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. High. The J/ meson consists of a charm quark and antiquark, \(c\overline{c}\), and is produced resonantly at q2=9.59GeV2c4. Uncertainties on the data points are statistical only and represent one standard deviation. The ATLAS and CMS experiments may also be able to contribute73,74. 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. Chat with our students. Lett. 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. Eur. Phys. The LHCbdetector at the LHC. Nucl. Phys. Google Scholar. 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. The signal is represented by the orange shaded region and the various cascade background contributions by red, dark blue and light blue shaded regions. Ser. The effect on RK is at the 1% level. 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. Test of lepton universality in beauty-quark decays. New tests of lepton universality show the same pattern as deviations Phys. Yields of the nonresonant and resonant decay modes obtained from the fits to the data. Test of Lepton Flavour Universality using a measurement of R(D*) with Conf. The region to the left of the vertical dashed line is rejected. Altmannshofer, W. & Yavin, I. Search for lepton-universality violation in B+K++ decays. Explore our virtual experience J. 126, 161802 (2021). Extended Data Table 2 Yields of the nonresonant and resonant decay modes. In the latter two decays, the kaon is misidentified as a lepton and the lepton (of the same electric charge) as a kaon. Hirose, S. et al. 1. W. Altmannshofer, P.S. The major challenge of the measurement is then correcting for the efficiency of the selection requirements used to isolate signal candidates and reduce background. High Energy Phys. Rev. B. Rodrigues,O. Schneider,S. Schulte,L. Shchutska,P. Stefko,M. E. Stramaglia,M. T. Tran,C. Trippl,A. Tully,M. Van Dijk,M. Vieites Diaz&E. Zaffaroni, Department of Physics, University of Warwick, Coventry, UK, J. J. Particle Physics (4th ed. Such background is reduced to a negligible level by particle identification criteria. Eur. J. CMS collaboration Angular analysis of the decay B0K*0+ from pp collisions at \(\sqrt{s}=8\) TeV. Rev. MathSciNet 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. The value of RK is a fit parameter, which is related to the signal yields and efficiencies according to. This is known as lepton universality. The energy of any such deposit is added to the electron energy that is derived from the measurements made in the tracker. LHCb software used to process the data analysed in this paper is available at https://gitlab.cern.ch/lhcb. Exp. 08, 098 (2016). where N(X) indicates the yield of decay mode X and (X) is the efficiency for selecting decay mode X. 125, 011802 (2020). Wehle, S. et al. A challenge to lepton universality in B-meson decays | Nature The B+ production kinematics are corrected using B+J/(+)K+ events. 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. The LHCb collaboration et al. High. Lyon, J., & Zwicky, R. Resonances gone topsy turvythe charm of QCD or new physics in bs+? D 103, 015030 (2021). Evidence for an excess of \(\overline{B}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }\) decays. Differential branching fraction and angular analysis of the decay B0K+I+in the \({K}_{0,2}^{* }{(1430)}^{0}\) region. Phys. Phys. Each top (antitop) quark decays almost immediately into a bottom b ( b) quark and a W+ ( W -) boson, and we have reexamined those events in which one of the W bosons decays into a charged. 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. 115, 111803 (2015); erratum 115, 159901 (2015). Phys. An example distribution, with rJ/ determined as a function of B+ momentum component transverse to the beam direction, pT, is shown in Fig. The standard model (SM) of particle physics provides precise predictions for the properties and interactions of fundamental particles, which have been confirmed by numerous experiments since the inception of the model in the 1960s. 11,12, the P value is computed by integrating the posterior probability density function for RK, having folded in the theory uncertainty on the SM prediction, for RK values larger than the SM expectation. Rev. Background from decays with a photon converted into an e+e pair are also negligible due to the q2 selection. LHCb collaboration, Test of lepton universality in beauty-quark decays, Nature Phys. s The decays involve the transformation of a beauty quark into a strange quark (bs) plus a lepton pair ( + - or e + e - ), a process that is highly suppressed in the Standard Model but which could be affected by the existence of new particles, whose masses could be too high to be produced directly at the Large Hadron Collider. 2010, 89 (2010). Energy 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, + . For RK the LHCb measurements are in the range 1.1New tests of lepton universality show the same pattern as deviations Lett. Slider with three articles shown per slide. 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. Test of lepton flavour universality in beauty-quark decays 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. Phys. The results are consistent between the different data-taking periods and with previous LHCbmeasurements37. Exp. The value of q2 is calculated using only the lepton momenta, without imposing any constraint on the m(K++) mass. To avoid unconscious bias, the analysis procedure was developed and the cross-checks described below performed before the result for RK was examined. 