test of lepton universality in beauty quark decays nature

Again, no significant trend is seen. ). Bay,V. Bellee,F. Blanc,S. A. Bouchiba,S. Celani,S. Cholak,M. De Cian,S. Ek-In,L. Ferreira Lopes,E. Graverini,G. Haefeli,D. Hill,V. S. Kirsebom,V. Macko,M. Marinangeli,T. Nakada,T. Nanut,T. D. Nguyen,C. Nguyen-Mau,G. Pietrzyk,F. Redi,A. Aaltonen, T. et al. J. LHCb collaboration. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction. Bainbridge, R. on behalf of the CMS collaboration Recording and reconstructing 10 billion unbiased b hadron decays in CMS. Control channels are used to calibrate the simulation to correct for the imperfect modelling of the B+ production kinematics and various aspects of the detector response. Such studies can help to explain the matter-antimatter asymmetryof the Universe. 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. Measurable quantities can be predicted precisely in the decays of a charged beauty hadron, B +, into a charged kaon, K +, and two charged leptons, + . Lessons from the B0,+K*0,++ angular analyses. Rev. A. Boelhauve,L. Calefice,E. DallOcco,H.-P. Dembinski,Q. Fuehring,L. L. Gerken,K. Heinicke,S. E. Hollitt,P. Ibis,V. Jevtic,B. Khanji,J. Langer,V. Lisovskyi,P. Mackowiak,G. Meier,A. Mdden,T. Mombcher,N. S. Nolte,M. Saur,M. Schellenberg,A. Seuthe,B. Spaan,H. Stevens&D. Wiedner, European Organization for Nuclear Research (CERN), Geneva, Switzerland, F. Alessio,L. An,C. Bertella,F. Betti,M. P. Blago,N. Bondar,A. Boyer,M. Brodski,C. Burr,J. Buytaert,W. Byczynski,M. Cattaneo,G. Cavallero,Ph. 103, 171801 (2009). Back,T. Blake,A. Brossa Gonzalo,M. F. Cicala,C. M. Costa Sobral,L. M. Garcia Martin,T. Gershon,R. J. In both cases, for both signal and background, the efficiency of the BDT selection has negligible dependence on m(K++) and q2 in the regions used to determine the event yields. Phys. B Energy Phys. Google Scholar. LHCb collaboration LHCb detector performance. The expected values from simulated events are used to constrain the fraction of signal decays in each of these categories. The distributions are all normalised to unity. Differential branching fractions and isospin asymmetries of BK(*)+ decays. & Atwood, D. Rate difference between bs+ and bse+e in supersymmetry with large tan . Phys. Rev. The Belle collaboration et al. 7 and 8). J. In addition to the LHCb result, the measurements by the BaBar15 and Belle13 collaborations, which combine B+K++ and \({B}^{0}\to {K}_{{{{\rm{S}}}}}^{0}{\ell }^{+}{\ell }^{-}\) decays, are also shown. Test of lepton flavour universality in beauty-quark decays The theory predicts that the different charged leptons, the electron, muon and tau, have . 82,83,84,85,86,87,88. The LHCb collaboration et al. Altmannshofer, W., Niehoff, C., Stangl, P. & Straub, D. M. Status of the BK*+ anomaly after Moriond 2017. Eur. J. Search for B+K++ at the BaBar experiment. Energy Phys. oscillation frequency, Probing CP symmetry and weak phases with entangled double-strange baryons, Polarization and entanglement in baryonantibaryon pair production in electronpositron annihilation, The Higgs boson implications and prospects for future discoveries, http://opendata.cern.ch/record/410/files/LHCb-Data-Policy.pdf, https://www.hepdata.net/record/ins1852846?version=1. A. Monroy&J. Stanford Libraries' official online search tool for books, media, journals, databases, government documents and more. These two processes are separated by applying a requirement on q2. Lett. This is the most precise measurement to date and is consistent with the SM expectation, 1.000.01 (refs. Hurth, T., Mahmoudi, F. & Neshatpour, S. Implications of the new LHCb angular analysis of BK*+: hadronic effects or new physics? The effect on RK is at the 1% level. For the muon modes, the superior mass resolution allows a fit in a reduced m(K++) mass range compared with the electron modes. Phys. C 73, 2646 (2013). D 94, 072007 (2016). EPJ Web Conf. 