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J. The theory predicts that the di erent charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. The ratio of branching fractions, RH (refs. The measurements are of processes in which a beauty meson transforms into a strange meson with . J. On Drell-Yan production of scalar leptoquarks coupling to heavy-quark 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. 178, 852867 (2008). This uncertainty includes both statistical and systematic effects, where the latter dominate. Update of lepton universality test measurement RK - CERN Simulated events are used to derive the two ratios of efficiencies needed to form RK using equation (2). Int. 2014, 125 (2014). Phys. Scienze Fisiche e Naturali (2023), Nature Physics (Nat. Capdevila, B., Descotes-Genon, S., Hofer, L. & Matias, J. Hadronic uncertainties in BK*+: a state-of-the-art analysis. 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. 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. In the resonant-mode distributions, some fit components are too small to be visible. Test of lepton universality with B0K*0+ decays. The y-axis in each figure shows the number of candidates in an interval of the indicated width. Test of lepton universality in beauty-quark decays - Nature The region between the dashed vertical lines is rejected. Handling of the generation of primary events in Gauss, the LHCb simulation framework. Confirmation of any effect beyond the SM will clearly require independent evidence from a wide range of sources. J. Extended Data Fig. Energy Phys. Capdevila, B., Descotes-Genon, S., Matias, J. The decays used in this analysis to study lepton universality are extremely rare. Eur. 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. J. A weighted least-squares method is then employed to find the precise vertex position. The distribution of this ratio as a function of the angle between the leptons and the minimum pT of the leptons is shown in Extended Data Fig. Similarly, the differing q2 resolution between data and simulation, which alters estimates of the q2 migration, has negligible impact on the result. Phys. LHCb collaboration et al. C 82, 7 (2022). 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. 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. High Energy Phys. The mass distributions are shown in Extended Data Fig. 108, 081807 (2012). The double ratio of branching fractions, R(2S), defined by. Similarly, the variations seen in rJ/ as a function of all other reconstructed quantities examined are compatible with the systematic uncertainties assigned. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. Glashow, S. L., Iliopoulos, J. Test of lepton universality using B 0 K S 0 l + l- and B + K* + l + l- decays.. 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. The yields in the two B+K++ and two B+J/(+)K+ decay modes are determined by performing unbinned extended maximum-likelihood fits to these distributions (Methods). C 74, 2897 (2014); erratum 74, 3179 (2014). J. EPJ Web Conf. High. 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. Phys. Rev. All contributing authors, as listed at the end of the manuscript, have contributed to the publication, being variously involved in the design and construction of the detector, writing software, calibrating sub-systems, operating the detector, acquiring data and analysing the processed data. The B+K++ and B+J/(+)K+ candidates must be triggered by one of the muons, whereas B+K+e+e and B+J/(e+e)K+ candidates must be triggered in one of three ways: by either one of the electrons, by the kaon from the B+ decay or by other particles in the event that are not decay products of the B+ candidate. When compared with the 20% shift that these corrections induce in the measurement of rJ/, this demonstrates the robustness of the double-ratio method in suppressing systematic biases that affect the resonant and non-resonant decay modes similarly. 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. Sign up for the Nature Briefing newsletter what matters in science, free to your inbox daily. The results supersede those of the previous LHCb analysis. Phys. 4 from a normal distribution stems from the definition of RK. These are included in the fit to RK by allowing the relative efficiency to vary within Gaussian constraints. Phys. Uncertainties on the data points are statistical only and represent one standard deviation. Whenever B+J/(+)K+ events are used to correct the simulation, the correlations between calibration and measurement samples are taken into account in the results and cross-checks presented in this paper. 12, 104 (2020). The ratio between the branching fractions of these decays is therefore predicted with \({{{\mathcal{O}}}}(1 \%)\) precision3,4,5,6,7,8. The profile likelihood for the fit to the non-resonant decays is shown in Extended Data Fig. Rev. J. 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. J. Measurement of the ratio of branching fractions \({{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\tau }^{+}{\nu }_{\tau })/{{{\mathcal{B}}}}{{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu })\). Phys. Test of lepton universality in beauty-quark decays LHCb collaboration Nature Physics 18 , 277-282 ( 2022) Cite this article 8068 Accesses 76 Citations 29 Altmetric Metrics Abstract. Lett. The electron and muon veto cuts differ given the relative helicity suppression of ++ decays. High Energy Phys. 