test of lepton universality in beauty quark decays nature

4. Test of lepton universality in beauty-quark decays Standard Model of particle physics currently predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. 24, 01025 (2020). Eur. Methods A 462, 152155 (2001). Test of lepton universality using B 0 K S 0 l + l- and B + K* + l + l- decays.. 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. Differential branching fractions and isospin asymmetries of BK(*)+ decays. Energy Phys. In the SM description of such processes, these virtual particles include the electroweak force carriers, the , W and Z0 bosons, and the top quark (Fig. Article Exp. Van Hulse, NSC Kharkiv Institute of Physics and Technology (NSC KIPT), Kharkiv, Ukraine, STFC Rutherford Appleton Laboratory, Didcot, UK, S. Easo,R. Nandakumar,A. Papanestis,S. Ricciardi&F. F. Wilson, School of Physics and Astronomy, Monash University, Melbourne, Victoria, Australia, Novosibirsk State University, Novosibirsk, Russia, S. Eidelman,P. Krokovny,V. Kudryavtsev,T. Maltsev,L. Shekhtman&V. Vorobyev, Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden, School of Physics State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China, Y. Gao,Y. Shang,Z. Shen,J. Wang,A. Xu,Z. Xu,S. Zhang&Y. Zhang, National Center for Nuclear Research (NCBJ), Warsaw, Poland, H. K. Giemza,K. Klimaszewski,W. Krzemien,D. Melnychuk,A. Szabelski,A. Ukleja&W. Wislicki, Universit di Roma Tor Vergata, Roma, Italy, Pontifcia Universidade Catlica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil, Universidade Federal do Tringulo Mineiro (UFTM), Uberaba-MG, Brazil, Institute of Particle Physics, Central China Normal University, Wuhan, China, Q. Han,W. Hu,S. Li,Y. Wang,D. Xiao,Y. Xie,M. Xu,H. Yin&D. Zhang, Hangzhou Institute for Advanced Study, UCAS, Hangzhou, China, Instituto de Fisica Corpuscular, Centro Mixto Universidad de Valencia - CSIC, Valencia, Spain, L. Henry,B. K. Jashal,F. Martinez Vidal,A. Oyanguren,C. Remon Alepuz&J. Ruiz Vidal, Nikhef National Institute for Subatomic Physics and VU University Amsterdam, Amsterdam, Netherlands, T. Ketel,H. S. Kuindersma,G. Raven&M. Senghi Soares, National Research Tomsk Polytechnic University, Tomsk, Russia, Faculty of Computer Science, Electronics and Telecommunications, AGH University of Science and Technology, Krakw, Poland, National Research Centre Kurchatov Institute, Moscow, Russia, Universit degli Studi di Milano, Milano, Italy, D. Marangotto,N. Neri&E. Spadaro Norella, MSUIligan Institute of Technology (MSU-IIT), Iligan, Philippines, INFN Sezione di Roma La Sapienza, Roma, Italy, G. Martellotti,D. Pinci,R. Santacesaria,A. Sarti&C. Satriano, Institut fr Physik, Universitt Rostock, Rostock, Germany, Departamento de Fisica, Universidad Nacional de Colombia, Bogota, Colombia, D. A. Milanes,I. 331, 032047 (2011). High. Energy Phys. 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 . Phys. Cascade background of the form \(B\to {H}_{c}(\to {K}^{+}{\ell }^{-}{\overline{\nu }}_{\ell }X){\ell }^{+}{\nu }_{\ell }Y\), where Hc is a hadron containing a c quark (D0, D+, \({D}_{s}^{+}\), \({\Lambda }_{c}^{+}\)), and X, Y are particles that are not included in the B+ candidate, are suppressed by requiring that the kaonlepton invariant mass is in the region m(K+)>\(m_{D^0}\), where \(m_{D^0}\) is the known D0 mass2. Phys. (Right) the bin definition in this two-dimensional space together with the distribution for B+K+e+e (B+J/(e+e)K+) decays depicted as red (blue) contours. Particle physicists have therefore been searching for new physics, that is, new particles and interactions that can explain the SMs shortcomings. Aubert, B. et al. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the standard model, such as a new fundamental interaction between quarks and leptons. 82,83,84,85,86,87,88. Differential branching fraction and angular analysis of \({\Lambda }_{b}^{0}\to \Lambda {\mu }^{+}{\mu }^{-}\) decays. D 94, 072007 (2016). High. B-decay discrepancies after Moriond 2019. s 118, 251802 (2017). This effect is accounted for using simulation (Extended Data Figs. Phys. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Evidence for an excess of \(\overline{B}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }\) decays. 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. Energy Phys. Lyon, J., & Zwicky, R. Resonances gone topsy turvythe charm of QCD or new physics in bs+? Hurth, T., Mahmoudi, F. & Neshatpour, S. Implications of the new LHCb angular analysis of BK*+: hadronic effects or new physics? Measurement of the branching ratio of \({B}^{0}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }\) relative to \(\overline{B}\to \ \ {D}^{(*)}{\ell }^{-}{\overline{\nu }}_{\ell }\) decays with hadronic tagging at Belle. The shape of the B+J/+ background contribution is taken from simulation, but the size with respect to the B+J/K+ mode is constrained using the known ratio of the relevant branching fractions2,94 and efficiencies. (Right, with linear y-scale) the mass is computed only from the track information. Combining the uncertainties gives \({R}_{K}=0.84{6}_{-\ 0.041}^{+\ 0.044}\). 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. Theor. Aaij, R. et al. 