Test of lepton flavor universality in B$^{\pm}$ $\to$ K$^{\pm}μ^+μ^-$ and B$^{\pm}$ $\to$ K$^{\pm}$e$^+$e$^-$ decays in proton-proton collisions at $\sqrt{s}$ = 13 TeV
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| Format: | Preprint |
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2024
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| author | CMS Collaboration |
| author_facet | CMS Collaboration |
| contents | A test of lepton flavor universality in B$^{\pm}$ $\to$ K$^{\pm}μ^+μ^-$ and B$^{\pm}$ $\to$ K$^{\pm}$e$^+$e$^-$ decays, as well as a measurement of differential and integrated branching fractions of a nonresonant B$^{\pm}$ $\to$ K$^{\pm}μ^+μ^-$ decay are presented. The analysis is made possible by a dedicated data set of proton-proton collisions at $\sqrt{s}$ = 13 TeV recorded in 2018, by the CMS experiment at the LHC, using a special high-rate data stream designed for collecting about 10 billion unbiased b hadron decays. The ratio of the branching fractions $\mathcal{B}$(B$^{\pm}$ $\to$ K$^{\pm}μ^+μ^-$) to $\mathcal{B}$(B$^{\pm}$ $\to$ K$^{\pm}$e$^+$e$^-$) is determined from the measured double ratio $R$(K) of these decays to the respective branching fractions of the B$^\pm$ $\to$ J/$ψ$K$^\pm$ with J/$ψ$ $\to$ $μ^+μ^-$ and e$^+$e$^-$ decays, which allow for significant cancellation of systematic uncertainties. The ratio $R$(K) is measured in the range 1.1 $\lt$ $q^2$ $\lt$ 6.0 GeV$^2$, where $q$ is the invariant mass of the lepton pair, and is found to be $R$(K) = 0.78 $^{+0.47}_{-0.23}$, in agreement with the standard model expectation $R$(K) $\approx$ 1. This measurement is limited by the statistical precision of the electron channel. The integrated branching fraction in the same $q^2$ range, $\mathcal{B}$(B$^{\pm}$ $\to$ K$^{\pm}μ^+μ^-$) = (12.42 $\pm$ 0.68) $\times$ 10$^{-8}$, is consistent with the present world-average value and has a comparable precision. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2401_07090 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Test of lepton flavor universality in B$^{\pm}$ $\to$ K$^{\pm}μ^+μ^-$ and B$^{\pm}$ $\to$ K$^{\pm}$e$^+$e$^-$ decays in proton-proton collisions at $\sqrt{s}$ = 13 TeV CMS Collaboration High Energy Physics - Experiment A test of lepton flavor universality in B$^{\pm}$ $\to$ K$^{\pm}μ^+μ^-$ and B$^{\pm}$ $\to$ K$^{\pm}$e$^+$e$^-$ decays, as well as a measurement of differential and integrated branching fractions of a nonresonant B$^{\pm}$ $\to$ K$^{\pm}μ^+μ^-$ decay are presented. The analysis is made possible by a dedicated data set of proton-proton collisions at $\sqrt{s}$ = 13 TeV recorded in 2018, by the CMS experiment at the LHC, using a special high-rate data stream designed for collecting about 10 billion unbiased b hadron decays. The ratio of the branching fractions $\mathcal{B}$(B$^{\pm}$ $\to$ K$^{\pm}μ^+μ^-$) to $\mathcal{B}$(B$^{\pm}$ $\to$ K$^{\pm}$e$^+$e$^-$) is determined from the measured double ratio $R$(K) of these decays to the respective branching fractions of the B$^\pm$ $\to$ J/$ψ$K$^\pm$ with J/$ψ$ $\to$ $μ^+μ^-$ and e$^+$e$^-$ decays, which allow for significant cancellation of systematic uncertainties. The ratio $R$(K) is measured in the range 1.1 $\lt$ $q^2$ $\lt$ 6.0 GeV$^2$, where $q$ is the invariant mass of the lepton pair, and is found to be $R$(K) = 0.78 $^{+0.47}_{-0.23}$, in agreement with the standard model expectation $R$(K) $\approx$ 1. This measurement is limited by the statistical precision of the electron channel. The integrated branching fraction in the same $q^2$ range, $\mathcal{B}$(B$^{\pm}$ $\to$ K$^{\pm}μ^+μ^-$) = (12.42 $\pm$ 0.68) $\times$ 10$^{-8}$, is consistent with the present world-average value and has a comparable precision. |
| title | Test of lepton flavor universality in B$^{\pm}$ $\to$ K$^{\pm}μ^+μ^-$ and B$^{\pm}$ $\to$ K$^{\pm}$e$^+$e$^-$ decays in proton-proton collisions at $\sqrt{s}$ = 13 TeV |
| topic | High Energy Physics - Experiment |
| url | https://arxiv.org/abs/2401.07090 |