test of lepton universality in beauty quark decays nature

Rev. Phys. Correspondence to The effect on RK is at the 1% level. The BDT output is not strongly correlated with q2, and the same classifiers are used to select the respective resonant decays. Bremsstrahlung emission in the decay of particles is simulated using the PHotos software in the default configuration89, which is observed to agree with an independent quantum electrodynamics calculation at the level of 1% (ref. Methods A 462, 152155 (2001). 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. Test of lepton flavour universality in beauty-quark decays High Energy Phys. 82,83,84,85,86,87,88. An example distribution, with rJ/ determined as a function of B+ momentum component transverse to the beam direction, pT, is shown in Fig. Wills Physics Laboratory, University of Bristol, Bristol, UK, M. Adinolfi,S. Bhasin,P. Camargo Magalhaes,M. G. Chapman,R. Lane,S. Maddrell-Mander,L. R. Madhan Mohan,A. M. Marshall,P. Naik,D. P. OHanlon,K. Petridis,G. J. Pomery,J. H. Rademacker,J. J. Velthuis,R. Wang,B. D. C. Westhenry&M. Whitehead, Universit Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, MI, France, H. Afsharnia,Z. Ajaltouni,E. Cogneras,O. Deschamps,R. Lefvre,J. Maratas,S. Monteil,P. Perret,D. Popov,H. Sazak,L. Soares Lavra&V. Tisserand, C. A. Aidala,D. S. Fitzgerald,S. H. Lee,K. R. Mattioli,C. Nunez,J. D. Roth&D. M. Shangase, S. Aiola,J. Fu,P. Gandini,L. Henry,D. Marangotto,A. Merli,N. Neri,M. Petruzzo&E. Spadaro Norella, University of Cincinnati, Cincinnati, OH, USA, S. Akar,P. Ilten,B. Meadows,C. Pappenheimer,M. D. Sokoloff,M. Stahl&D. Vieira, Fakultt Physik, Technische Universitt Dortmund, Dortmund, Germany, J. Albrecht,A. Battig,M. Becker,M. S. Bieker,J. In this paper, a measurement of the RK ratio is presented based on protonproton collision data collected with the LHCb detector at the CERNs Large Hadron Collider (Methods). Savoie Mont Blanc, CNRS, IN2P3-LAPP, Annecy, France, M. Chefdeville,D. Decamp,A. G. Downes,Ph. Thank you for visiting nature.com. The lack of any dependence of the value of \({r}_{J/\psi }/ < {r}_{J/\psi } >\) as a function of B+ pT demonstrates control of the efficiencies. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. Hambrock, C., Hiller, G., Schacht, S. & Zwicky, R. BK* form factors from flavor data to QCD and back. Test of lepton universality in beauty-quark decays, arXiv:2103.1176 . The ratio of branching fractions, RH (refs. PhD thesis, Institute of Nuclear Physics, Krakow (1986). J. A boosted decision tree (BDT) algorithm79 with gradient boosting80 is used to reduce combinatorial background. Theor. Jger, S. & Martin Camalich, J. s High. Lepton universality is the idea that all three types of charged lepton particles - electrons, muons and taus - interact in the same way with other particles. Assuming that the deviations observed are genuine mis-modelling of the efficiencies, rather than statistical fluctuations, a total shift of RK at a level less than 0.001 would be expected due to these effects. 2010, 89 (2010). LHCb collaboration, Test of lepton universality in beauty-quark decays, Nature Phys. Test of lepton flavor universality by the measurement of the B0D*+ branching fraction using three-prong decays. 2006, 026 (2006). Following the procedure described in refs. The LHCb collaboration et al. 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. Article High. J. 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. 1. Pseudo-experiments are also used to assess the degree of bias originating from the fitting procedure. Physics - A Challenge to Lepton Universality Measurement of the ratio of branching fractions and difference in CP asymmetriesof the decays B+J/+ and B+J/K+. 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. Extended Data Fig. Novel Tests of Lepton Universality Boost Evidence for 'New Physics J. Measurement of the branching ratio of \({\overline{B}}^{0}\to {D}^{* +}{\tau }^{-}{\overline{\nu }}_{\tau }\) relative to \({\overline{B}}^{0}\to {D}^{* +}{\ell }^{-}{\overline{\nu }}_{\ell }\) decays with a semileptonic tagging method. In Proc. LHCb collaboration et al. Rev. J. C76, 440 (2016). Aaij, R. et al. Confirmation of any effect beyond the SM will clearly require independent evidence from a wide range of sources. Pion electronic decay and lepton universality - ResearchGate Aaltonen, T. et al. To take into account residual differences in the signal shape between data and simulation, an offset in the peak position and a scaling of the resolution are allowed to vary in the fits to the resonant modes. Conf. 3 Resonant candidates invariant mass distributions. 