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. The particle identification performance is calibrated using data, where the species of particles in the final state can be unambiguously determined purely on the basis of the kinematics. Energy Phys. The mass distributions are shown in Extended Data Fig. 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 In the fit for RK, these yields and the efficiencies are incorporated as Gaussian-constraint terms. The B+J/(+)K+ events selected from the data have also been used to demonstrate control of the electron track reconstruction efficiency at the percent level90. The PVs are reconstructed by searching for space points where an accumulation of track trajectories is observed. Combining the uncertainties gives \({R}_{K}=0.84{6}_{-\ 0.041}^{+\ 0.044}\). Uncertainties on the data points are statistical only and represent one standard deviation, calculated assuming Poisson-distributed entries. Methods A 764, 150155 (2014). Test of lepton flavor universality by the measurement of the B0D*+ branching fraction using three-prong decays. Wei J.-T. et al. Even though the non-resonant and resonant samples are mutually exclusive as a function of q2, there is significant overlap between them in the quantities on which the efficiency depends, such as the laboratory-frame momenta of the final-state particles or the opening angle between the two leptons. 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. D 73, 092001 (2006). 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. A comparison with previous measurements is shown in Fig. Due to the small masses of both electrons and muons compared with that of b quarks, this ratio is predicted to be close to unity, except where the value of the dilepton invariant mass-squared (q2) significantly restricts the phase space available to form the two leptons. In all fits, the combinatorial background is modelled with an exponential function with a freely varying yield and shape. De Aguiar Francisco,S. De Capua,D. Dutta,C. Fitzpatrick,E. Gersabeck,M. Gersabeck,L. Grillo,M. Hilton,G. Lafferty,J. J. 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. Linear (top) and logarithmic (bottom) scales are shown. Uncertainties on the data points are statistical only and represent one standard deviation, calculated assuming Poisson-distributed entries. Measurement of \({{{\mathcal{R}}}}(D)\) and \({{{\mathcal{R}}}}({D}^{* })\) with a semileptonic tagging method. In addition to B+J/K+ decays, clear signals are observed from B+(2S)K+ decays. Article The fit projections for the m(K++) and mJ/(K++) distributions are shown in Fig. For the resonant modes, the results from independent fits to each period/category are shown. D 69, 074020 (2004). Tension with the SM is also seen in the combination of several ratios that test lepton universality in \(\overline{b}\to \overline{c}{\ell }^{+}{\nu }_{\ell }\) transitions55,56,57,58,59,60,61,62,63. Article J. LHCb explores the beauty of lepton universality | CERN Provided by the Springer Nature SharedIt content-sharing initiative, Rendiconti Lincei. Beating the hold-out: bounds for K-fold and progressive cross-validation. 10, 075 (2016). 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. C 79, 714 (2019); addendum 80, 511 (2020). Sifting through proton . The fit projection is superimposed, with a black dotted line describing the signal contribution and solid areas representing each of the background components described in the text and listed in the legend. Phys. Phys. CERN experiment found that beauty quarks not behaving in the way they 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. Aaij, R. et al. Eur. Phys. Classification and Regression Trees (Wadsworth, 1984). 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. Lett. Lange, D. J. Review of particle physics. 3, S08005 (2008). Internet Explorer). 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. Simulated events are weighted to correct for the imperfect modelling using control channels. 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. ADS The CMS collaboration Measurement of angular parameters from the decay B0K*0+ in proton-proton collisions at \(\sqrt{s}=\) 8 TeV. 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 profile likelihood is given in Methods. This effect is accounted for using simulation (Extended Data Figs. Rev. Davidson, N., Przedzinski, T. & Was, Z. Ablikim, M. et al. 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. B. Coelho,F. Desse,F. Machefert,E. M. Niel,P. Robbe,M. H. Schune&G. Wormser, L. Anderlini,A. Bizzeti,G. Graziani,S. Mariani,G. Passaleva&M. Veltri, M. Andreotti,W. Baldini,C. Bozzi,R. Calabrese,M. Fiorini,E. Franzoso,C. Giugliano,P. Griffith,M. Guarise,S. Kotriakhova,E. Luppi,A. Minotti,L. Minzoni,I. Neri,L. L. Pappalardo,B. Passalacqua,B. G. Siddi,I. Slazyk,L. Tomassetti&S. Vecchi, Physikalisches Institut, Ruprecht-Karls-Universitt Heidelberg, Heidelberg, Germany, F. Archilli,S. Bachmann,D. Berninghoff,M. Borsato,G. Frau,D. Gerick,J. P. Grabowski,P. A. Gnther,X. Han,S. Hansmann-Menzemer,J. Hu,R. Kopecna,B. Leverington,P. Li,H. Malygina,J.
Nordstrom Benefits Portal, Golden Steer Happy Hour Menu, Medicare Gpo Box 9822 In Your Capital City, Articles T