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 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. Further tests give good compatibility for subsamples of the data corresponding to different trigger categories and magnet polarities. This gives. Given the scale of the corrections required, comparison of rJ/ with unity is a stringent cross-check of the experimental procedure. The pT of the final state particles, the vertex-fit 2 and the significance of the flight distance have the most discriminating power. The calibrated simulation is used subsequently to obtain the m(K++) mass shape and relative fractions of these background components. D 103, 015030 (2021). Phys. The standard model of particle physics currently provides our best description of fundamental particles and their interactions. 2017, 36 (2017). Bobeth, C., Chrzaszcz, M., van Dyk, D. & Virto, J. The Large Hadron Collider (LHC) is the worlds highest-energy particle accelerator and is situated approximately 100m underground, close to Geneva, Switzerland. 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. Descotes-Genon, S., Hofer, L., Matias, J. The first decay involves the electron and the second the muon, another elementary particle similar to the electron but approximately 200 times heavier. 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). Lett. Rev. Rev. Test of lepton universality with B0K*0+ decays. This can be interpreted as a world-leading test of lepton flavour universality in (2S)+ decays. A distinctive feature of the SM is that the different leptons, electron (e), muon () and tau (\(\tau^{-}\)), have the same interaction strengths. 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. (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. Beauty quarks don't exist in large numbers in the world around as they are incredibly short-lived surviving on average for just a trillionth of a second before transforming or decaying into other particles. 2014, 125 (2014). J. Phys. 2017, 112 (2017). The rJ/ ratio is therefore also computed as a function of different kinematic variables. Extended Data Fig. Lebedev Physical Institute, Russian Academy of Sciences (LPI RAS), Moscow, Russia, Universit della Basilicata, Potenza, Italy, Max-Planck-Institut fr Kernphysik (MPIK), Heidelberg, Germany, Physics and Micro Electronic College, Hunan University, Changsha City, China. The ratio of branching fractions, RH (refs. Long-distance effects in BK* from analyticity. The corresponding significance in terms of standard deviations is computed using the inverse Gaussian cumulative distribution function for a one-sided conversion. The y axis in each panel shows the number of candidates in an interval of the indicated width. 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. Such studies can help to explain the matter-antimatter asymmetryof the Universe. Lett. 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. The performance of the particle identification requirements is then evaluated from the proportion of events in these samples which fulfil the particle identification selection criteria. Commun. Aad, G. et al. Rev. One method to search for new physics is to compare measurements of the properties of hadron decays, where hadrons are bound states of quarks, with their SM predictions. 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). 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. High. 126, 161801 (2021). Comput. J. Nucl. High. 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. Bainbridge, R. on behalf of the CMS collaboration Recording and reconstructing 10 billion unbiased b hadron decays in CMS. The measurement made by the LHCb team compares two types of decays of beauty quarks. J. Phys. Search for lepton-universality violation in B+K++ decays. In summary, in the dilepton mass-squared region 1.10.95 due to the comparatively low yield of B+K+e+e events. An uncertainty comparable to that from the modelling of the signal and background components is induced by the limited sizes of calibration samples. Search for the decays \({B}_{s}^{0}\to {\tau }^{+}{\tau }^{-}\) and B0+. The J/ meson consists of a charm quark and antiquark, \(c\overline{c}\), and is produced resonantly at q2=9.59GeV2c4. 4 Likelihood function from the fit to the nonresonant. Internet Explorer). D 96, 093006 (2017). Following the procedure described in refs. 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. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. 0 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. In addition, rJ/ is computed in two-dimensional intervals of reconstructed quantities (Extended Data Fig. J. The PVs are reconstructed by searching for space points where an accumulation of track trajectories is observed. Lett. Lepton-flavor-dependent angular analysis of BK*+. This causes misidentification backgrounds to populate a range of K masses but only a peak in the Ke mass. The mass distributions are shown in Extended Data Fig. Energy Phys. Phys. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. B Rev. J. A. Rodriguez Lopez, Universitt Bonn Helmholtz-Institut fr Strahlen und Kernphysik, Bonn, Germany, Hanoi University of Science, Hanoi, Vietnam, P.N. Theor. Khodjamirian, A., Mannel, T., Pivovarov, A. The analysis strategy aims to reduce systematic uncertainties induced in modelling the markedly different reconstruction of decays with muons in the final state, compared with decays with electrons. & Virto, J. Lett. C 74, 2897 (2014); erratum 74, 3179 (2014). Huschle, M. et al. 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. 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 of particle physics currently provides our best description of fundamental particles and their interactions. 