The region to the left of the vertical dashed line is rejected. The classifier includes the following variables: the pT of the B+, K+ and dilepton candidates, and the minimum and maximum pT of the leptons; the B+, dilepton and K+\({\chi }_{{{{\rm{IP}}}}}^{2}\) with respect to the associated PV, where \({\chi }_{{{{\rm{IP}}}}}^{2}\) is defined as the difference in the vertex-fit 2 of the PV reconstructed with and without the considered particle; the minimum and maximum \({\chi }_{{{{\rm{IP}}}}}^{2}\) of the leptons; the B+ vertex-fit quality; the statistical significance of the B+ flight distance; and the angle between the B+ candidate momentum vector and the direction between the associated PV and the B+ decay vertex. EPJ Web Conf. High Energy Phys. Measurement of \({{{\mathcal{R}}}}(D)\) and \({{{\mathcal{R}}}}({D}^{* })\) with a semileptonic tagging method. High Energy Phys. The measurement made by the LHCb team compares two types of decays of beauty quarks. In addition to the process discussed above, the K++ final state is produced via a \({B}^{+}\to {X}_{q\overline{q}}{K}^{+}\) decay, where \({X}_{q\overline{q}}\) is a bound state (meson) such as the J/. The significance of this discrepancy is 3.1standard deviations, giving evidence for the violation of lepton universality in these decays. To train the classifier, simulated non-resonant B+K++ decays are used as a proxy for the signal and non-resonant K++ candidates selected from the data with m(K++)>5.4GeV c2 are used as a background sample. 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. Angular analysis of the B+K*++ decay. The LHCb simulation application, Gauss: design, evolution and experience. Wehle, S. et al. 2019, 123C01 (2019); erratum 2020, 029201 (2020). Lett. Background from other exclusive B-hadron decays requires at least two particles to be misidentified. Altmannshofer, W., Niehoff, C., Stangl, P. & Straub, D. M. Status of the BK*+ anomaly after Moriond 2017. 2020, 083C01 (2020). The kinematic correlation between m(K+e+e)and q2 means that, irrespective of misreconstruction effects, the latter background can only populate the m(K+e+e) region well below the signal peak. The theory predicts that the different charged leptons, the electron, muon and tau, have . Test of lepton universality in beauty-quark decays - INSPIRE The y axis in each panel shows the number of candidates in an interval of the indicated width. Uncertainties on the data points are the combination of statistical and systematic and represent one standard deviation. The fits to the non-resonant (resonant) decay modes in different data-taking periods and trigger categories are shown in Extended Data Fig. Only potentially interesting events, selected using real-time event filters referred to as triggers, are recorded. Get the most important science stories of the day, free in your inbox. 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. In summary, in the dilepton mass-squared region 1.1[2103.11769] Test of lepton universality in beauty-quark decays - arXiv.org Rev. 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. For the electron modes, a wider mass region is needed to perform an accurate fit, but the range chosen suppresses any significant contribution from decays with two or more additional pions that are not reconstructed. 664, 082025 (2015). C 73, 2646 (2013). Theor. Measurements from Run 1 of decays of beauty hadrons at the LHCb experiment, in addition to earlier results from the B-facto - Beauty quarks test lepton universality A series of measurements from LHCb and B-factory experiments have tested whether the interactions of charged leptons agree with the Standard Model. Lees, J. P. et al. 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. Lepton Flavour Universality can be studied in two classes of B meson decays in which a beauty b quark can be transformed into either a strange quark (bs) or into a charm quark (bc). The results supersede those of the previous LHCb analysis. B 781, 517541 (2018). The theory predicts that the di erent charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Aaij, R. et al. The signal mass shapes of the electron modes are described with the sum of three distributions, which model whether the ECAL energy deposit from a bremsstrahlung photon was added to both, either or neither of the e candidates. The energy of any such deposit is added to the electron energy that is derived from the measurements made in the tracker. Combining the uncertainties gives \({R}_{K}=0.84{6}_{-\ 0.041}^{+\ 0.044}\). Angular analysis of the B0K*0+ decay using 3fb1 of integrated luminosity. Measurable quantities can be predicted precisely in the decays of a charged beauty hadron, B+, into a charged kaon, K+, and two charged leptons, +. Khodjamirian, A., Mannel, T., Pivovarov, A. Correlations in the systematic uncertainties between different trigger categories and run periods are taken into account. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. High. Instrum. The bias is found to be 1% of the statistical precision and thus negligible with respect to other sources of systematic uncertainty. J. & Atwood, D. Rate difference between bs+ and bse+e in supersymmetry with large tan . Phys. Measurable quantities can be predicted precisely in the decays of a charged beauty hadron, B +, into a charged kaon, K +, and two charged leptons, + . D 89, 074014 (2014). Novel Tests of Lepton Universality Boost Evidence for 'New Physics LHCb collaboration Physics case for an LHCb upgrade IIopportunities in flavour physics, and beyond, in the HL-LHC era. 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. C 79, 714 (2019); addendum 80, 511 (2020). 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. 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. The EvtGen particle decay simulation package. Measurements of branching fractions, rate asymmetries, and angular distributions in the rare decays BK+ and BK*+. Phys. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. For the electron modes, in addition to combinatorial background, other specific background decays contribute significantly in the signal region. The ATLAS and CMS experiments may also be able to contribute73,74. The fit projections for the m(K++) and mJ/(K++) distributions are shown in Fig. Such background is reduced to a negligible level by particle identification criteria. s Mar 22, 2019. 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. 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 at CERN's Large Hadron Collider. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Test of lepton universality in beauty-quark decays (Journal Article Google Scholar. Altmannshofer, W. & Straub, D. M. New physics in BK*? Hint of lepton flavour non-universality in B meson decays. 0 High. The analogous ratio has also been measured for \({\Lambda }_{b}^{0}\) decays with H=pK and is compatible with unity at the level of one standard deviation23. Article Rev. J. Mod. Bharucha, A., Straub, D. M. & Zwicky, R. BV+ in the standard model from light-cone sum rules. Sun&Z. Yang, Guangdong Provencial Key Laboratory of Nuclear Science, Institute of Quantum Matter, South China Normal University, Guangzhou, China, Institute for Nuclear Research of the Russian Academy of Sciences (INR RAS), Moscow, Russia, A. Butkevich,S. Filippov,E. Gushchin,L. Kravchuk&S. Luchuk, R. Calabrese,M. Fiorini,P. Griffith,E. Luppi,L. Minzoni,L. L. Pappalardo,I. Slazyk&L. Tomassetti, INFN Sezione di Milano-Bicocca, Milano, Italy, M. Calvi,S. Capelli,P. Carniti,D. Fazzini,J. Garca Pardias,C. Gotti,M. Martinelli,C. Matteuzzi,S. Meloni&E. B. Shields, Universit di Milano Bicocca, Milano, Italy, M. Calvi,S. Capelli,P. Carniti,D. Fazzini,J. Garca Pardias,L. Martinazzoli,M. Martinelli,S. Meloni&E. B. Shields, DS4DS, La Salle, Universitat Ramon Llull, Barcelona, Spain, M. Calvo Gomez,A. Camboni,E. Golobardes,N. Valls Canudas&X. Vilasis-Cardona, University of Chinese Academy of Sciences, Beijing, China, A. F. Campoverde Quezada,Y. Test of lepton universality in beauty-quark decays LHCb collaboration Abstract The Standard Model of particle physics currently provides our best description of fundamental particles and their interactions. Bordone, M., Isidori, G. & Pattori, A. Energy Phys. Eur. Simulated events are weighted to correct for the imperfect modelling using control channels. Lett. It would therefore constitute a significant evolution in our understanding and would challenge an inference based on a wealth of experimental data in other processes. Ciuchini, M. et al. J. CERN https://cds.cern.ch/record/2636441 (2019). A multivariate algorithm is used for the identification of displaced vertices consistent with the decay of a B hadron77,78. Allison, J. et al. The Belle II physics book. Rev. 103, 171801 (2009). The profile likelihood for the fit to the non-resonant decays is shown in Extended Data Fig. The analysis technique used to obtain the results presented in this paper is essentially identical to that used to obtain the previous LHCb RK measurement, described in ref. 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. The distributions are all normalised to unity.
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