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. and JavaScript. ADS 24, 01025 (2020). Aaij, R. et al. A comparable uncertainty arises from the limited size of the calibration samples, with negligible contributions from the calibration of the B+ production kinematics and modelling of the selection and particle-identification efficiencies. Rev. Steven D. Bass, Albert De Roeck & Marumi Kado, Nature Physics 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. Program of Guangzhou (China); RFBR, RSF and Yandex LLC (Russia); GVA, XuntaGal and GENCAT (Spain); the Leverhulme Trust, the Royal Society and UKRI (United Kingdom). 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. Extended Data Fig. 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. 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. 5). A significant proportion (0.7%) of this uncertainty comes from the limited knowledge of the K spectrum in B(0,+)K+(,0)e+e decays. C 80, 252 (2020). 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. 0 2018, 47 (2018). 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. 4. We investigate the phenomenology of an ALP with flavor-changing couplings, and present a comprehensive analysis of quark and lepton flavor-changing observables within a general ALP effective field theory. Methods A 764, 150155 (2014). The uncertainties on parameters used in the simulation model of the signal decays affect the q2 distribution and hence the selection efficiency. 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. The B+J/(+)K+ decays are not suppressed and hence have a branching fraction orders of magnitude larger than that of B+K++ decays. ISSN 1745-2473 (print). An uncertainty comparable to that from the modelling of the signal and background components is induced by the limited sizes of calibration samples. A precision measurement of the mass of the top quark | Nature According to the Standard Model of particle physics, particles such as beauty quarks should decay into either muons or electrons in equal measure. The significance of this discrepancy is 3.1standard deviations, giving evidence for the violation of lepton universality in these decays. Wills Physics Laboratory, University of Bristol, Bristol, UK, M. Adinolfi,S. Bhasin,P. Camargo Magalhaes,M. G. Chapman,R. Lane,S. Maddrell-Mander,L. R. Madhan Mohan,A. M. Marshall,P. Naik,D. P. OHanlon,K. Petridis,G. J. Pomery,J. H. Rademacker,J. J. Velthuis,R. Wang,B. D. C. Westhenry&M. Whitehead, Universit Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, MI, France, H. Afsharnia,Z. Ajaltouni,E. Cogneras,O. Deschamps,R. Lefvre,J. Maratas,S. Monteil,P. Perret,D. Popov,H. Sazak,L. Soares Lavra&V. Tisserand, C. A. Aidala,D. S. Fitzgerald,S. H. Lee,K. R. Mattioli,C. Nunez,J. D. Roth&D. M. Shangase, S. Aiola,J. Fu,P. Gandini,L. Henry,D. Marangotto,A. Merli,N. Neri,M. Petruzzo&E. Spadaro Norella, University of Cincinnati, Cincinnati, OH, USA, S. Akar,P. Ilten,B. Meadows,C. Pappenheimer,M. D. Sokoloff,M. Stahl&D. Vieira, Fakultt Physik, Technische Universitt Dortmund, Dortmund, Germany, J. Albrecht,A. Battig,M. Becker,M. S. Bieker,J. 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. LHCb explores the beauty of lepton universality - phys.org Uncertainties on the data points are statistical only and represent one standard deviation. Left: the SM contribution involves the electroweak bosons ,W+ and Z0, and the up-type quarks , \(\bar{c}\) and \(\bar{t}\). LHCb collaboration et al. Int. Nucl. Phys. For the non-resonant B+K+e+e decays, the systematic uncertainties are dominated by the modelling of the signal and background components used in the fit. Test of lepton universality with beauty baryons, RpK Today at the Rencontres de Moriond EW conference, the LHCb Collaboration presented an updated measurement of the ratio R K, an important test of a principle of the Standard Model of particle physics known as " lepton universality ", which states that the Standard Model treats the three charged leptons (electrons, muons and . Energy Phys. 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. For RK the LHCb measurements are in the range 1.1On Drell-Yan production of scalar leptoquarks coupling to heavy-quark The particles are required to originate from a common vertex, displaced from the protonproton interaction point, with good vertex-fit quality. Lees, J. P. et al. 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. 