For the electron modes, in addition to combinatorial background, other specific background decays contribute significantly in the signal region. For decays with H=K+ and H=K*0 such ratios, denoted by RK and RK*0, respectively, have previously been measured by the Large Hadron Collider beauty (LHCb)11,12, Belle13,14 and BaBar15 collaborations. After the application of the selection requirements, the resonant and non-resonant decays are clearly visible in the mass distributions (Fig. Test of lepton universality in beauty-quark decays (Journal Article Straub, D. M. flavio: a python package for flavour and precision phenomenology in the standard model and beyond. Gligorov, V. V. & Williams, M. Efficient, reliable and fast high-level triggering using a bonsai boosted decision tree. Uncertainties on the data points are the combination of statistical and systematic and represent one standard deviation. Improved lepton universality measurements show agreement with the Whenever B+J/(+)K+ events are used to correct the simulation, the correlations between calibration and measurement samples are taken into account in the results and cross-checks presented in this paper. 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. CMS collaboration Angular analysis of the decay B0K*0+ from pp collisions at \(\sqrt{s}=8\) TeV. For illustration, the expected distribution of signal candidates with true q2 outside the interval [1.1,6.0]GeV2/c4 is shown as a grey dashed and dotted line. Comput. Candidate B+K++ decays are found by combining the reconstructed trajectory (track) of a particle identified as a charged kaon, together with the tracks from a pair of well-reconstructed oppositely charged particles identified as either electrons or muons. Flavor probes of axion-like particles | SpringerLink Given the scale of the corrections required, comparison of rJ/ with unity is a stringent cross-check of the experimental procedure. Back,T. Blake,A. Brossa Gonzalo,M. F. Cicala,C. M. Costa Sobral,L. M. Garcia Martin,T. Gershon,R. J. The corresponding significance in terms of standard deviations is computed using the inverse Gaussian cumulative distribution function for a one-sided conversion. Towards the discovery of new physics with lepton-universality ratios of bs decays. 7 and 8). 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. Aaij, R. et al. 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. 331, 032047 (2011). PDF Beauty quarks test lepton universality - cds.cern.ch Nat. Such decays are highly suppressed1, and the fraction of B+ hadrons that decay into this final state (the branching fraction, \({{{\mathcal{B}}}}\)) is on the order of 106 (ref. Davidson, N., Przedzinski, T. & Was, Z. Angular analysis of the B+K*++ decay. Energy Phys. Rev. An angular analysis of the electron mode, where SM-like behaviour might be expected in the light of the present results and those from \(\overline{b}\to \overline{s}{\mu }^{+}{\mu }^{-}\) decays, would allow the formation of ratios between observable quantities other than branching fractions, enabling further precise tests of lepton universality16,18,31,67,68. Altmannshofer, W. & Yavin, I. Particle Physics (4th ed. 125, 011802 (2020). (Left, with log y-scale) the bremsstrahlung correction to the momentum of the electron is applied, resulting in a tail to the right. 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. Get the most important science stories of the day, free in your inbox. As a result, the different lepton types should be created equally often in particle transformations, or "decays", once differences in their mass are accounted for. J. 199, 86101 (2016). The invariant mass of the final state particles, m(K++), is used to discriminate between signal and background contributions, with the signal expected to accumulate around the known mass of the B+ meson. Measurement of the differential branching fraction and forward-backward asymmetry for BK(*)+. 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. 53, 270278 (2006). Phys. Phys. Fan,Y. Gan,G. Gong,C. Gu,F. Jiang,Y. Kang,X. Liu,Y. Luo,H. Mu,Z. Ren,J. Wang,M. Wang,Z. Wang,L. Xu,D. Yang,Z. Yang,M. Zeng,L. Zhang&X. Zhu, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK, P. E. L. Clarke,R. Currie,S. Eisenhardt,S. Gambetta,K. Gizdov,S. E. Mitchell,F. Muheim,M. Needham,S. Petrucci,G. Robertson,M. R. J. Williams&J. For the RK measurement, candidate events are required to have passed a hardware trigger algorithm that selects either a high-pT muon, or an electron, hadron or photon with high transverse energy deposited in the calorimeters. Rev. D 96 (2017) 095010 [ arXiv:1704.06659] [ INSPIRE ]. 126, 161801 (2021). This is the most precise measurement to date and is consistent with the SM expectation, 1.000.01 (refs. Phys. In the resonant-mode distributions, some fit components are too small to be visible. Thank you for visiting nature.com. Instrum. The muon BDT classifier has similar performance. Previous measurements have shown a wide range of particle decays are consistent with this principle of lepton universality. Rev. Energy Phys. Altmannshofer, W. & Straub, D. M. New physics in BK*? J. The Standard Model of particle physics currently provides our best description of fundamental particles and their interactions. Test of lepton universality using \({\Lambda }_{b}^{0}\to p{K}^{-}{\ell }^{+}{\ell }^{-}\) decays. The y-axis in each figure shows the number of candidates in an interval of the indicated width. C 79, 714 (2019); addendum 80, 511 (2020). CERN experiment found that beauty quarks not behaving in the way they 118, 251802 (2017). 