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. 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 $\mathrm{fb}^{-1}$.. 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. High Energy Phys. Conf. Sign up for the Nature Briefing newsletter what matters in science, free to your inbox daily. For each of the classifiers, a requirement is placed on the output variable to maximize the predicted significance of the non-resonant signal yield. The authors declare no competing interests. D 94, 072007 (2016). Lett. Geant4 developments and applications, IEEE Trans. The proportion of signal candidates that migrate in and out of the q2 region of interest is on the order of 10%. LHCb data used in this analysis will be released according to the LHCb external data access policy, which can be downloaded from http://opendata.cern.ch/record/410/files/LHCb-Data-Policy.pdf. He,W. Huang,H. Liu,X. Lyu,R. Ma,W. Qian,J. Qin,Z. Xiang,J. Xu,Q. Xu,Z. Xu,S. Yang,Y. Yang,Y. Zheng,X. Zhou,Y. Zhou&Z. Zhu, L. Capriotti,A. Carbone,A. Falabella,F. Ferrari,D. Galli,S. Maccolini,D. Manuzzi,U. Marconi,C. Patrignani,S. Perazzini,M. Soares,V. Vagnoni,G. Valenti&S. Zucchelli, L. Capriotti,A. Carbone,F. Ferrari,D. Galli,S. Maccolini,D. Manuzzi,C. Patrignani&S. Zucchelli, INFN Sezione di Roma Tor Vergata, Roma, Italy, Institute Of High Energy Physics (IHEP), Beijing, China, I. Carli,S. Chen,Y. Li,Y. Li,S. Liu,Y. Lu,L. Ma,M. Tobin,J. Wang&Q. Zou, Univ. 120, 121801 (2018). Nucl. Eur. Lett. The B+K++ and B+J/(+)K+ candidates must be triggered by one of the muons, whereas B+K+e+e and B+J/(e+e)K+ candidates must be triggered in one of three ways: by either one of the electrons, by the kaon from the B+ decay or by other particles in the event that are not decay products of the B+ candidate. 1 (left). Similarly, computations of the rJ/ ratio in bins of two kinematic variables also do not show any trend and are consistent with the systematic uncertainties assigned on the RK measurement. C 82, 7 (2022). Rev. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction. {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. Distribution of the invariant mass m(K++) for nonresonant candidates in the (left) sample previously analysed11 and (right) the new data sample. 1, left). The Standard Model of particle physics predicts that particles called beauty quarks, which are measured in the LHCb experiment, should decay into either muons or electrons in equal measure. In the resonant-mode distributions, some fit components are too small to be visible. 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. Bobeth, C., Chrzaszcz, M., van Dyk, D. & Virto, J. ISSN 1745-2481 (online) C 80, 252 (2020). High Energy Phys. D 96, 093006 (2017). To avoid unconscious bias, the analysis procedure was developed and the cross-checks described below performed before the result for RK was examined. LHCb collaboration et al. The resonant yields are determined from separate fits to mJ/(K++). Predictions for lepton flavor universality violation in rare B decays in models with gauged LL. Extended Data Fig. The ATLAS and CMS experiments may also be able to contribute73,74. The rJ/ single ratio is used to perform a number of additional cross-checks. The particles are required to originate from a common vertex, with good vertex-fit quality, that is displaced significantly from all of the PVs in the event. Aaij, R. et al. Rev. Evidence for an excess of \(\overline{B}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }\) decays. LHCb explores the beauty of lepton universality - phys.org A precision measurement of the mass of the top quark | Nature The corresponding significance in terms of standard deviations is computed using the inverse Gaussian cumulative distribution function for a one-sided conversion. Uncertainties on the data points are statistical only and represent one standard deviation, calculated assuming Poisson-distributed entries. Lees, J. P. et al. Confirmation of any effect beyond the SM will clearly require independent evidence from a wide range of sources. 08, 098 (2016). We are indebted to the communities behind the multiple open-source software packages on which we depend. Test of lepton universality in beauty-quark decays Alguer, M. et al. Thank you for visiting nature.com. Aaij, R. et al. Phys. Glashow, S. L., Iliopoulos, J. The variables m(K++) and mJ/(K++) are used for nonresonant and resonant decays, respectively. (Left) the value of rJ/, relative to the average value of rJ/, measured in two-dimensional bins of the maximum lepton momentum, p(), and the opening angle between the two leptons, (+,). Whenever a process is specified in this paper, the inclusion of the charge-conjugate mode is implied. & Atwood, D. Rate difference between bs+ and bse+e in supersymmetry with large tan . Phys. 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. Provided by the Springer Nature SharedIt content-sharing initiative, Rendiconti Lincei. Quantum field theory allows such a process to be mediated by virtual particles that can have a physical mass larger than the energy available in the interaction. Exp. Lett. Huschle, M. et al. The rJ/ ratio is therefore also computed as a function of different kinematic variables. Phys. Chat with our students. Global analysis of bs anomalies. Phys. Search for B+K++ at the BaBar experiment. The signal is represented by the orange shaded region and the various cascade background contributions by red, dark blue and light blue shaded regions. Test of lepton universality in beauty-quark decays (Journal Article 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. Phys. 