test of lepton universality in beauty quark decays naturetest of lepton universality in beauty quark decays nature

Aaij, R. et al. In particular, in the RK ratio, the denominator is affected by larger statistical uncertainties than the numerator, owing to the larger number of non-resonant muonic signal candidates. The theory predicts that the different charged leptons, the electron, muon and tau, have . Other experiments should also be able to determine RH ratios, with the Belle II experiment in particular expected to have competitive sensitivity72. Serra, N., Silva Coutinho, R. & van Dyk, D. Measuring the breaking of lepton flavor universality in BK*+. Compared with the previous LHCb RK result11, the experimental method is essentially identical but the analysis uses an additional 4fb1 of data collected in 2017 and 2018. Search for the decays \({B}_{s}^{0}\to {\tau }^{+}{\tau }^{-}\) and B0+. To accommodate possible lepton universality violation in these partially reconstructed processes, which are underpinned by the same \(\overline{b}\to \overline{s}\) quark-level transitions as those of interest, the overall yield of such decays is left to vary freely in the fit. Nucl. For the electron modes, in addition to combinatorial background, other specific background decays contribute significantly in the signal region. Observables studied include rare meson decays, flavor oscillations of neutral mesons, rare lepton decays, and dipole moments. 8 Candidate invariant mass distributions. The y axis in each panel shows the number of candidates in an interval of the indicated width. {6\ }_{-\ 1.4}^{+\ 1.5}\ \pm 1.3)\times 1{0}^{-9}\ {c}^{4}\,{{{{\rm{GeV}}}}}^{-2}\ .\end{array}$$, \(\overline{b}\to \overline{s}{\ell }^{+}{\ell }^{-}\), \(\overline{b}\to \overline{s}{\tau }^{+}{\tau }^{-}\), \(B\to {H}_{c}(\to {K}^{+}{\ell }^{-}{\overline{\nu }}_{\ell }X){\ell }^{+}{\nu }_{\ell }Y\), $$\begin{array}{rcl}{R}_{K}&=&\frac{N({B}^{+}\to {K}^{+}{\mu }^{+}{\mu }^{-})}{\varepsilon ({B}^{+}\to {K}^{+}{\mu }^{+}{\mu }^{-})}\cdot \frac{\varepsilon ({B}^{+}\to {K}^{+}{e}^{+}{e}^{-})}{N({B}^{+}\to {K}^{+}{e}^{+}{e}^{-})}\\ &&\times \frac{\varepsilon ({B}^{+}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){K}^{+})}{N({B}^{+}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){K}^{+})}\cdot \frac{N({B}^{+}\to J/\psi (\to {e}^{+}{e}^{-}){K}^{+})}{\varepsilon ({B}^{+}\to J/\psi (\to {e}^{+}{e}^{-}){K}^{+})}\ ,\end{array}$$, \(\overline{B}\to \overline{K}{{{{\rm{\ell }}}}}^{+}{{{{\rm{\ell }}}}}^{-}\), \({\Lambda }_{b}^{0}\to p{K}^{-}{\ell }^{+}{\ell }^{-}\), \({B}_{d}^{0}\to {K}^{* }{\mu }^{+}{\mu }^{-}\), \({B}_{s}^{0}\to \phi {\mu }^{+}{\mu }^{-}\), \({\Lambda }_{b}^{0}\to \Lambda {\mu }^{+}{\mu }^{-}\), \({B}_{s}^{0}\to \ \ \phi {\mu }^{+}{\mu }^{-}\), \(\overline{B}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }\), \({{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\tau }^{+}{\nu }_{\tau })/{{{\mathcal{B}}}}{{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu })\), \({\overline{B}}^{0}\to {D}^{* +}{\tau }^{-}{\overline{\nu }}_{\tau }\), \({\overline{B}}^{0}\to {D}^{* +}{\ell }^{-}{\overline{\nu }}_{\ell }\), \({{{\mathcal{B}}}}({\overline{B}}^{0}\to {D}^{* +}{\tau }^{-}{\overline{\nu }}_{\tau })/{{{\mathcal{B}}}}({\overline{B}}^{0}\to {D}^{* +}{\mu }^{-}{\overline{\nu }}_{\mu })\), \({B}^{0}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }\), \(\overline{B}\to \ \ {D}^{(*)}{\ell }^{-}{\overline{\nu }}_{\ell }\), \(\overline{B}\to {D}^{* }{\tau }^{-}{\overline{\nu }}_{\tau }\), \({{{\mathcal{B}}}}[\psi (3686)\to \ \ {\pi }^{+}{\pi }^{-}J/\psi ]\), \({{{\mathcal{B}}}}[J/\psi \to \ \ {\ell }^{+}{\ell }^{-}]\), \({B}_{s}^{0}\to {\tau }^{+}{\tau }^{-}\), https://doi.org/10.1038/s41567-021-01478-8. J. 12, 104 (2020). This estimate takes into account the spectrum of the relevant variables in the non-resonant decay modes of interest and is compatible with the estimated