test of lepton universality in beauty quark decays nature

04, 016 (2017). Instrum. In the latter two decays, the kaon is misidentified as a lepton and the lepton (of the same electric charge) as a kaon. Distribution of m(K+e+e) in simulated B+K+e+e decays. D 2, 12851292 (1970). 12, 131 (2014). 2014, 133 (2014). 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. Stanford Libraries' official online search tool for books, media, journals, databases, government documents and more. Uncertainties on the data points are the combination of statistical and systematic and represent one standard deviation. The resonant yields are determined from separate fits to the mass, mJ/(K++), formed by kinematically constraining the dilepton system to the known J/ mass2 and thereby improving the mass resolution. Eur. 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. Measurement of ${{{\mathcal{R}}}}(D)$ and ${{{\mathcal{R}}}}({D}^{* })$ with a semileptonic tagging method. High Energy Phys. the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in For the electron modes that dictate the RK precision, this requirement reduces the combinatorial background by approximately 99% while retaining 85% of the signal mode. The corresponding significance in terms of standard deviations is computed using the inverse Gaussian cumulative distribution function for a one-sided conversion. Phys. This resolution scaling changes the migration of candidates into the q2 region of interest by less than 1%. The y-axis in each figure shows the number of candidates in an interval of the indicated width. Particle Data Group et al. The quoted uncertainty is the combination of statistical and systematic effects. Nucl. Such decays are highly suppressed1, and the fraction of B+ hadrons that decay into this final state (the branching fraction, ${{{\mathcal{B}}}}$) is on the order of 106 (ref. $$\overline B_{\mathrm{s}}^0$$ 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. Conf. Sjstrand, T., Mrenna, S. & Skands, P. A brief introduction to PYTHIA 8.1. Phys. 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. where the first uncertainty is statistical and the second systematic. Bordone, M., Isidori, G. & Pattori, A. This charmonium resonance subsequently decays into two leptons, J/+. 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. Article . Measurement of the ratio of branching fractions and difference in CP asymmetriesof the decays B+J/+ and B+J/K+. The EvtGen particle decay simulation package. Energy Phys. High. 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. Extended Data Fig. Measurement of the ratio of branching fractions ${{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\tau }^{+}{\nu }_{\tau })/{{{\mathcal{B}}}}{{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu })$. 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. For the electron mode, this requirement is illustrated in Extended Data Fig. D 92, 072014 (2015). Test of lepton universality in beauty-quark decays, ${q}_{\min }^{2} < {q}^{2} < {q}_{\max }^{2}$, $${R}_{H}\equiv \frac{\int\nolimits_{{q}_{\min }^{2}}^{{q}_{\max }^{2}}\frac{{{{\rm{d}}}}{{{\mathcal{B}}}}\ \ (B\to H{\mu }^{+}{\mu }^{-})}{{{{\rm{d}}}}{q}^{2}}{{{\rm{d}}}}{q}^{2}}{\int\nolimits_{{q}_{\min }^{2}}^{{q}_{\max }^{2}}\frac{{{{\rm{d}}}}{{{\mathcal{B}}}}\ \ (B\to H{e}^{+}{e}^{-})}{{{{\rm{d}}}}{q}^{2}}{{{\rm{d}}}}{q}^{2}}\,.$$, $\overline{b}\to \overline{s}{\mu }^{+}{\mu }^{-}$, $\overline{b}\to \overline{c}{\ell }^{+}{\nu }_{\ell }$, ${B}^{+}\to {X}_{q\overline{q}}{K}^{+}$, $${R}_{K}=\frac{{{{\mathcal{B}}}}\ \ ({B}^{+}\to {K}^{+}{\mu }^{+}{\mu }^{-})}{{{{\mathcal{B}}}}\ \ ({B}^{+}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){K}^{+})}/\frac{{{{\mathcal{B}}}}\ \ ({B}^{+}\to {K}^{+}{e}^{+}{e}^{-})}{{{{\mathcal{B}}}}\ \ ({B}^{+}\to J/\psi (\to {e}^{+}{e}^{-}){K}^{+})}\ .$$, $${r}_{J/\psi }={{{\mathcal{B}}}}\ ({B}^{+}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){K}^{+})/{{{\mathcal{B}}}}\ ({B}^{+}\to J/\psi (\to {e}^{+}{e}^{-}){K}^{+}),$$, ${B}^{+}\to {\overline{D}}^{0}(\to {K}^{+}{e}^{-}{\overline{\nu }}_{e}){e}^{+}{\nu }_{e}$, $$\begin{array}{l}{R}_{\psi (2S)}\\=\frac{{{{\mathcal{B}}}}\ ({B}^{+}\to \psi (2S)(\to {\mu }^{+}{\mu }^{-}){K}^{+})}{{{{\mathcal{B}}}}\ ({B}^{+}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){K}^{+})}/\frac{{{{\mathcal{B}}}}\ ({B}^{+}\to \psi (2S)(\to {e}^{+}{e}^{-}){K}^{+})}{{{{\mathcal{B}}}}\ ({B}^{+}\to J/\psi (\to {e}^{+}{e}^{-}){K}^{+})}\ ,\end{array}$$, $${R}_{K}(1.1 < {q}^{2} < 6.0\,{{{{\rm{GeV}}}}}^{2}\,{c}^{-4})=0.84{6}_{-0.039-0.012}^{+0.042+0.013}\ ,$$, ${R}_{K}=0.84{6}_{-\ 0.041}^{+\ 0.044}$, ${B}^{0}\to {K}_{{{{\rm{S}}}}}^{0}{\ell }^{+}{\ell }^{-}$, ${{{\rm{d}}}}{{{\mathcal{B}}}}\ ({B}^{+}\to {K}^{+}{\mu }^{+}{\mu }^{-})/{{{\rm{d}}}}{q}^{2}$, $$\begin{array}{rcl}\frac{{{{\rm{d}}}}{{{\mathcal{B}}}}\ ({B}^{+}\to {K}^{+}{e}^{+}{e}^{-})}{{{{\rm{d}}}}{q}^{2}}(1.1 < {q}^{2} < 6.0\,{{{{\rm{GeV}}}}}^{2}{c}^{-4})\\=(28. Bainbridge, R. on behalf of the CMS collaboration Recording and reconstructing 10 billion unbiased b hadron decays in CMS. The simulated data used in this analysis are produced using the software described in refs. To avoid unconscious bias, the analysis procedure was developed and the cross-checks described below performed before the result for RK was examined. 