2015, 179 (2015). 2020, 40 (2020). 3,4,5,6,7), at the level of 0.10% (3.1 standard deviations), giving evidence for the violation of lepton universality in these decays. Rev. 2014, 133 (2014). & Wang, Y.-M. Charm-loop effect in B K(*)+ and B K*. J. The ratio between the branching fractions of these decays is therefore predicted with \({{{\mathcal{O}}}}(1 \%)\) precision3,4,5,6,7,8. B. Coelho,F. Desse,F. Machefert,E. M. Niel,P. Robbe,M. H. Schune&G. Wormser, L. Anderlini,A. Bizzeti,G. Graziani,S. Mariani,G. Passaleva&M. Veltri, M. Andreotti,W. Baldini,C. Bozzi,R. Calabrese,M. Fiorini,E. Franzoso,C. Giugliano,P. Griffith,M. Guarise,S. Kotriakhova,E. Luppi,A. Minotti,L. Minzoni,I. Neri,L. L. Pappalardo,B. Passalacqua,B. G. Siddi,I. Slazyk,L. Tomassetti&S. Vecchi, Physikalisches Institut, Ruprecht-Karls-Universitt Heidelberg, Heidelberg, Germany, F. Archilli,S. Bachmann,D. Berninghoff,M. Borsato,G. Frau,D. Gerick,J. P. Grabowski,P. A. Gnther,X. Han,S. Hansmann-Menzemer,J. Hu,R. Kopecna,B. Leverington,P. Li,H. Malygina,J. 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. 14, P11023 (2019). 2017, 055 (2017). 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. These differences arise due to the significant bremsstrahlung radiation emitted by the electrons and the different detector subsystems that are used to identify electron and muon candidates (Methods). The determination of the rJ/ ratio requires control of the relative selection efficiencies for the resonant electron and muon modes and does not therefore benefit from the cancellation of systematic effects in the double ratio used to measure RK. Commun. B. Zonneveld, Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania, L. Cojocariu,A. Ene,L. Giubega,A. Grecu,F. Maciuc,V. Placinta&M. Straticiuc, L. Congedo,M. De Serio,R. A. Fini,A. Palano,M. Pappagallo,A. Pastore&S. Simone, L. Congedo,M. De Serio,M. Pappagallo&S. Simone, Los Alamos National Laboratory (LANL), Los Alamos, NM, USA, J. Crkovsk,C. L. Da Silva,C. T. Dean,J. M. Durham,E. Epple&G. J. Kunde, Van Swinderen Institute, University of Groningen, Groningen, Netherlands, K. De Bruyn,C. J. G. Onderwater&M. van Veghel, Universiteit Maastricht, Maastricht, Netherlands, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Krakw, Poland, A. Dendek,M. Firlej,T. Fiutowski,M. Idzik,P. Kopciewicz,W. Krupa,O. Madejczyk,M. W. Majewski,J. Moron,A. Oblakowska-Mucha,B. Rachwal,J. Ryzka,K. Swientek&T. Szumlak, F. Dettori,C. Giugliano,G. Manca,R. Oldeman&B. Saitta, Eotvos Lorand University, Budapest, Hungary, Institute for Nuclear Research of the National Academy of Sciences (KINR), Kyiv, Ukraine, V. Dobishuk,S. Koliiev,I. Kostiuk,O. Kot&V. Pugatch, School of Physics, University College Dublin, Dublin, Ireland, A. M. Donohoe,L. Mcconnell,R. McNulty,N. V. Raab&C. B. D 97, 012004 (2018). Comput. The vertical dashed line indicates the SM prediction. 199, 86101 (2016). Hiller, G. & Krger, F. More model-independent analysis of bs processes. Whenever a process is specified in this paper, the inclusion of the charge-conjugate mode is implied. 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). 5, together with the spectra expected for the resonant and non-resonant decays. 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. Sjstrand, T., Mrenna, S. & Skands, P. A brief introduction to PYTHIA 8.1. Isidori, G., Nabeebaccus, S. & Zwicky, R. QED corrections in \(\overline{B}\to \overline{K}{{{{\rm{\ell }}}}}^{+}{{{{\rm{\ell }}}}}^{-}\) at the double-differential level. Test of lepton flavor universality and search for lepton flavor violation in BK decays. 115, 111803 (2015); erratum 115, 159901 (2015). 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 collider accelerates two counter-rotating beams of protons, guided by superconducting magnets located around a 27km circular tunnel, and brings them into collision at four interaction points that house large detectors. Sifting through proton . Martnez Santos, D. & Dupertuis, F. Mass distributions marginalized over per-event errors. Resolution effects similarly motivate the choice of non-resonant q2 regions, with a lower limit that excludes contributions from -meson decays and an upper limit that reduces the tail from B+J/(e+e)K+ decays. 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.

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