test of lepton universality in beauty quark decays nature

Phys. Lett. J. Hiller, G. & Krger, F. More model-independent analysis of bs processes. Rev. provides an independent validation of the double-ratio analysis procedure and further tests the control of the efficiencies. The red line indicates the prediction from the SM. Background from decays with a photon converted into an e+e pair are also negligible due to the q2 selection. & Virto, J. Assessing lepton-flavour non-universality from BK* angular analyses. LHCb collaboration LHCb detector performance. Search for B+K++ at the BaBar experiment. The LHCbdetector at the LHC. High. Rev. The analysis uses beauty mesons produced in proton-proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 $\mathrm{fb}^{-1}$.. 3). An electron that emits a bremsstrahlung photon due to interactions with the material of the detector downstream of the dipole magnet results in the photon and electron depositing their energy in the same ECAL cells and therefore in a correct measurement of the original energy of the electron in the ECAL. 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. Physikalisches Institut, RWTH Aachen University, Aachen, Germany, J. M. Basels,L. Carus,S. Escher,A. Guth,J. Heuel,T. Kirn,S. Kretzschmar,C. Langenbruch,M. Materok,S. Nieswand,S. Schael,E. Smith&V. Zhukov, G. Bassi,F. Bedeschi,F. Lazzari,A. Lusiani,M. J. Morello,L. Pica,M. Rama,R. Ribatti,G. Tuci&J. Walsh, INFN Sezione di Cagliari, Monserrato, Italy, S. Belin,D. Brundu,S. Cadeddu,A. Cardini,A. Contu,F. Dettori,F. Dordei,M. Garau,A. Lai,A. Lampis,R. Litvinov,A. Loi,G. Manca,P. Muzzetto,R. Oldeman,B. Saitta&J. Extended Data Fig. Rev. 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. D 92, 072014 (2015). A. Monroy&J. High Energy Phys. Rev. 1, left). The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Instrum. Lett. Methods A 506, 250303 (2003). This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton-proton collision data collected with the LHCb detector at CERN's Large Hadron Collider. J. Uncertainties on the data points are statistical only and represent one standard deviation. Rev. Phys. . Today at the CERN seminar and at the Rencontres de Blois the LHCb Collaboration presented new tests of lepton universality, one of the basic principles of the Standard Model (SM) of particle physics. For the electron modes that dictate the RK precision, this requirement reduces the combinatorial background by approximately 99% while retaining 85% of the signal mode. On the standard model predictions for RK and \({R}_{{K}^{* }}\). Test of the universality of and lepton couplings in W-boson decays with the ATLAS detector, A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery, Search for charged-lepton-flavour violation in Z-boson decays with the ATLAS detector, Evidence for intrinsic charm quarks in the proton, Precise determination of the Differential branching fractions and isospin asymmetries of BK(*)+ decays. Aaij, R. et al. 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. Eur. Chat with our students. Correlations in the systematic uncertainties between different trigger categories and run periods are taken into account. EPJ Web Conf. Angular analysis of the B+K*++ decay. B-decay discrepancies after Moriond 2019. An example distribution, with rJ/ determined as a function of B+ momentum component transverse to the beam direction, pT, is shown in Fig. Anyone you share the following link with will be able to read this content: Sorry, a shareable link is not currently available for this article. Article Wehle, S. et al. 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. New tests of lepton universality show the same pattern as deviations 2010, 89 (2010). Davidson, N., Przedzinski, T. & Was, Z. High Energy Phys. 1. (Top) distributions of the reconstructed spectra of (left) the angle between the leptons, (+,), and (right) the minimum pT of the leptons for B+K++ and B+J/(+)K+ decays. Exp. In the fit for RK, these yields and the efficiencies are incorporated as Gaussian-constraint terms. Systematic uncertainties that affect the ratios of efficiencies influence the measured value of RK and are taken into account using constraints on the efficiency values. Kowalska, K., Kumar, D. & Sessolo, E. M. Implications for new physics in bs transitions after recent measurements by Belle and LHCb. 331, 032047 (2011). The SM is unable to explain cosmological observations of the dominance of matter over antimatter, the apparent dark matter content