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. Zhu, L. Capriotti,A. Carbone,A. Falabella,F. Ferrari,D. Galli,S. Maccolini,D. Manuzzi,U. Marconi,C. Patrignani,S. Perazzini,M. Soares,V. Vagnoni,G. Valenti&S. Zucchelli, L. Capriotti,A. Carbone,F. Ferrari,D. Galli,S. Maccolini,D. Manuzzi,C. Patrignani&S. Zucchelli, INFN Sezione di Roma Tor Vergata, Roma, Italy, Institute Of High Energy Physics (IHEP), Beijing, China, I. Carli,S. Chen,Y. Li,Y. Li,S. Liu,Y. Lu,L. Ma,M. Tobin,J. Wang&Q. Zou, Univ. The pT spectrum of the B+J/K+ decays is similar to that of the corresponding B+K++ decays such that the measurement of rJ/ tests the kinematic region relevant for the RK measurement. 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. Eur. 2020, 40 (2020). The systematic uncertainty (Methods) from the choice of signal and background mass-shape models in the fits is estimated by fitting pseudo-experiments with alternative models that still describe the data well. 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. Rev. High. High. Khodjamirian, A., Mannel, T., Pivovarov, A. Explore our virtual experience However, a bremsstrahlung photon emitted upstream of the magnet will deposit energy in a different part of the ECAL than the electron, which is deflected in the magnetic field. High Energy Phys. This uncertainty includes both statistical and systematic effects, where the latter dominate. 103, 171801 (2009). The trigger response is corrected using weights applied to simulation as a function of variables relevant to the trigger algorithms. 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. Wehle, S. et al. The SM is unable to explain cosmological observations of the dominance of matter over antimatter, the apparent dark matter content of the Universe, or the patterns seen in the interaction strengths of the particles. 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. In the electron case, a 40MeV c2 window around the D0 mass is used to reject candidates where the veto is applied without the bremsstrahlung recovery, that is, on the basis of only the measured track momenta. In addition, rJ/ is computed in two-dimensional intervals of reconstructed quantities (Extended Data Fig. J. 2017, 36 (2017). B. Zonneveld, Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania, L. Cojocariu,A. Ene,L. Giubega,A. Grecu,F. Maciuc,V. Placinta&M. Straticiuc, L. Congedo,M. De Serio,R. A. Fini,A. Palano,M. Pappagallo,A. Pastore&S. Simone, L. Congedo,M. De Serio,M. Pappagallo&S. Simone, Los Alamos National Laboratory (LANL), Los Alamos, NM, USA, J. Crkovsk,C. L. Da Silva,C. T. Dean,J. M. Durham,E. Epple&G. J. Kunde, Van Swinderen Institute, University of Groningen, Groningen, Netherlands, K. De Bruyn,C. J. G. Onderwater&M. van Veghel, Universiteit Maastricht, Maastricht, Netherlands, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Krakw, Poland, A. Dendek,M. Firlej,T. Fiutowski,M. Idzik,P. Kopciewicz,W. Krupa,O. Madejczyk,M. W. Majewski,J. Moron,A. Oblakowska-Mucha,B. Rachwal,J. Ryzka,K. Swientek&T. Szumlak, F. Dettori,C. Giugliano,G. Manca,R. Oldeman&B. Saitta, Eotvos Lorand University, Budapest, Hungary, Institute for Nuclear Research of the National Academy of Sciences (KINR), Kyiv, Ukraine, V. Dobishuk,S. Koliiev,I. Kostiuk,O. Kot&V. Pugatch, School of Physics, University College Dublin, Dublin, Ireland, A. M. Donohoe,L. Mcconnell,R. McNulty,N. V. Raab&C. B. Provided by the Springer Nature SharedIt content-sharing initiative, Rendiconti Lincei. Rev. Aaij, R. et al. Theor. 3, S08005 (2008). Since the J/+ branching fractions are known to respect lepton universality to within 0.4% (refs. Alguer, M. et al. 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. Differential branching fractions and isospin asymmetries of BK(*)+ decays. 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). Altmannshofer, W. & Yavin, I. Davidson, N., Przedzinski, T. & Was, Z. The energy of any such deposit is added to the electron energy that is derived from the measurements made in the tracker. where the first uncertainty is statistical and the second systematic. 