199, 86101 (2016). Lees, J. P. et al. Thank you for visiting nature.com. Aubert, B. et al. Breiman, L., Friedman, J. H., Olshen, R. A., & Stone C. J. Rev. (2016). J. Sifting through proton . Isidori, G., Nabeebaccus, S. & Zwicky, R. QED corrections in \(\overline{B}\to \overline{K}{{{{\rm{\ell }}}}}^{+}{{{{\rm{\ell }}}}}^{-}\) at the double-differential level. 18 (2022) 277 [ arXiv:2103.11769] [ INSPIRE ]. What our students say. J. High Energy Phys. The muon BDT classifier has similar performance. This causes misidentification backgrounds to populate a range of K masses but only a peak in the Ke mass. J. The efficiency of the non-resonant B+K+e+e decay therefore needs to be known only relative to that of the resonant B+J/(e+e)K+ decay, rather than relative to the B+K++ decay. The ratio of branching fractions, RH (refs. Capdevila, B., Descotes-Genon, S., Matias, J. 2020, 083C01 (2020). New physics in bs+ confronts new data on lepton universality. Test of lepton universality in beauty-quark decays, arXiv:2103.1176 . The y-axis in each figure shows the number of candidates in an interval of the indicated width. Ciuchini, M. et al. 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. The consistency of this ratio with unity demonstrates control of the efficiencies well in excess of that needed for the determination of RK. Different types of charged particles are distinguished using information from two ring-imaging Cherenkov detectors, a calorimeter and a muon system76. The techniques used to identify the different particles and to form B+ candidates are described in Methods. Lepton avour universality tests in electroweak penguin decays at LHCb Phys. This principle states that the SM treats the three charged leptons (electrons, muons and taus) identically . LHCb topological trigger reoptimization. Alok, A. K., Dighe, A., Gangal, S. & Kumar, D. Continuing search for new physics in bs decays: two operators at a time. Measurements of the angular distributions in the decays BK(*)+ at CDF. Phys. A weighted least-squares method is then employed to find the precise vertex position. 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. Simulated events are weighted to correct for the imperfect modelling using control channels. (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. Test of lepton universality in beauty-quark decays - Academia.edu 10, 075 (2016). Search for lepton-universality violation in B+K++ decays. The 3,85070 B+K++ decay candidates that are observed are used to compute the B+K++ branching fraction as a function of q2. The bias is found to be 1% of the statistical precision and thus negligible with respect to other sources of systematic uncertainty. A. Lett. We are indebted to the communities behind the multiple open-source software packages on which we depend. Phys.) High Energy Phys. The corresponding significance in terms of standard deviations is computed using the inverse Gaussian cumulative distribution function for a one-sided conversion. Phys. Test of lepton universality in beauty-quark decays - Nature The 1.9% uncertainty on the B+J/K+ branching fraction2 gives rise to the dominant systematic uncertainty. Phys. D 93, 052015 (2016). J. Instrum. Measurement of an excess of \(\overline{B}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }\) decays and implications for charged Higgs bosons. Background originates from particles selected from multiple hadron decays, referred to as combinatorial background, and from specific decays of B hadrons. 2017, 055 (2017). Electrons are identified by matching tracks to particle showers in the electromagnetic calorimeter (ECAL) and using the ratio of the energy detected in the ECAL to the momentum measured by the tracking system. The ATLAS collaboration et al. & Virto, J. Test of lepton universality in beauty-quark decays . Jan 2019; PHYS REV LETT; High Energy Phys. Likhomanenko, T. et al. The k-folding technique is used in the training and testing81. Rev. Evidence for an excess of \(\overline{B}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }\) decays. A multivariate algorithm is used for the identification of displaced vertices consistent with the decay of a B hadron77,78. These decays all proceed via the same \(\overline{b}\to \overline{s}\) quark transition, and the results have therefore further increased interest in measurements of angular observables24,25,26,27,28,29,30,31,32,33,34 and branching fractions35,36,37,38 of decays mediated by \(\overline{b}\to \overline{s}{\mu }^{+}{\mu }^{-}\) transitions. Yields of the nonresonant and resonant decay modes obtained from the fits to the data. Distribution of the invariant mass m(K+e+e) for B+K+e+e candidates. 