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. The LHCb experiment75,76 is instrumented in the region covering the polar angles between 10 and 250mrad around the proton beam axis, in which the products from B hadron decays can be efficiently captured and identified. Zenodo https://doi.org/10.5281/zenodo.4587748. D 96 (2017) 095010 [ arXiv:1704.06659] [ INSPIRE ]. The overall effect of these corrections on the measured value of RK is a relative shift of (+31)%. 2017, 112 (2017). 2020, 40 (2020). Test of lepton flavor universality by the measurement of the B0D*+ branching fraction using three-prong decays. C 74, 2897 (2014); erratum 74, 3179 (2014). 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 Geant4: a simulation toolkit. Analogous background sources with a misidentified particle are reduced by applying a similar veto, but with the lepton mass hypothesis changed to that of a pion (denoted []). Nature 546, 227 . The majority of the sources of systematic uncertainty affect the relative efficiencies between non-resonant and resonant decays. Test of lepton universality in beauty-quark decays - INSPIRE For the muon modes, the superior mass resolution allows a fit in a reduced m(K++) mass range compared with the electron modes. The latter also tend to accumulate around specific values of m(K++). volume18,pages 277282 (2022)Cite this article. Phys. The mass distributions are shown in Extended Data Fig. The Standard Model of particle physics currently provides our best description of fundamental particles and their interactions. There are excellent prospects for all of the above and further measurements with the much larger samples that will be collected with the upgraded LHCb detector from 2022 and, in the longer term, with the LHCb Upgrade II71. Test of lepton flavour universality in beauty-quark decays Phys. 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. Skwarnicki, T. A Study of the Radiative Cascade Transitions between the Upsilon-Prime and Upsilon Resonances. A challenge to lepton universality in B-meson decays | Nature The standard model of particle physics currently provides our best description of fundamental particles and their interactions. 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. Rev. Test of lepton universality in beauty-quark decays LHCb collaboration* The standard model of particle physics currently provides our best description of fundamental particles and their interactions. Lees, J. P. et al. High. Phys. 7 and 8). De Aguiar Francisco,S. De Capua,D. Dutta,C. Fitzpatrick,E. Gersabeck,M. Gersabeck,L. Grillo,M. Hilton,G. Lafferty,J. J. The particles are required to originate from a common vertex, displaced from the protonproton interaction point, with good vertex-fit quality. We acknowledge support from CERN and from the national agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); MOST and NSFC (China); CNRS/IN2P3 (France); BMBF, DFG and MPG (Germany); INFN (Italy); NWO (Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MSHE (Russia); MICINN (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and NSF (United States). D 97, 072013 (2018). Rev. 24, 01025 (2020). Electroweak Penguin Decays at LHCb - ResearchGate Phys. Measurement of the differential branching fraction and forward-backward asymmetry for BK(*)+. For the electron modes, in addition to combinatorial background, other specific background decays contribute significantly in the signal region. Intriguing new result from the LHCb experiment at CERN | CERN 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. D 73, 092001 (2006). & Virto, J. The mass-shape parameters are derived from the calibrated simulation. Phys. D 86, 032012 (2012). Test of lepton universality in beauty-quark decays . Measurement of CP-averaged observables in the B0K*0+ decay. Decays of the form \({B}^{+}\to {\overline{D}}^{0}(\to {K}^{+}{e}^{-}{\overline{\nu }}_{e}){e}^{+}{\nu }_{e}\) also contribute at the level of \({{{\mathcal{O}}}}(1 \%)\) of the B+K+e+e signal; and there is also a contribution from B+J/(e+e)K+ decays, where a photon is emitted but not reconstructed. For the non-resonant candidates, the m(K+e+e)and m(K++)distributions are fitted with a likelihood function that has the B+K++ yield and RK as fit parameters and the resonant decay mode yields incorporated as Gaussian-constraint terms. The pT of the final state particles, the vertex-fit 2 and the significance of the flight distance have the most discriminating power. The double ratio of branching fractions, R(2S), defined by. 108, 081807 (2012). 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. The LHCb trigger system has a hardware stage, based on information from the calorimeter and muon systems, followed by a software stage that uses all the information from the detector, including the tracking, to make the final selection of events to be recorded for subsequent analysis.
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