decays are observed using proton-proton collision data collected by the CMS experiment at 13 TeV with an integrated luminosity of 103 fb$^{-1}$. Their branching fractions are measured with respect to the ${\mathrm{B}^{0} \to\psi(\text{2S}) {\mathrm{K^0_S}} }$ decay to be ${\mathcal{B}} ({{\mathrm{B^{0}_{s}}} \to\psi(\text{2S}) {\mathrm{K^0_S}} } )/{\mathcal{B}} ({\mathrm{B}^{0} \to\psi(\text{2S}) {\mathrm{K^0_S}} } ) = $ (3.33 $\pm$ 0.69 (stat) $\pm$ 0.11 (syst) $\pm$ 0.34 (${f_\mathrm{s}/f_\mathrm{d}} $)) $\times$ 10$^{-2}$, and ${\mathcal{B}} ({\mathrm{B}^{0} \to\psi(\text{2S}) {\mathrm{K^0_S}}\pi^{+}\pi^{-}})/{\mathcal{B}} ({\mathrm{B}^{0} \to\psi(\text{2S}) {\mathrm{K^0_S}} } )= $ 0.480 $\pm$ 0.013 (stat) $\pm$ 0.032 (syst), where the last uncertainty in the first ratio corresponds to the uncertainty in the ratio of production cross sections of ${\mathrm{B^{0}_{s}}}$ and ${\mathrm{B}^{0}}$ mesons. The 2- and 3-body invariant mass distributions of the ${\mathrm{B}^{0} \to\psi(\text{2S}) {\mathrm{K^0_S}}\pi^{+}\pi^{-}}$ decay products do not show significant exotic narrow structures in addition to the known light meson resonances. Further studies with more data will be needed to investigate more precisely the internal dynamics of the ${\mathrm{B}^{0} \to\psi(\text{2S}) {\mathrm{K^0_S}}\pi^{+}\pi^{-}}$ decay, and to perform CP asymmetry measurements in the two observed decays in the future. |
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