9,10), is defined in the dilepton mass-squared range ${q}_{\min }^{2} < {q}^{2} < {q}_{\max }^{2}$ as. Mar 22, 2019. Background from other exclusive B-hadron decays requires at least two particles to be misidentified. 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. which does not benefit from the same cancellation of systematic effects. 11, and only the main analysis steps are reviewed here. D 68, 094016 (2003). D 97, 012004 (2018). C 80, 252 (2020). 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. Geng, L.-S. et al. 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. The 3,85070 B+K++ decay candidates that are observed are used to compute the B+K++ branching fraction as a function of q2. 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. Phys. The LHCb collaboration et al. Rev. 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. Rev. Phys. 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. J. The calibrated simulation is used subsequently to obtain the m(K++) mass shape and relative fractions of these background components. Although this may not be happening, it suggests a new study by the LHCb Collaboration at CERN. High. This is known as lepton universality. Test of lepton flavor universality and search for lepton flavor violation in BK decays. Bobeth, C., Chrzaszcz, M., van Dyk, D. & Virto, J. Phys. Aaij, R. et al. Rev. Bhupal Dev and A. Soni, {R}_ {D^ {\left (\ast \right)}} anomaly: A possible hint for natural supersymmetry with R-parity violation, Phys. The major challenge of the measurement is then correcting for the efficiency of the selection requirements used to isolate signal candidates and reduce background. Lett. Phys. D 88, 072012 (2013). 2014, 125 (2014). 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. Measurements of branching fractions, rate asymmetries, and angular distributions in the rare decays BK+ and BK*+. The J/ meson consists of a charm quark and antiquark, $c\overline{c}$, and is produced resonantly at q2=9.59GeV2c4. Bremsstrahlung photons can be added to none, either or both of the final-state e+ and e candidates. Energy Phys. Martin, B. R., and Shaw, G. (2017). Rev. The red line indicates the prediction from the SM. J. Evidence for an excess of $\overline{B}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }$ decays. C 82, 7 (2022). The resulting variations are typically at the permille level and hence well within the estimated systematic uncertainty on RK. For each of the classifiers, a requirement is placed on the output variable to maximize the predicted significance of the non-resonant signal yield. Background from decays with a photon converted into an e+e pair are also negligible due to the q2 selection. Internet Explorer). 24, 01025 (2020). The muon BDT classifier has similar performance. Zenodo https://doi.org/10.5281/zenodo.4586379 (2021). Aaij, R. et al. The LHCb collaboration et al. On the impact of power corrections in the prediction of BK*+ observables. Phys. 0 Lett. Rev. 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. The 1.9% uncertainty on the B+J/K+ branching fraction2 gives rise to the dominant systematic uncertainty. B Aubert, B. et al. 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. Rev. Steven D. Bass, Albert De Roeck & Marumi Kado, Nature Physics Distribution of the invariant mass m(J/)(K++) for candidates with electron (left) and muon (right) pairs in the final state for the non-resonant B+K++ signal channels (top) and resonant B+J/(+)K+ decays (bottom). Particle physicists have therefore been searching for new physics, that is, new particles and interactions that can explain the SMs shortcomings. 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. Rev. Whenever a process is specified in this paper, the inclusion of the charge-conjugate mode is implied. J. C77, 377 (2017). Distribution of the invariant mass m(K++) for nonresonant candidates in the (left) sample previously analysed11 and (right) the new data sample. Khodjamirian, A. 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. Phys. Preprint at https://arxiv.org/abs/1406.0566 (2014). Phys. Particle Physics (4th ed. 3 Resonant candidates invariant mass distributions. Prog. 