systematic uncertainties on RK. & Virto, J. Assessing lepton-flavour non-universality from BK* angular analyses. Phys. Lett. Energy Phys. Hirose, S. et al. Such background is reduced to a negligible level by particle identification criteria. To take into account the correlation between the selection efficiencies, the m(K+e+e) and m(K++) distributions of non-resonant candidates in each of the different trigger categories and data-taking periods are fitted simultaneously, with a common value of RK. The latter also tend to accumulate around specific values of m(K++). The selection requirements applied to the non-resonant and resonant decays are otherwise identical. 1, left). Descotes-Genon, S., Hofer, L., Matias, J. Rev. High. Performance of the ATLAS level-1 topological trigger in run 2. For each of the classifiers, a requirement is placed on the output variable to maximize the predicted significance of the non-resonant signal yield. $$\overline B_{\mathrm{s}}^0$$ Similar considerations apply to decays with other B hadrons, BH+ and BHe+e, where B= B+, B0, \({B}_{s}^{0}\) or \({\Lambda }_{b}^{0}\), and H can be, for example, an excited kaon, K*0, or a combination of particles such as a proton and charged kaon, pK. In addition, if the simulation is correctly calibrated, the measured rJ/ value will not depend on any variable. & Rusov, A. V. BsK and B(s)(K)+ decays at large recoil and CKM matrix elements. Electroweak Penguin Decays at LHCb - ResearchGate Other sources of systematic uncertainty, such as the calibration of B+ production kinematics, the trigger calibration and the determination of the particle identification efficiencies, contribute at the few-permille or permille level, depending strongly on the data-taking period and the trigger category. Extended Data Fig. The distributions are all normalised to unity. The B+ production kinematics are corrected using B+J/(+)K+ events. Test of lepton universality in beauty-quark decays - ResearchGate Long-distance effects in BK* from analyticity. Lett. Uncertainties on the data points are statistical only and represent one standard deviation. The experiment is designed to study decays of particles containing a beauty quark, a fundamental particle that has roughly four times the mass of the proton. However, the strong force does not couple directly to leptons, hence its effect on the B+K++ and B+K+e+e decays is identical. Capdevila, B., Descotes-Genon, S., Matias, J. Google Scholar. Jger, S. and Martin, J. Pion electronic decay and lepton universality License CC BY 4.0 Authors: Dinko Pocanic Abstract In common with a number of simple processes involving elementary particles, charged pion decays. (Bottom) the single ratio rJ/ relative to its average value \(< {r}_{J/\psi } >\) as a function of these variables. The dominant such background for the non-resonant and resonant modes comes from partially reconstructed B(0,+)K+(,0)e+e and B(0,+)J/(e+e)K+(,0) decays, respectively, where the pion is not included in the B+ candidate. Test of lepton universality in beauty-quark decays LHCb Collaboration Roel Aaij( NIKHEF, Amsterdam Show All(961) Mar 22, 2021 25 pages Published in: Nature Phys.18(2022)3,277-282 Published: Mar 15, 2022 e-Print: 2103.11769[hep-ex] DOI: 10.1038/s41567-021-01478-8 Report number: LHCb-PAPER-2021-004, CERN-EP-2021-042 Experiments: CERN-LHC-LHCb Phys. 1, right) and could have non-universal interactions, hence giving branching fractions of B+K++ decays with different leptons that differ from the SM predictions. Hiller, G. & Krger, F. More model-independent analysis of bs processes. Extended Data Table 1 Nonresonant and resonant mode. Internet Explorer). J. C76, 440 (2016). A. Bertolin. Lepton-flavor-dependent angular analysis of BK*+. Test of lepton universality in beauty-quark decays Energy Phys. Hunter,T. P. Jones,M. Kenzie,M. Kreps,T. Latham,O. Lupton,E. Millard,A. G. Morris,B. Pagare,M. Ramos