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. Khodjamirian, A., Mannel, T., Pivovarov, A. Recent evidence of a possible fifth force of nature The LHCb simulation application, Gauss: design, evolution and experience. J. Differential branching fraction and angular analysis of the decay B0K+I+in the \({K}_{0,2}^{* }{(1430)}^{0}\) region. Rev. The B+J/(+)K+ decays are not suppressed and hence have a branching fraction orders of magnitude larger than that of B+K++ decays. The results are consistent between the different data-taking periods and with previous LHCbmeasurements37. Analogous background sources with a misidentified particle are reduced by applying a similar veto, but with the lepton mass hypothesis changed to that of a pion (denoted []). LHCb collaboration. The double ratio of branching fractions, R(2S), defined by. (Left, with log y-scale) the bremsstrahlung correction to the momentum of the electron is applied, resulting in a tail to the right. The Standard Model of particle physics currently provides our best description of fundamental particles and their interactions. Phys. C 79, 719 (2019). To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Glashow, S. L., Iliopoulos, J. An electron that emits a bremsstrahlung photon due to interactions with the material of the detector downstream of the dipole magnet results in the photon and electron depositing their energy in the same ECAL cells and therefore in a correct measurement of the original energy of the electron in the ECAL. (Bottom) the single ratio rJ/ relative to its average value \(< {r}_{J/\psi } >\) as a function of these variables. Improved lepton universality measurements show agreement with the Test of lepton universality with B0K*0+ decays. Lessons from the B0,+K*0,++ angular analyses. 3, S08005 (2008). Ciuchini, M. et al. Instrum. 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. Hambrock, C., Hiller, G., Schacht, S. & Zwicky, R. BK* form factors from flavor data to QCD and back. Phys. Test of lepton universality in beauty-quark decays - Nature Lett. 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%. Part. This estimate takes into account the spectrum of the relevant variables in the non-resonant decay modes of interest and is compatible with the estimated systematic uncertainties on RK. The LHCb collaboration et al. Aaij, R. et al. A. Bertolin. The analogous ratio has also been measured for \({\Lambda }_{b}^{0}\) decays with H=pK and is compatible with unity at the level of one standard deviation23. Test of lepton universality using B 0 K S0 l + l - and B + K* + l + l - decays. Lett. Test of lepton flavor universality and search for lepton flavor violation in BK decays. Electroweak Penguin Decays at LHCb - ResearchGate The corresponding significance in terms of standard deviations is computed using the inverse Gaussian cumulative distribution function for a one-sided conversion. 53, 270278 (2006). A. The trigger selection algorithms are based on identifying key characteristics of B hadrons and their decay products, such as high pT final-state particles, and a decay vertex that is significantly displaced from any of the PVs in the event. Extended Data Fig. References to the extensive literature describing these new physics models can be found in the Supplementary Information. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. explanations of this apparent violation of lepton universality for decays . 113, 151601 (2014). Extended Data Table 1 Nonresonant and resonant mode. 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. 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. New result from the LHCb experiment challenges leading theory in physics Ratio between the likelihood value (L) and that found by the fit (\({L}_{\max }\)) as a function of RK. The distributions are all normalised to unity. Global analysis of bs anomalies. 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 majority of the sources of systematic uncertainty affect the relative efficiencies between non-resonant and resonant decays. C 82, 7 (2022). Distribution of m(K+e+e) in simulated B+K+e+e decays. 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. Phys. 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. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. High. We thank our colleagues in the CERN accelerator departments for the excellent performance of the LHC, and the technical and administrative staff at the LHCb institutes. Allison, J. et al. 24, 01025 (2020). Rev. volume18,pages 277282 (2022)Cite this article. The mass distributions are shown in Extended Data Fig. Breiman, L., Friedman, J. H., Olshen, R. A., & Stone C. J. Rev. 3 Resonant candidates invariant mass distributions. The standard model of particle physics currently provides our best description of fundamental particles and their interactions. Phys. 1, left). Alok, A. K., Dighe, A., Gangal, S. & Kumar, D. Continuing search for new physics in bs decays: two operators at a time. where N(X) indicates the yield of decay mode X and (X) is the efficiency for selecting decay mode X. Precision measurements of \({{{\mathcal{B}}}}[\psi (3686)\to \ \ {\pi }^{+}{\pi }^{-}J/\psi ]\) and \({{{\mathcal{B}}}}[J/\psi \to \ \ {\ell }^{+}{\ell }^{-}]\). Lett. where the first uncertainty is statistical and the second systematic. The Belle collaboration et al. 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. Lepton Flavour Universality can be studied in two classes of B meson decays in which a beauty b quark can be transformed into either a strange quark (bs) or into a charm quark (bc). 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.