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. Test of lepton universality using B 0 K S0 l + l - and B + K* + l + l - decays. Ratio between the likelihood value (L) and that found by the fit (\({L}_{\max }\)) as a function of RK. Ser. 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. Phys. The 3,85070 B+K++ decay candidates that are observed are used to compute the B+K++ branching fraction as a function of q2. Other explanations of the data involve a variety of extensions to the SM, such as supersymmetry, extended Higgsboson sectors and models with extra dimensions. On the standard model predictions for RK and \({R}_{{K}^{* }}\). Rev. 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. Stanford Libraries' official online search tool for books, media, journals, databases, government documents and more. CMS collaboration Angular analysis of the decay B0K*0+ from pp collisions at \(\sqrt{s}=8\) TeV. Alok, A. K., Dighe, A., Gangal, S. & Kumar, D. Continuing search for new physics in bs decays: two operators at a time. Beauty quarks test lepton universality - CERN Courier Flavour physics Feature Beauty quarks test lepton universality 23 March 2018 A series of measurements from LHCb and B-factory experiments have tested whether the interactions of charged leptons agree with the Standard Model. which does not benefit from the same cancellation of systematic effects. 2006, 026 (2006). Rev. Angular analysis of the B+K*++ decay. 9,10), is defined in the dilepton mass-squared range \({q}_{\min }^{2} < {q}^{2} < {q}_{\max }^{2}\) as. Phys. 2014, 133 (2014). http://creativecommons.org/licenses/by/4.0/, Heavy flavour physics and CP violation at LHCb: A ten-year review, New UTfit analysis of the unitarity triangle in the CabibboKobayashiMaskawa scheme, Hint of crack in standard model vanishes in LHC data, How the revamped Large Hadron Collider will hunt for new physics. Prog. Correlations in the systematic uncertainties between different trigger categories and run periods are taken into account. C 73, 2646 (2013). Measurements of the angular distributions in the decays BK(*)+ at CDF. Calculation of the SM predictions for the branching fractions of B+K++ and B+K+e+e decays is complicated by the strong nuclear force that binds together the quarks into hadrons, as described by quantum chromodynamics (QCD). Measurement of an excess of \(\overline{B}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }\) decays and implications for charged Higgs bosons. Reassessing the discovery potential of the B + K + + l + +l - decays in the large-recoil region: SM challenges and BSM opportunities, Physical Review D93: 014028. arXiv:1412.3183. Measurements of branching fractions, rate asymmetries, and angular distributions in the rare decays BK+ and BK*+. D 96 (2017) 095010 [ arXiv:1704.06659] [ INSPIRE ]. This resolution scaling changes the migration of candidates into the q2 region of interest by less than 1%. The Belle collaboration et al. This symmetry is called lepton avour universality (LFU) and is established in for example /0! The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Rev. Straub, D. M. flavio: a python package for flavour and precision phenomenology in the standard model and beyond. 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. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on protonproton collision data collected with the LHCb detector at CERNs Large Hadron Collider. Lett. 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. 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. Rev. 12, 131 (2014). Energy Phys. 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. According to the Standard Model of particle physics, particles such as beauty quarks should decay into either muons or electrons in equal measure. Eur. Assuming that the observed rJ/ variation in such distributions reflects genuine mis-modelling of the efficiencies, rather than statistical fluctuations, and taking into account the spectrum of the relevant variables in the non-resonant decay modes, a total shift on RK is computed for each of the variables examined. A. Bertolin. Use the Previous and Next buttons to navigate the slides or the slide controller buttons at the end to navigate through each slide. 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). Sifting through proton . Rev. B High Energy Phys. The results are consistent between the different data-taking periods and with previous LHCbmeasurements37. Lange, D. J. 1. In the meantime, to ensure continued support, we are displaying the site without styles Whenever a process is specified in this paper, the inclusion of the charge-conjugate mode is implied. Lett. J. Energy Phys. CERN https://cds.cern.ch/record/2636441 (2019). 124, 161803 (2020). Ghez,J. F. Marchand,M.-N. Minard,B. Pietrzyk,B. Quintana,M. Reboud&S. TJampens, Center for High Energy Physics, Tsinghua University, Beijing, China, C. Chen,J. 2,65), the RK ratio is determined via the double ratio of branching fractions, In this equation, each branching fraction can be replaced by the corresponding event yield divided by the appropriate overall detection efficiency (Methods), as all other factors needed to determine each branching fraction individually cancel out. Introduction In the Standard Model of particle physics (SM), the interactions of the three lepton avours with the gauge bosons exhibit the same coupling strength. san antonio gunslingers 2021 owner, poinciana high school shooting,

Statsmodels Prediction Interval, Sample Political Campaign Manager Contract, Articles T