Pernas,N. Sahoo&M. Vesterinen, Centro Brasileiro de Pesquisas Fsicas (CBPF), Rio de Janeiro, Brazil, J. Baptista Leite,I. Bediaga,M. Cruz Torres,J. M. De Miranda,A. C. dos Reis,A. Gomes,A. Massafferri,G. Punzi&D. Torres Machado, W. Barter,M. Birch,M. J. Bradley,A. Golutvin,M. Hecker,F. Kress,T. Lin,M. McCann,R. D. Moise,R. Newcombe,M. Patel,M. Smith&D. Websdale, M. Bartolini,R. Cardinale,F. Fontanelli,A. Petrolini&A. Sergi, National University of Science and Technology MISIS, Moscow, Russia, F. Baryshnikov,S. Didenko,A. Golutvin,S. Gromov,A. Ishteev,A. Kondybayeva,S. Legotin,N. Polukhina,D. Saranin,I. Shchemerov,E. Shmanin,O. Steinkamp,D. Strekalina,E. Trifonova,E. Ursov&E. van Herwijnen, I. 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Kudryavtsev,T. Maltsev,L. Shekhtman&V. Vorobyev, University of Maryland, College Park, MD, USA, S. Braun,A. D. Fernez,M. Franco Sevilla,P. M. Hamilton,A. Jawahery,W. Parker,Y. J. Phys. reco. In the remainder of this paper, the notation B+K++ is used to denote only decays with 1.1Flavor probes of axion-like particles | SpringerLink High. Lett. The signal mass shapes of the electron modes are described with the sum of three distributions, which model whether the ECAL energy deposit from a bremsstrahlung photon was added to both, either or neither of the e candidates. Rev. oscillation frequency, Probing CP symmetry and weak phases with entangled double-strange baryons, Polarization and entanglement in baryonantibaryon pair production in electronpositron annihilation, The Higgs boson implications and prospects for future discoveries, http://opendata.cern.ch/record/410/files/LHCb-Data-Policy.pdf, https://www.hepdata.net/record/ins1852846?version=1. A consistent model-independent interpretation of all these data is possible via a modification of the \(\overline{b}\to \overline{s}\) coupling strength48,49,50,51,52,53,54. The Standard Model predicts that this occurs via electroweak bosons and the W + and Z 0 particles. Lett. This is the most precise measurement of this ratio to date and is compatible with the SM prediction with a P value of 0.10%. 118, 251802 (2017). PDF Test of lepton universality in beauty-quark decays - DiVA portal Uncertainties on the data points are statistical only and represent one standard deviation, calculated assuming Poisson-distributed entries. Uncertainties on the data points are statistical only and represent one standard deviation, calculated assuming Poisson-distributed entries. D 103, 015030 (2021). Phys. The yields observed in these four decay modes and the ratios of efficiencies determined from simulated events then enable an RK measurement with statistically dominated uncertainties. J. D 102, 055001 (2020). High. Lees, J. P. et al. So far, LHCb has collected 260 billion bottom-quark antiquark pairs in experimental runs using protons with 7 and 8 tera-electron-volt (TeV) center-of-mass energies. Left: the SM contribution involves the electroweak bosons ,W+ and Z0, and the up-type quarks , \(\bar{c}\) and \(\bar{t}\). Differential branching fractions and isospin asymmetries of BK(*)+ decays. 664, 082025 (2015). Rev. Eur. 2010, 89 (2010). MathSciNet Khodjamirian, A., Mannel, T. & Wang, Y.-M. BK+ decay at large hadronic recoil. Uncertainties on the data points are statistical only and represent one standard deviation. Rev. The B+J/(+)K+ events selected from the data have also been used to demonstrate control of the electron track reconstruction efficiency at the percent level90. Test of lepton universality in beauty-quark decays - CERN Document Server 126, 161801 (2021). Geant4 developments and applications, IEEE Trans. Aaij, R. et al. provides an independent validation of the double-ratio analysis procedure and further tests the control of the efficiencies. Article Phys. Different types of charged particles are distinguished using information from two ring-imaging Cherenkov detectors, a calorimeter and a