6). Correlations between different categories of selected events and data-taking periods are taken into account in these constraints. Phys. Rev. Publishers note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. The correlation is evaluated using a bootstrapping method to recompute the yields and efficiencies many times with different subsets of the data. Capdevila, B., Descotes-Genon, S., Matias, J. Such studies can help to explain the matter-antimatter asymmetryof the Universe. Energy Phys. 178, 852867 (2008). Slider with three articles shown per slide. Phys. Bobeth, C., Chrzaszcz, M., van Dyk, D. & Virto, J. Recent evidence of a possible fifth force of nature For each of the classifiers, a requirement is placed on the output variable to maximize the predicted significance of the non-resonant signal yield. Rev. 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. An example distribution, with rJ/ determined as a function of B+ momentum component transverse to the beam direction, pT, is shown in Fig. This double ratio is expected to be close to unity2 and is determined to be 0.9970.011, where the uncertainty includes both statistical and systematic effects, the former of which dominates. 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. LHCb collaboration et al. 118, 031802 (2017). Although this may not be happening, it suggests a new study by the LHCb Collaboration at CERN. Measurement of angular asymmetries in the decays BK*+. Article Savoie Mont Blanc, CNRS, IN2P3-LAPP, Annecy, France, M. Chefdeville,D. Decamp,A. G. Downes,Ph. In the electron minimum pT spectra, the structure at 2800 MeV/c is related to the trigger threshold. MathSciNet Left: the SM contribution involves the electroweak bosons ,W+ and Z0, and the up-type quarks , \(\bar{c}\) and \(\bar{t}\). The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Article The BDT output is not strongly correlated with q2, and the same classifiers are used to select the respective resonant decays. This causes misidentification backgrounds to populate a range of K masses but only a peak in the Ke mass. Distribution of the invariant mass mJ/(K++) for resonant candidates in the (left) sample previously analysed11 and (right) the new data sample. Test of lepton universality in beauty-quark decays - NASA/ADS 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. 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. The B+ production kinematics are corrected using B+J/(+)K+ events. This resolution scaling changes the migration of candidates into the q2 region of interest by less than 1%. This principle states that the SM treats the three charged leptons (electrons, muons and taus) identically . 4 has been added to the HEPData platform at https://www.hepdata.net/record/ins1852846?version=1. The collider accelerates two counter-rotating beams of protons, guided by superconducting magnets located around a 27km circular tunnel, and brings them into collision at four interaction points that house large detectors. Nature 546, 227 . To take into account the correlation between the selection efficiencies, the m(K+e+e) and m(K++) distributions of non-resonant candidates in each of the different trigger categories and data-taking periods are fitted simultaneously, with a common value of RK. 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. The Large Hadron Collider beauty collaboration reports a test of lepton flavour universality in decays of bottom mesons into strange mesons and a charged lepton pair, finding evidence of a violation of this principle postulated in the standard model. 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. 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. Martnez Santos, D. & Dupertuis, F. Mass distributions marginalized over per-event errors. Commun. This is known as lepton universality. Fan,J. Measurement of \({{{\mathcal{R}}}}(D)\) and \({{{\mathcal{R}}}}({D}^{* })\) with a semileptonic tagging method. (Right, with linear y-scale) the mass is computed only from the track information. Phys. Eur. Test of lepton universality in beauty-quark decays . Lees, J. P. et al. The theory predicts that the di erent charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Beauty quarks test lepton universality - CERN Courier 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 102, 055001 (2020). Improved lepton universality measurements show agreement with the You are using a browser version with limited support for CSS. The calibration samples consist of D*+D0(K+)+, J/+ and B+J/(e+e)K+ decays, from which kaons, muons and electrons, respectively, can be selected without applying particle identification requirements. universality in B-meson decays. The major challenge of the measurement is then correcting for the efficiency of the selection requirements used to isolate signal candidates and reduce background. In addition to B+J/K+ decays, clear signals are observed from B+(2S)K+ decays. 