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. Prog. Phys. PDF Beauty quarks test lepton universality - cds.cern.ch (Bottom) the single ratio rJ/ relative to its average value \(< {r}_{J/\psi } >\) as a function of these variables. 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. However, the strong force does not couple directly to leptons, hence its effect on the B+K++ and B+K+e+e decays is identical. A breaking of lepton universality would require an extension of the gauge structure of the SM that gives rise to the known fundamental forces. 5, together with the spectra expected for the resonant and non-resonant decays. Descotes-Genon, S., Hofer, L., Matias, J. Lett. Rev. Lyon, J., & Zwicky, R. Resonances gone topsy turvythe charm of QCD or new physics in bs+? $$\overline B_{\mathrm{s}}^0$$ https://doi.org/10.1038/s41567-021-01478-8, DOI: https://doi.org/10.1038/s41567-021-01478-8. Energy Phys. The simulated data used in this analysis are produced using the software described in refs. Global analysis of bs anomalies. J. & Virto, J. Ghosh, D., Nardecchia, M. & Renner, S. A. 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. The experiment is designed to study decays of particles containing a beauty quark, a fundamental particle that has roughly four times the mass of the proton. 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 Serra, N., Silva Coutinho, R. & van Dyk, D. Measuring the breaking of lepton flavor universality in BK*+. 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. PDF Test of lepton universality in beauty-quark decays - DiVA portal Hiller, G. & Krger, F. More model-independent analysis of bs processes. Belyaev, I. et al. Phys. Beaujean, F., Bobeth, C. & van Dyk, D. Comprehensive Bayesian analysis of rare (semi)leptonic and radiative B decays. New result from the LHCb experiment challenges leading theory in physics New tests of lepton universality show the same pattern as deviations Geng, L.-S. et al. LHCb collaboration et al. High. Bhupal Dev and A. Soni, {R}_ {D^ {\left (\ast \right)}} anomaly: A possible hint for natural supersymmetry with R-parity violation, Phys. The green and purple components correspond to candidates with \({q}_{{{{\rm{t}}}}rue}^{2} > 6.0\) GeV 2/c4 and \({q}_{{{{\rm{t}}}}rue}^{2} < 1.1\) GeV 2/c4, respectively. The mass-shape parameters are derived from the calibrated simulation. 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. Measurement of the ratio of branching fractions \({{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\tau }^{+}{\nu }_{\tau })/{{{\mathcal{B}}}}{{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu })\). The departure of the profile likelihood shown in Extended Data Fig. Comput. the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in The fit projection is superimposed, with dotted lines describing the signal contribution and solid areas representing each of the background components described in the text and listed in the legend. D 69, 074020 (2004). 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. Wei J.-T. et al. D 2, 12851292 (1970). Use the Previous and Next buttons to navigate the slides or the slide controller buttons at the end to navigate through each slide. 18, 277282 (2022). 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). The PVs are reconstructed by searching for space points where an accumulation of track trajectories is observed. Phys. CERN https://cds.cern.ch/record/2636441 (2019). Physics - A Challenge to Lepton Universality 4 has been added to the HEPData platform at https://www.hepdata.net/record/ins1852846?version=1.

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