muon system76. PDF Beauty quarks test lepton universality - cds.cern.ch 0 Lees, J. P. et al. Likhomanenko, T. et al. The raw data in all of the figures of this paper, and additional supplementary material, can be downloaded from https://cds.cern.ch/record/2758740, where no access codes are required. Theor. Agostinelli, S. et al. Tension with the SM is also seen in the combination of several ratios that test lepton universality in \(\overline{b}\to \overline{c}{\ell }^{+}{\nu }_{\ell }\) transitions55,56,57,58,59,60,61,62,63. B Test of lepton universality using B+K++ decays. Phys. The value of rJ/ is measured to be 0.9810.020. Such decays also exhibit some tension with the SM predictions but the extent of residual QCD effects is still the subject of debate3,21,39,40,41,42,43,44,45,46,47. ). Particle physicists have therefore been searching for new physics, that is, new particles and interactions that can explain the SMs shortcomings. Rev. The fit projections are superimposed, with dotted lines describing the signal contribution and solid areas representing each of the background components described in the text and listed in the legend. 11, and only the main analysis steps are reviewed here. Kou, E. et al. Theor. All contributing authors, as listed at the end of the manuscript, have contributed to the publication, being variously involved in the design and construction of the detector, writing software, calibrating sub-systems, operating the detector, acquiring data and analysing the processed data. Classification and Regression Trees (Wadsworth, 1984). Preprint at https://arxiv.org/abs/1406.0566 (2014). Aaij, R. et al. 2017, 36 (2017). Kowalska, K., Kumar, D. & Sessolo, E. M. Implications for new physics in bs transitions after recent measurements by Belle and LHCb. Test of lepton universality in beauty-quark decays . The results supersede those of the previous LHCb analysis. Background from other exclusive B-hadron decays requires at least two particles to be misidentified. Conversely, the non-resonant distributions show the projections from the simultaneous fit across data-taking periods and trigger categories that is used to obtain RK. Energy Phys. Update of lepton universality test measurement RK - CERN 82,83,84,85,86,87,88. High Energy Phys. Phys. These uncertainties are propagated to an uncertainty on RK using predictions from the FLAVIO software package7 but give rise to a negligible effect. J. Such a modification can be realized in new physics models with an additional heavy neutral boson or with leptoquarks. Phys. 2). The simulated data used in this analysis are produced using the software described in refs. Conf. J. Test of lepton universality in beauty-quark decays Test of lepton universality in beauty-quark decays - ResearchGate Lett. Given the scale of the corrections required, comparison of rJ/ with unity is a stringent cross-check of the experimental procedure. These include the decays B+K++, and misreconstructed B+J/(+)K+ and B+(2S)(+)K+ decays. Explore our virtual experience 122, 191801 (2019). Search for lepton-universality violation in B+K++ decays. 331, 032023 (2011). 24, 01025 (2020). 125, 011802 (2020). The k-folding technique is used in the training and testing81. Aebischer, J. et al. Sci. (Right, with linear y-scale) the mass is computed only from the track information. 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An unbinned extended maximum-likelihood fit is made to the m(K+e+e) and m(K++) distributions of non-resonant candidates. Publishers note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. The fitted yields for the resonant and non-resonant decays are given in Extended Data Table 2. Test of lepton universality in beauty-quark decays LHCb collaboration Nature Physics 18 , 277-282 ( 2022) Cite this article 8068 Accesses 76 Citations 29 Altmetric Metrics Abstract. The double ratio of branching fractions, R(2S), defined by.