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. Sci. Measurements of other RH observables with the full LHCb dataset will provide further information on the quark-level processes measured. Search for the decays \({B}_{s}^{0}\to {\tau }^{+}{\tau }^{-}\) and B0+. D 68, 094016 (2003). 2020, 083C01 (2020). Such studies can help to explain the matter-antimatter asymmetryof the Universe. Nucl. The effect on RK is at the 1% level. 5, together with the spectra expected for the resonant and non-resonant decays. Belyaev, I. et al. J. Aebischer, J. et al. Wei J.-T. et al. Martnez Santos, D. & Dupertuis, F. Mass distributions marginalized over per-event errors. Rev. Use the Previous and Next buttons to navigate the slides or the slide controller buttons at the end to navigate through each slide. Uncertainties on the data points are statistical only and represent one standard deviation. D 95, 035029 (2017). Measurement of an excess of \(\overline{B}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }\) decays and implications for charged Higgs bosons. Phys. 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). Part. PHOTOS interface in C++: technical and physics documentation. J. Particle Data Group et al. Sun, Institute of Nuclear Physics, Moscow State University (SINP MSU), Moscow, Russia, I. Belov,A. Berezhnoy,I. V. Gorelov,M. Korolev,A. Leflat,N. Nikitin,D. Savrina&V. Zhukov, Institute of Theoretical and Experimental Physics NRC Kurchatov Institute (ITEP NRC KI), Moscow, Russia, I. Belyaev,A. Danilina,V. Egorychev,D. Golubkov,P. Gorbounov,A. Konoplyannikov,T. Kvaratskheliya,V. Matiunin,T. Ovsiannikova,D. Pereima,D. Savrina,A. Semennikov&A. Smetkina, INFN Laboratori Nazionali di Frascati, Frascati, Italy, G. Bencivenni,L. Calero Diaz,S. Cali,P. Campana,P. Ciambrone,P. De Simone,P. Di Nezza,M. Giovannetti,G. Lanfranchi,G. Morello,M. Palutan,M. Poli Lener,M. Rotondo,M. Santimaria&B. Sciascia, LPNHE, Sorbonne Universit, Paris Diderot Sorbonne Paris Cit, CNRS/IN2P3, Paris, France, E. Ben-Haim,P. Billoir,L. Calefice,M. Charles,L. Del Buono,S. Esen,M. Fontana,V. V. Gligorov,T. Grammatico,F. Polci,R. Quagliani,D. Y. Tou,P. Vincent&S. G. Weber, Universita degli Studi di Padova, Universita e INFN, Padova, Padova, Italy, A. Bertolin,D. Lucchesi,M. Morandin,L. Sestini,G. Simi&D. Zuliani, Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Krakw, Poland, J. Bhom,J. T. Borsuk,J. Brodzicka,A. Chernov,M. Chrzaszcz,M. W. Dudek,A. Dziurda,M. Goncerz,M. Jezabek,W. Kucewicz,M. Kucharczyk,T. Lesiak,J. J. Malczewski,A. Ossowska,K. Prasanth,M. Witek&M. Zdybal, School of Physics and Technology, Wuhan University, Wuhan, China, L. Bian,H. Cai,B. Fang,X. Huang,L. Sun&J. Wang, S. Bifani,R. Calladine,G. Chatzikonstantinidis,N. Cooke,J. Plews,M. W. Slater,P. N. Swallow&N. K. Watson, Universit di Modena e Reggio Emilia, Modena, Italy, Department of Physics, University of Oxford, Oxford, UK, M. Bjrn,K. M. Fischer,F. Goncalves Abrantes,B. R. Gruberg Cazon,T. H. Hancock,N. Harnew,M. John,L. Li,S. Malde,R. A. Mohammed,C. H. Murphy,T. Pajero,M. Pili,H. Pullen,V. Renaudin,A. Rollings,L. G. Scantlebury Smead,J. C. Smallwood,F. Suljik,G. Wilkinson&Y. Zhang, Massachusetts Institute of Technology, Cambridge, MA, USA, T. Boettcher,D. C. Craik,O. Kitouni,C. Weisser&M. Williams, National Research University Higher School of Economics, Moscow, Russia, A. Boldyrev,D. Derkach,M. Hushchyn,M. Karpov,A. Maevskiy,F. Ratnikov,A. Ryzhikov&A. Ustyuzhanin, Budker Institute of Nuclear Physics (SB RAS), Novosibirsk, Russia, A. Bondar,S. Eidelman,P. Krokovny,V. 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. 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 []). Phys. 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. J. Phys. 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. Rev. If material is not included in the articles Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. New tests of lepton universality show the same pattern as deviations Test of lepton universality with beauty baryons, RpK ADS Methods A 506, 250303 (2003). No significant trend is observed in the differential determination of rJ/ as a function of any considered variable. LHCb topological trigger reoptimization. Distribution of the invariant mass m(J/)(K++) for candidates with electron (left) and muon (right) pairs in the final state for the non-resonant B+K++ signal channels (top) and resonant B+J/(+)K+ decays (bottom). Phys. Measurements of the S-wave fraction in B0K++ decays and the B0K*(892)0+ differential branching fraction. 12, 040 (2007). The LHCb simulation application, Gauss: design, evolution and experience. When compared with the 20% shift that these corrections induce in the measurement of rJ/, this demonstrates the robustness of the double-ratio method in suppressing systematic biases that affect the resonant and non-resonant decay modes similarly. New physics in bs+ confronts new data on lepton universality. 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. 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The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. 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. Pion electronic decay and lepton universality - ResearchGate The red line indicates the prediction from the SM. They involve the transformation of a beauty quark into a strange quark (bs), a process that is highly suppressed in the SM and can be affected by the existence of new particles. Lett. The trigger response is corrected using weights applied to simulation as a function of variables relevant to the trigger algorithms. 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.