12, 104 (2020). High. 109, 101802 (2012). 3. The extent of the dark, medium and light blue regions shows the values allowed for RK at 1, 3 and 5 levels. J. An unbinned extended maximum-likelihood fit is made to the m(K+e+e) and m(K++) distributions of non-resonant candidates. LHCb explores the beauty of lepton universality - phys.org 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. In the muon case, K[] combinations with mass smaller than \(m_{D^0}\) are rejected. 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. The LHCb Collaboration, Test of lepton universality in beauty-quark decays, Nature Physics 18, (2022) 277-282. 12, 040 (2007). Kowalska, K., Kumar, D. & Sessolo, E. M. Implications for new physics in bs transitions after recent measurements by Belle and LHCb. Phys. Measurement of the ratio of branching fractions and difference in CP asymmetriesof the decays B+J/+ and B+J/K+. 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 process discussed above, the K++ final state is produced via a \({B}^{+}\to {X}_{q\overline{q}}{K}^{+}\) decay, where \({X}_{q\overline{q}}\) is a bound state (meson) such as the J/. Hurth, T., Mahmoudi, F. & Neshatpour, S. Implications of the new LHCb angular analysis of BK*+: hadronic effects or new physics? Instrum. & Rusov, A. V. BsK and B(s)(K)+ decays at large recoil and CKM matrix elements. Evidence for an excess of \(\overline{B}\to \ \ {D}^{(*)}{\tau }^{-}{\overline{\nu }}_{\tau }\) decays. C 74, 2897 (2014); erratum 74, 3179 (2014). Novel Tests of Lepton Universality Boost Evidence for 'New Physics Linear (top) and logarithmic (bottom) scales are shown. Phys.) Khodjamirian, A., Mannel, T. & Wang, Y.-M. BK+ decay at large hadronic recoil. The profile likelihood for the fit to the non-resonant decays is shown in Extended Data Fig. 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. Measurement of the lepton polarization and R(D*) in the decay \(\overline{B}\to {D}^{* }{\tau }^{-}{\overline{\nu }}_{\tau }\) with one-prong hadronic decays at Belle. volume18,pages 277282 (2022)Cite this article. Theor. The value of RK is a fit parameter, which is related to the signal yields and efficiencies according to. The green and purple components correspond to candidates with \({q}_{{{{\rm{t}}}}rue}^{2} > 6.0\) GeV 2/c4 and \({q}_{{{{\rm{t}}}}rue}^{2} < 1.1\) GeV 2/c4, respectively. 2006, 026 (2006). D 93, 014028 (2016). D 96 (2017) 095010 [ arXiv:1704.06659] [ INSPIRE ]. Phys. A. Bertolin. 06, 092 (2016). J. The calibrated simulation is used subsequently to obtain the m(K++) mass shape and relative fractions of these background components. LHCb collaboration et al. The B + hadron contains a beauty antiquark, b, and the K + a strange antiquark, s, such that at the quark level the decay involves a b s transition . Differential branching fraction and angular analysis of \({\Lambda }_{b}^{0}\to \Lambda {\mu }^{+}{\mu }^{-}\) decays. New result from the LHCb experiment challenges leading theory in physics The k-folding technique is used in the training and testing81. Phys. Phys. Lepton avour universality tests in electroweak penguin decays at LHCbSebastian Schmitt 1. Global analysis of bs anomalies. This effect is accounted for using simulation (Extended Data Figs. Systematic uncertainties affecting the determination of the signal yield are assessed using pseudo-experiments generated with variations of the fit model. Conversely, lepton universality is an accidental symmetry of the SM, which is not a consequence of any axiom of the theory. & Maiani, L. Weak interactions with leptonhadron symmetry. 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. The particles are required to originate from a common vertex, displaced from the protonproton interaction point, with good vertex-fit quality. 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. Reassessing the discovery potential of the B + K + + l + +l - decays in the large-recoil region: SM challenges and BSM opportunities, Physical Review D93: 014028. arXiv:1412.3183. The rJ/ single ratio is used to perform a number of additional cross-checks. For the muon modes, the residual background is combinatorial and, for the resonant mode, there is an additional contribution from B+J/+ decays with a pion misidentified as a kaon. Angular analysis of the B+K*++ decay. Beauty quarks test lepton universality - CERN Courier On the standard model predictions for RK and \({R}_{{K}^{* }}\). The B+ production kinematics are corrected using B+J/(+)K+ events. Breiman, L., Friedman, J. H., Olshen, R. A., & Stone C. J. Capdevila, B., Descotes-Genon, S., Matias, J. Int. No significant trend is observed in either rJ/ distribution. The particles are required to originate from a common vertex, with good vertex-fit quality, that is displaced significantly from all of the PVs in the event. Phys. For each electron track, a search is therefore made in the ECAL for energy deposits around the extrapolated track direction before the magnet that are not associated with any other charged tracks. (Bottom) the single ratio rJ/ relative to its average value \(< {r}_{J/\psi } >\) as a function of these variables. Uncertainties on the data points are statistical only and represent one standard deviation. Phys. J. C76, 440 (2016). Commun. 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. Test of lepton universality using B+K++ decays. 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. The invariant mass of the final state particles, m(K++), is used to discriminate between signal and background contributions, with the signal expected to accumulate around the known mass of the B+ meson. 2017, 112 (2017). The double ratio of branching fractions, R(2S), defined by. EPJ Web Conf. 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. 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. Test of lepton universality in beauty-quark decays . 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 ratio between the branching fractions of these decays is therefore predicted with \({{{\mathcal{O}}}}(1 \%)\) precision3,4,5,6,7,8. The fitted yields for the resonant and non-resonant decays are given in Extended Data Table 2. 331, 032023 (2011). The correlation is evaluated using a bootstrapping method to recompute the yields and efficiencies many times with different subsets of the data. Rev. 4. Phys. PDF Test of lepton universality in beauty-quark decays - arXiv As detailed below, percent-level control of the efficiencies is verified with a direct comparison of the B+J/(e+e)K+ and B+J/(+)K+ branching fractions in the ratio. After the application of the selection requirements, the resonant and non-resonant decays are clearly visible in the mass distributions (Fig. decays of heavy quarks. Nucl. Explore our virtual experience LHCb collaboration LHCb detector performance. In the remainder of this paper, the notation B+K++ is used to denote only decays with 1.1Test of lepton universality in beauty-quark decays - ResearchGate Measurable quantities can be predicted precisely in the decays of a charged beauty hadron, B+, into a charged kaon, K+, and two charged leptons, +. High Energy Phys. 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. Nature 546, 227 . 1, left). Lebedev Physical Institute, Russian Academy of Sciences (LPI RAS), Moscow, Russia, Universit della Basilicata, Potenza, Italy, Max-Planck-Institut fr Kernphysik (MPIK), Heidelberg, Germany, Physics and Micro Electronic College, Hunan University, Changsha City, China. Extensions to the SM that aim to address many of its shortfalls predict new virtual particles that could contribute to \(\overline{b}\to \overline{s}\) transitions (Fig. Phys. W. Altmannshofer, P.S. D 88, 032007 (2013). 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. Mar 22, 2019. Savoie Mont Blanc, CNRS, IN2P3-LAPP, Annecy, France, M. Chefdeville,D. Decamp,A. G. Downes,Ph. This resolution scaling changes the migration of candidates into the q2 region of interest by less than 1%. High. For RK the LHCb measurements are in the range 1.1

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