of the Universe, or the patterns seen in the interaction strengths of the particles. D 102, 055001 (2020). High Energy Phys. C 73, 2646 (2013). Zenodo https://doi.org/10.5281/zenodo.4587748. Individual groups or members have received support from ARC and ARDC (Australia); AvH Foundation (Germany); EPLANET, Marie Skodowska-Curie Actions and ERC (European Union); A*MIDEX, ANR, Labex P2IO and OCEVU, and Rgion Auvergne-Rhne-Alpes (France); Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP, Fundamental Research Funds for the Central Universities, and Sci. Phys. Test of lepton universality with beauty baryons, RpK Ser. Measurements of the angular distributions in the decays BK(*)+ at CDF. 12, 131 (2014). Marks,D. J. Unverzagt,U. Uwer,C. Wang,L. Witola&A. Zhelezov, Institute for High Energy Physics NRC Kurchatov Institute (IHEP NRC KI), Protvino, Russia, A. Artamonov,K. Belous,Y. Guz,S. Kholodenko,V. Obraztsov,S. Poslavskii,V. Romanovskiy,M. Shapkin,O. Stenyakin&O. Yushchenko, M. Artuso,B. Batsukh,A. Beiter,H. C. Bernstein,S. Blusk,S. Ely,Z. Li,X. Liang,R. Mountain,M. E. Olivares,T. T. H. Pham,M. Poliakova,I. Polyakov,M. S. Rudolph,J. D. Shupperd,T. Skwarnicki,S. Stone,A. Venkateswaran,M. Wilkinson,H. Wu,Y. Yao&X. Yuan, Yandex School of Data Analysis, Moscow, Russia, K. Arzymatov,V. Belavin,M. Borisyak,T. Gaintseva,A. Philippov,S. Popov,F. Ratnikov&A. Ustyuzhanin, Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France, E. Aslanides,J. Cerasoli,J. Cogan,D. Gerstel,R. Le Gac,O. Leroy,G. Mancinelli,C. Meaux,P. K. Resmi,A. Poluektov,R. I. Rabadan Trejo&D. Vom Bruch, Laboratoire Leprince-Ringuet, CNRS/IN2P3, Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau, France, B. Audurier,V. Balagura,F. Fleuret,F. A. Garcia Rosales&E. Maurice, Institute of Physics, Ecole Polytechnique Fdrale de Lausanne (EPFL), Lausanne, Switzerland, M. Bachmayer,A. D 95, 035029 (2017). To help overcome the challenge of modelling precisely the different electron and muon reconstruction efficiencies, the branching fractions of B+K++ decays are measured relative to those of B+J/K+ decays64. 2020, 40 (2020). C 80, 252 (2020). 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. For the non-resonant muon mode and for each of the three different trigger categories of the non-resonant electron mode, a single BDT classifier is trained for the 7 and 8TeV data, and an additional classifier is trained for the 13TeV data. The results are consistent between the different data-taking periods and with previous LHCbmeasurements37. 2 Nonresonant candidates invariant mass distributions. Slider with three articles shown per slide. Linear (top) and logarithmic (bottom) scales are shown. J. C76, 440 (2016). This is the most precise measurement of this quantity to date and, given the large (\({{{\mathcal{O}}}}(10 \%)\)) theoretical uncertainty on the predictions7,66, is consistent with the SM. In the measurement of the rJ/ ratio, the systematic uncertainty is dominated by the imperfect modelling of the B+ production kinematics and the modelling of selection requirements, which have a negligible impact on the RK measurement. Test of lepton universality in beauty-quark decays - Academia.edu This resolution scaling changes the migration of candidates into the q2 region of interest by less than 1%. New physics in bs+ confronts new data on lepton universality. The distribution of this ratio as a function of the angle between the leptons and the minimum pT of the leptons is shown in Extended Data Fig. Even though the non-resonant and resonant samples are mutually exclusive as a function of q2, there is significant overlap between them in the quantities on which the efficiency depends, such as the laboratory-frame momenta of the final-state particles or the opening angle between the two leptons. Hint of lepton flavour non-universality in B meson decays. Electroweak Penguin Decays at LHCb - ResearchGate A B+ meson, consisting of \(\overline{b}\) and uquarks, decays into a K+, containing \(\overline{s}\) and uquarks, and two charged leptons, +. Eur. The measurements are of processes in which a beauty meson transforms into a strange meson with . J. For each of the classifiers, a requirement is placed on the output variable to maximize the predicted significance of the non-resonant signal yield. ). At the LHC, proton-proton collisions produce copious numbers of bottom quarks and antiquarks, most of which become B mesons. PDF Test of lepton universality in beauty-quark decays - arXiv The rJ/ single ratio is used to perform a number of additional cross-checks. Horgan, R. R., Liu, Z., Meinel, S. & Wingate, M. Calculation of B0K*0+ and \({B}_{s}^{0}\to \ \ \phi {\mu }^{+}{\mu }^{-}\) observables using form factors from lattice QCD. Phys. 109, 101802 (2012). The Belle collaboration et al. Bharucha, A., Straub, D. M. & Zwicky, R. BV+ in the standard model from light-cone sum rules. 