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. Ciuchini, M. et al. The large interaction strengths preclude predictions of QCD effects with the perturbation techniques used to compute the electroweak force amplitudes, and only approximate calculations are currently possible. Measurements of the angular distributions in the decays BK(*)+ at CDF. Such background is reduced to a negligible level by particle identification criteria. To obtain These ratios have been determined to be 2.12.5 standard deviations below their respective SM expectations3,4,5,6,7,16,17,18,19,20,21,22. B 781, 517541 (2018). 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. Simulated events are used to derive the two ratios of efficiencies needed to form RK using equation (2). Rev. The ratio of branching fractions, RH (refs. LHCb is a specialized b-physicsexperiment, designed primarily to measure the parameters of CP violationin the interactions of b-hadrons(heavy particles containing a bottom quark). J. Rev. Savoie Mont Blanc, CNRS, IN2P3-LAPP, Annecy, France, M. Chefdeville,D. Decamp,A. G. Downes,Ph. 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. A test statistic is constructed that is based on the likelihood ratio between two hypotheses with common (null) or different (test) RK values for the part of the sample analysed previously (7, 8 and part of the 13TeV data) and for the new portion of the 13TeV data. J. 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. Hambrock, C., Hiller, G., Schacht, S. & Zwicky, R. BK* form factors from flavor data to QCD and back. The LHCb collaboration et al. The notation ${\pi }_{[\to {e}^{-}]}^{-}$ (${e}_{[\to {\pi }^{-}]}^{-}$) is used to denote an pion (electron) that is reconstructed as an electron (pion). Performance of the ATLAS level-1 topological trigger in run 2. Rev. New physics in bs+ confronts new data on lepton universality. 4. Rev. J. Instrum. Towards the discovery of new physics with lepton-universality ratios of bs decays. J. After the application of the selection requirements, the resonant and non-resonant decays are clearly visible in the mass distributions (Fig. The Belle collaboration et al. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. Prog. The shape of the B+J/+ background contribution is taken from simulation, but the size with respect to the B+J/K+ mode is constrained using the known ratio of the relevant branching fractions2,94 and efficiencies. 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. The decays used in this analysis to study lepton universality are extremely rare. s On the standard model predictions for RK and ${R}_{{K}^{* }}$. Eur. The consistency of this ratio with unity demonstrates control of the efficiencies well in excess of that needed for the determination of RK. A multivariate algorithm is used for the identification of displaced vertices consistent with the decay of a B hadron77,78. 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. Publishers note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. 12, 040 (2007). Phys. The mass-shape parameters are derived from the calibrated simulation. Energy Phys. Lepton-flavor-dependent angular analysis of BK*+. 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. Alok, A. K., Dighe, A., Gangal, S. & Kumar, D. Continuing search for new physics in bs decays: two operators at a time. D 96 (2017) 095010 [ arXiv:1704.06659] [ INSPIRE ]. 08, 098 (2016). High. High Energy Phys. 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. 331, 032023 (2011). The veto requirements retain 97% of B+K++ and 95% of B+K+e+e decays passing all other selection requirements. 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. Blum, A., Kalai, A. 2015, 115 (2015); erratum 2018, 145 (2018). Measurement of the ratio of branching fractions ${{{\mathcal{B}}}}({\overline{B}}^{0}\to {D}^{* +}{\tau }^{-}{\overline{\nu }}_{\tau })/{{{\mathcal{B}}}}({\overline{B}}^{0}\to {D}^{* +}{\mu }^{-}{\overline{\nu }}_{\mu })$. High Energy Phys. Phys. In the fit for RK, these yields and the efficiencies are incorporated as Gaussian-constraint terms. A. Rodriguez Lopez, Universitt Bonn Helmholtz-Institut fr Strahlen und Kernphysik, Bonn, Germany, Hanoi University of Science, Hanoi, Vietnam, P.N. This uncertainty includes both statistical and systematic effects, where the latter dominate. Energy Phys. Combining the uncertainties gives ${R}_{K}=0.84{6}_{-\ 0.041}^{+\ 0.044}$. 115, 111803 (2015); erratum 115, 159901 (2015). Lepton avour universality tests in electroweak penguin decays at LHCbSebastian Schmitt 1. The raw data in all of the figures of this paper, and additional supplementary material, can be downloaded from https://cds.cern.ch/record/2758740, where no access codes are required. Such a modification can be realized in new physics models with an additional heavy neutral boson or with leptoquarks. Measurement of an excess of $\overline{B}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }$ decays and implications for charged Higgs bosons.

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