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. The residual contribution from such decays is considered as a source of systematic uncertainty. Such a modification can be realized in new physics models with an additional heavy neutral boson or with leptoquarks. Angular analysis of \({B}_{d}^{0}\to {K}^{* }{\mu }^{+}{\mu }^{-}\) decays in pp collisions at \(\sqrt{s}=8\) TeV with the ATLAS detector. This symmetry is called lepton avour universality (LFU) and is established in for example /0! 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 departure of the profile likelihood shown in Extended Data Fig. Since the J/+ branching fractions are known to respect lepton universality to within 0.4% (refs. Differential branching fraction and angular analysis of the decay B0K+I+in the \({K}_{0,2}^{* }{(1430)}^{0}\) region. 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. Uncertainties on the data points are statistical only and represent one standard deviation, calculated assuming Poisson-distributed entries. The B+ production kinematics are corrected using B+J/(+)K+ events. 122, 191801 (2019). Aebischer, J. et al. 2 (Extended Data Fig. In addition to affecting the decay rates, new physics can also alter how the decay products are distributed in phase space. Bobeth, C., Hiller, G. & Piranishvili, G. Angular distributions of \(\bar{B}\to K\bar{\ell }\ell\) decays. The orange shaded area corresponds to B+K+e+e candidates with true q2 (\({q}_{{{{\rm{t}}}}rue}^{2}\)) outside the [1.1,6.0] GeV 2/c4 interval. D 97, 012004 (2018). Test of lepton universality in beauty-quark decays - arXiv Vanity Global analysis of bs anomalies. The fit projections are 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. In all fits, the combinatorial background is modelled with an exponential function with a freely varying yield and shape. Methods A 764, 150155 (2014). Lett. Emerging patterns of new physics with and without lepton flavour universal contributions. J. & Virto, J. LHCb experiment - Wikipedia Lett. Nucl. Test of lepton universality in beauty-quark decays Conf. LHCb collaboration LHCb detector performance. J. Instrum. Energy Phys. Intriguing New Results from CERN Challenge Standard Model of Particle 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. Following the procedure described in refs. Hurth, T., Mahmoudi, F. & Neshatpour, S. Implications of the new LHCb angular analysis of BK*+: hadronic effects or new physics? 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. Phys. Prog. Similar considerations apply to decays with other B hadrons, BH+ and BHe+e, where B= B+, B0, \({B}_{s}^{0}\) or \({\Lambda }_{b}^{0}\), and H can be, for example, an excited kaon, K*0, or a combination of particles such as a proton and charged kaon, pK. (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. J. Phys. Yields of the nonresonant and resonant decay modes obtained from the fits to the data. Kou, E. et al. The analysis uses beauty mesons produced in proton-proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 $\mathrm{fb}^{-1}$.. {6\ }_{-\ 1.4}^{+\ 1.5}\ \pm 1.3)\times 1{0}^{-9}\ {c}^{4}\,{{{{\rm{GeV}}}}}^{-2}\ .\end{array}$$, \(\overline{b}\to \overline{s}{\ell }^{+}{\ell }^{-}\), \(\overline{b}\to \overline{s}{\tau }^{+}{\tau }^{-}\), \(B\to {H}_{c}(\to {K}^{+}{\ell }^{-}{\overline{\nu }}_{\ell }X){\ell }^{+}{\nu }_{\ell }Y\), $$\begin{array}{rcl}{R}_{K}&=&\frac{N({B}^{+}\to {K}^{+}{\mu }^{+}{\mu }^{-})}{\varepsilon ({B}^{+}\to {K}^{+}{\mu }^{+}{\mu }^{-})}\cdot \frac{\varepsilon ({B}^{+}\to {K}^{+}{e}^{+}{e}^{-})}{N({B}^{+}\to {K}^{+}{e}^{+}{e}^{-})}\\ &&\times \frac{\varepsilon ({B}^{+}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){K}^{+})}{N({B}^{+}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){K}^{+})}\cdot \frac{N({B}^{+}\to J/\psi (\to {e}^{+}{e}^{-}){K}^{+})}{\varepsilon ({B}^{+}\to J/\psi (\to {e}^{+}{e}^{-}){K}^{+})}\ ,\end{array}$$, \(\overline{B}\to \overline{K}{{{{\rm{\ell }}}}}^{+}{{{{\rm{\ell }}}}}^{-}\), \({\Lambda }_{b}^{0}\to p{K}^{-}{\ell }^{+}{\ell }^{-}\), \({B}_{d}^{0}\to {K}^{* }{\mu }^{+}{\mu }^{-}\), \({B}_{s}^{0}\to \phi {\mu }^{+}{\mu }^{-}\), \({\Lambda }_{b}^{0}\to \Lambda {\mu }^{+}{\mu }^{-}\), \({B}_{s}^{0}\to \ \ \phi {\mu }^{+}{\mu }^{-}\), \(\overline{B}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }\), \({{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\tau }^{+}{\nu }_{\tau })/{{{\mathcal{B}}}}{{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu })\), \({\overline{B}}^{0}\to {D}^{* +}{\tau }^{-}{\overline{\nu }}_{\tau }\), \({\overline{B}}^{0}\to {D}^{* +}{\ell }^{-}{\overline{\nu }}_{\ell }\), \({{{\mathcal{B}}}}({\overline{B}}^{0}\to {D}^{* +}{\tau }^{-}{\overline{\nu }}_{\tau })/{{{\mathcal{B}}}}({\overline{B}}^{0}\to {D}^{* +}{\mu }^{-}{\overline{\nu }}_{\mu })\), \({B}^{0}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }\), \(\overline{B}\to \ \ {D}^{(*)}{\ell }^{-}{\overline{\nu }}_{\ell }\), \(\overline{B}\to {D}^{* }{\tau }^{-}{\overline{\nu }}_{\tau }\), \({{{\mathcal{B}}}}[\psi (3686)\to \ \ {\pi }^{+}{\pi }^{-}J/\psi ]\), \({{{\mathcal{B}}}}[J/\psi \to \ \ {\ell }^{+}{\ell }^{-}]\), \({B}_{s}^{0}\to {\tau }^{+}{\tau }^{-}\), https://doi.org/10.1038/s41567-021-01478-8.