24, 01025 (2020). A multivariate algorithm is used for the identification of displaced vertices consistent with the decay of a B hadron77,78. Lett. The calibrated simulation is used subsequently to obtain the m(K++) mass shape and relative fractions of these background components. J. Instrum. Eur. J. Ser. 8 Candidate invariant mass distributions. J. Test of lepton universality in beauty-quark decays . Lett. & Wang, Y.-M. Charm-loop effect in B K(*)+ and B K*. J. Clemencic, M. et al. which does not benefit from the same cancellation of systematic effects. Lett. Angular analysis and differential branching fraction of the decay \({B}_{s}^{0}\to \phi {\mu }^{+}{\mu }^{-}\). Nature 546, 227 . Phys. Commun. The decay process involves the conversion of a beauty quark into a strange quark with the production of an electron and antielectron or a muon and antimuon. 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. reco. D 96 (2017) 095010 [ arXiv:1704.06659] [ INSPIRE ]. The y axis in each panel shows the number of candidates in an interval of the indicated width. The top row shows the fit to the muon modes and the subsequent rows the fits to the electron modes triggered by (second row) one of the electrons, (third row) the kaon and (last row) by other particles in the event. 2016, 47 (2016); erratum 2017, 142 (2017). These fractions are observed to agree well with those observed in resonant events selected from the data. Test of lepton universality in beauty-quark decays. CERN experiment found that beauty quarks not behaving in the way they Simulated events are weighted to correct for the imperfect modelling using control channels. Huschle, M. et al. The orange shaded area corresponds to B+K+e+e candidates with true q2 (\({q}_{{{{\rm{t}}}}rue}^{2}\)) outside the [1.1,6.0] GeV 2/c4 interval. The authors declare no competing interests. Test of lepton universality with B0K*0+ decays. Particle Physics (4th ed. 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. Measurement of the ratio of branching fractions \({{{\mathcal{B}}}}({\overline{B}}^{0}\to {D}^{* +}{\tau }^{-}{\overline{\nu }}_{\tau })/{{{\mathcal{B}}}}({\overline{B}}^{0}\to {D}^{* +}{\mu }^{-}{\overline{\nu }}_{\mu })\). Phys.) This is because a given set of values for the final-state particles momenta and angles in the B+ rest frame will result in a distribution of such values when transformed to the laboratory frame. Rev. Nucl. After the application of the selection requirements, the resonant and non-resonant decays are clearly visible in the mass distributions (Fig. Phys. Lett. Test of lepton universality in beauty-quark decays Angular analysis of the B0K*0+ decay using 3fb1 of integrated luminosity. Aaij, R. et al. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton-proton collision data collected with the LHCb detector at CERN's Large Hadron Collider. The likelihood is non-Gaussian in the region RK>0.95 due to the comparatively low yield of B+K+e+e events. In the electron case, a 40MeV c2 window around the D0 mass is used to reject candidates where the veto is applied without the bremsstrahlung recovery, that is, on the basis of only the measured track momenta. 331, 032023 (2011). 2019, 89 (2019). The value of RK is a fit parameter, which is related to the signal yields and efficiencies according to. Rev. Eur. Commun. D 89, 074014 (2014). D 68, 094016 (2003). Yields of the nonresonant and resonant decay modes obtained from the fits to the data. High Energy Phys. 2017, 112 (2017). The notation \({\pi }_{[\to {e}^{-}]}^{-}\) (\({e}_{[\to {\pi }^{-}]}^{-}\)) is used to denote an pion (electron) that is reconstructed as an electron (pion). 2017, 055 (2017). Other explanations of the data involve a variety of extensions to the SM, such as supersymmetry, extended Higgsboson sectors and models with extra dimensions. LHCb collaboration et al. We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (the Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland) and NERSC (United States). This uncertainty includes both statistical and systematic effects, where the latter dominate. 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