Test of lepton universality using \({\Lambda }_{b}^{0}\to p{K}^{-}{\ell }^{+}{\ell }^{-}\) decays. Measurable quantities can be predicted precisely in the decays of a charged beauty hadron, B +, into a charged kaon, K +, and two charged leptons, + . The CMS collaboration Measurement of angular parameters from the decay B0K*0+ in proton-proton collisions at \(\sqrt{s}=\) 8 TeV. In the resonant-mode distributions, some fit components are too small to be visible. Improved lepton universality measurements show agreement with the The major challenge of the measurement is then correcting for the efficiency of the selection requirements used to isolate signal candidates and reduce background. Similarly, the variations seen in rJ/ as a function of all other reconstructed quantities examined are compatible with the systematic uncertainties assigned. Rev. For the muon modes, the superior mass resolution allows a fit in a reduced m(K++) mass range compared with the electron modes. Publishers note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Phys. Methods A 462, 152155 (2001). Rev. In summary, in the dilepton mass-squared region 1.1Has a new particle called a 'leptoquark' been spotted at CERN? The LHCb Collaboration, Test of lepton universality in beauty-quark decays, Nature Physics 18, (2022) 277-282. Likhomanenko, T. et al. The distributions of the B+ transverse momentum (pT, left) and the ratio rJ/ (right) relative to its average value \(< {r}_{J/\psi } >\) as a function of pT. The pT of the final state particles, the vertex-fit 2 and the significance of the flight distance have the most discriminating power. High Energy Phys. Belyaev, I. et al. Lees, J. P. et al. Lett. The electron and muon veto cuts differ given the relative helicity suppression of ++ decays. 7 and 8). PDF Test of lepton universality in beauty-quark decays - arXiv & Langford J. Hirose, S. et al. Ser. & Tech. J. Instrum. The profile likelihood is given in Methods. The proportion of signal candidates that migrate in and out of the q2 region of interest is on the order of 10%. Aaij, R. et al. 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. Distribution of the invariant mass mJ/(K++) for resonant candidates in the (left) sample previously analysed11 and (right) the new data sample. The data were recorded during 2011, 2012 and 20152018 with centre-of-mass energy of the collisions of 7, 8 and 13TeV and correspond to an integrated luminosity of 9fb1. Left: the SM contribution involves the electroweak bosons ,W+ and Z0, and the up-type quarks , \(\bar{c}\) and \(\bar{t}\). J. Instrum. The Standard Model predicts that this occurs via electroweak bosons and the W + and Z 0 particles. 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. 2). This uncertainty includes both statistical and systematic effects, where the latter dominate. D 92, 075022 (2015). Uncertainties on the data points are statistical only and represent one standard deviation. 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. The LHCb collaboration et al. Phys. A. 118, 031802 (2017). Bordone, M., Isidori, G. & Pattori, A. The uncertainties on parameters used in the simulation model of the signal decays affect the q2 distribution and hence the selection efficiency. Breiman, L., Friedman, J. H., Olshen, R. A., & Stone C. J. Rev. The large interaction strengths preclude predictions of QCD effects with the perturbation techniques used to compute the electroweak force amplitudes, and only approximate calculations are currently possible. The authors declare no competing interests. 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. Nucl. (Right, with linear y-scale) the mass is computed only from the track information. The value of q2 is calculated using only the lepton momenta, without imposing any constraint on the m(K++) mass. Rev. Phys. For the electron mode, this requirement is illustrated in Extended Data Fig. D 89, 074014 (2014). van Dyk, D et al. High. De Aguiar Francisco,S. De Capua,D. Dutta,C. Fitzpatrick,E. Gersabeck,M. Gersabeck,L. Grillo,M. Hilton,G. Lafferty,J. J. 2017, 112 (2017). 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. Further tests give good compatibility for subsamples of the data corresponding to different trigger categories and magnet polarities. Angular analysis of \({B}_{d}^{0}\to {K}^{* }{\mu }^{+}{\mu }^{-}\) decays in pp collisions at \(\sqrt{s}=8\) TeV with the ATLAS detector. This charmonium resonance subsequently decays into two leptons, J/+. Other explanations of the data involve a variety of extensions to the SM, such as supersymmetry, extended Higgsboson sectors and models with extra dimensions. A. Rodriguez Lopez, Universitt Bonn Helmholtz-Institut fr Strahlen und Kernphysik, Bonn, Germany, Hanoi University of Science, Hanoi, Vietnam, P.N. The y axis in each panel shows the number of candidates in an interval of the indicated width. Phys. volume18,pages 277282 (2022)Cite this article. Aaij, R. et al. Ratio between the likelihood value (L) and that found by the fit (\({L}_{\max }\)) as a function of RK. The latest LHCb result is the first test of lepton universality made using the decays of beauty baryonsthree-quark particles containing at least one beauty quark. 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. A distinctive feature of the SM is that the different leptons, electron (e), muon () and tau (\(\tau^{-}\)), have the same interaction strengths. 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. The k-folding technique is used in the training and testing81. The BDT output is not strongly correlated with q2, and the same classifiers are used to select the respective resonant decays. Eur. LHCb collaboration et al. The consistency of this ratio with unity demonstrates control of the efficiencies well in excess of that needed for the determination of RK. Bremsstrahlung photons can be added to none, either or both of the final-state e+ and e candidates. Lees, J. P. et al. Bainbridge, R. on behalf of the CMS collaboration Recording and reconstructing 10 billion unbiased b hadron decays in CMS. Phys. Pion electronic decay and lepton universality License CC BY 4.0 Authors: Dinko Pocanic Abstract In common with a number of simple processes involving elementary particles, charged pion decays. Phys. (Left, with log y-scale) the bremsstrahlung correction to the momentum of the electron is applied, resulting in a tail to the right. J. (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. 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. Lees, J. P. et al. Get the most important science stories of the day, free in your inbox. LHCb collaboration. J. C76, 440 (2016). D 93, 014028 (2016). s Different types of charged particles are distinguished using information from two ring-imaging Cherenkov detectors, a calorimeter and a muon system76. J. C77, 377 (2017). Reassessing the discovery potential of the BK*+ decays in the large-recoil region: SM challenges and BSM opportunities. J. 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. Hurth, T., Mahmoudi, F. & Neshatpour, S. Implications of the new LHCb angular analysis of BK*+: hadronic effects or new physics? 108, 081807 (2012). J. The double ratio of branching fractions, R(2S), defined by. Bhupal Dev and A. Soni, {R}_ {D^ {\left (\ast \right)}} anomaly: A possible hint for natural supersymmetry with R-parity violation, Phys. Right: a possible new physics contribution to the decay with a hypothetical leptoquark (LQ) which, unlike the electroweak bosons, could have different interaction strengths with the different types of leptons. Particle Physics (4th ed. B High. 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/. High. Methods A 764, 150155 (2014). The decays used in this analysis to study lepton universality are extremely rare. 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.
Scripture For Deacons Meeting, Articles T