14, P11023 (2019). The calibrated simulation is used subsequently to obtain the m(K++) mass shape and relative fractions of these background components. Measurement of the ratio of branching fractions \({{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\tau }^{+}{\nu }_{\tau })/{{{\mathcal{B}}}}{{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu })\). D 96 (2017) 095010 [ arXiv:1704.06659] [ INSPIRE ]. Since the associated data storage and analysis costs would be prohibitive, the experiment does not record all collisions. ISSN 1745-2473 (print). Beating the hold-out: bounds for K-fold and progressive cross-validation. The B+ momentum vector is required to be aligned with the vector connecting one of the PVs in the event (below referred to as the associated PV) and the B+ decay vertex. Instrum. 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. 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. Resolution effects similarly motivate the choice of non-resonant q2 regions, with a lower limit that excludes contributions from -meson decays and an upper limit that reduces the tail from B+J/(e+e)K+ decays. Precision measurements of \({{{\mathcal{B}}}}[\psi (3686)\to \ \ {\pi }^{+}{\pi }^{-}J/\psi ]\) and \({{{\mathcal{B}}}}[J/\psi \to \ \ {\ell }^{+}{\ell }^{-}]\). Update of lepton universality test measurement RK - CERN Lett. 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. The techniques used to identify the different particles and to form B+ candidates are described in Methods. (Bottom) the single ratio rJ/ relative to its average value \(< {r}_{J/\psi } >\) as a function of these variables. 2. Similarly, computations of the rJ/ ratio in bins of two kinematic variables also do not show any trend and are consistent with the systematic uncertainties assigned on the RK measurement. The hierarchical effect needed to explain the existing \(\overline{b}\to \overline{s}{\ell }^{+}{\ell }^{-}\) and \(\overline{b}\to \overline{c}{\ell }^{+}{\nu }_{\ell }\) data, with the largest effects observed in tau modes, then muon modes and little or no effects in electron modes, suggests that studies of \(\overline{b}\to \overline{s}{\tau }^{+}{\tau }^{-}\) transitions are also of great interest69,70. Aaij, R. et al. The LHCb collaboration et al. The y-axis in each figure shows the number of candidates in an interval of the indicated width. Huber, P. J. in Robust Estimation of a Location Parameter (eds Kotz S. & Johnson N. L.) 492518 (Springer, 1992). Extended Data Fig. & Rusov, A. V. BsK and B(s)(K)+ decays at large recoil and CKM matrix elements. Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands, R. Aaij,J. S. Butter,K. Carvalho Akiba,S. Ferreres Sole,E. Gabriel,R. E. Geertsema,L. M. Greeven,K. Heijhoff,W. Hulsbergen,D. Hynds,E. Jans,S. Klaver,P. Koppenburg,I. Kostiuk,H. S. Kuindersma,M. Lucio Martinez,V. Lukashenko,A. Mauri,M. Merk,A. Pellegrino,C. Sanchez Gras,M. Schubiger,A. Snoch,N. Tuning,A. Usachov,M. van Beuzekom&M. Veronesi, Physik-Institut, Universitt Zrich, Zrich, Switzerland, C. Abelln Beteta,M. Atzeni,R. Bernet,C. Betancourt,Ia. Ser. This is the most precise measurement of this ratio to date and is compatible with the SM prediction with a P value of 0.10%. 3 Resonant candidates invariant mass distributions. The LHCb Collaboration, Test of lepton universality in beauty-quark decays, Nature Physics 18, (2022) 277-282. Similarly, the differing q2 resolution between data and simulation, which alters estimates of the q2 migration, has negligible impact on the result. 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. LHCb explores the beauty of lepton universality | CERN Descotes-Genon, S., Hofer, L., Matias, J. For the non-resonant muon mode and for each of the three different trigger categories of the non-resonant electron mode, a single BDT classifier is trained for the 7 and 8TeV data, and an additional classifier is trained for the 13TeV data.