The corresponding parameters are then fixed in the fits to the relevant non-resonant modes. 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 suppression of \(\overline{b}\to \overline{s}\) transitions is understood in terms of the fundamental symmetries on which the SM is built. This can be interpreted as a world-leading test of lepton flavour universality in (2S)+ decays. This is known as lepton universality. 2016, 104 (2016). ISSN 1745-2473 (print). In the fits to non-resonant B+K+e+e candidates, the mass shape of the background from B+J/(e+e)K+ decays with an emitted photon that is not reconstructed is also taken from simulation and, adjusting for the relevant selection efficiency, its yield is constrained to the value from the fit to the resonant mode within its uncertainty. Rev. Huber, P. J. in Robust Estimation of a Location Parameter (eds Kotz S. & Johnson N. L.) 492518 (Springer, 1992). Test of lepton universality in beauty-quark decays This resolution scaling changes the migration of candidates into the q2 region of interest by less than 1%. 108, 081807 (2012). The calibrated simulation is used subsequently to obtain the m(K++) mass shape and relative fractions of these background components. Distribution of the invariant mass m(K+e+e) for B+K+e+e candidates. De Aguiar Francisco,S. De Capua,D. Dutta,C. Fitzpatrick,E. Gersabeck,M. Gersabeck,L. Grillo,M. Hilton,G. Lafferty,J. J. Phys. For the muon modes, the superior mass resolution allows a fit in a reduced m(K++) mass range compared with the electron modes. 82,83,84,85,86,87,88. 2017, 36 (2017). 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. Hambrock, C., Hiller, G., Schacht, S. & Zwicky, R. BK* form factors from flavor data to QCD and back. Measurement of the ratio of branching fractions \({{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\tau }^{+}{\nu }_{\tau })/{{{\mathcal{B}}}}{{{\mathcal{B}}}}({B}_{c}^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu })\). Prog. Lepton avour universality tests in electroweak penguin decays at LHCbSebastian Schmitt 1. 3. which does not benefit from the same cancellation of systematic effects. The results indicate that particles are not behaving in the way they should. The dominant such background for the non-resonant and resonant modes comes from partially reconstructed B(0,+)K+(,0)e+e and B(0,+)J/(e+e)K+(,0) decays, respectively, where the pion is not included in the B+ candidate. 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. So far, LHCb has collected 260 billion bottom-quark antiquark pairs in experimental runs using protons with 7 and 8 tera-electron-volt (TeV) center-of-mass energies. Energy Phys. Rev. Novel Tests of Lepton Universality Boost Evidence for 'New Physics The consistency of this ratio with unity demonstrates control of the efficiencies well in excess of that needed for the determination of RK. Bremsstrahlung photons can be added to none, either or both of the final-state e+ and e candidates. D 97, 072013 (2018). J. J. Long-distance effects in BK* from analyticity. Eur. (Left, with log y-scale) the bremsstrahlung correction to the momentum of the electron is applied, resulting in a tail to the right. Measurable quantities can be predicted precisely in the decays of a charged beauty hadron, B +, into a charged kaon, K +, and two charged leptons, + . Straub, D. M. flavio: a python package for flavour and precision phenomenology in the standard model and beyond. The signal is represented by the orange shaded region and the various cascade background contributions by red, dark blue and light blue shaded regions. J. We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (the Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland) and NERSC (United States). Phys. Other experiments should also be able to determine RH ratios, with the Belle II experiment in particular expected to have competitive sensitivity72. 2019, 123C01 (2019); erratum 2020, 029201 (2020). The measurement made by the LHCb team compares two types of decays of beauty quarks. Steven D. Bass, Albert De Roeck & Marumi Kado, Nature Physics Lett. The efficiency of the non-resonant B+K+e+e decay therefore needs to be known only relative to that of the resonant B+J/(e+e)K+ decay, rather than relative to the B+K++ decay. Test of lepton universality in beauty-quark decays - Academia.edu Observables studied include rare meson decays, flavor oscillations of neutral mesons, rare lepton decays, and dipole moments. Following the procedure described in refs. High. Test of lepton universality with beauty baryons, RpK A. Aaij, R. et al. & Atwood, D. Rate difference between bs+ and bse+e in supersymmetry with large tan . Phys. D 103, 015030 (2021). (Right, with linear y-scale) the mass is computed only from the track information. 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. The 1.9% uncertainty on the B+J/K+ branching fraction2 gives rise to the dominant systematic uncertainty. The LHCb collaboration et al. The PVs are reconstructed by searching for space points where an accumulation of track trajectories is observed. High. High Energy Phys. 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. For the non-resonant muon mode and for each of the three different trigger categories of the non-resonant electron mode, a single BDT classifier is trained for the 7 and 8TeV data, and an additional classifier is trained for the 13TeV data. Methods A 764, 150155 (2014). J. In December 22 the LHCb collaboration announced that the results of a new analysis of bs decays show an agreement with the SM. The width of the constraint is determined by adding the contributions from the different sources in quadrature. Phys. In the muon case, K[] combinations with mass smaller than \(m_{D^0}\) are rejected. Theor. Rev. Measurement of the ratio of branching fractions \({{{\mathcal{B}}}}({\overline{B}}^{0}\to {D}^{* +}{\tau }^{-}{\overline{\nu }}_{\tau })/{{{\mathcal{B}}}}({\overline{B}}^{0}\to {D}^{* +}{\mu }^{-}{\overline{\nu }}_{\mu })\). Back,T. Blake,A. Brossa Gonzalo,M. F. Cicala,C. M. Costa Sobral,L. M. Garcia Martin,T. Gershon,R. J. Phys. Jger, S. and Martin, J. 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. Yields of the nonresonant and resonant decay modes obtained from the fits to the data. Ser. Methods A 462, 152155 (2001). Martnez Santos, D. & Dupertuis, F. Mass distributions marginalized over per-event errors. D 92, 072014 (2015). $$B_{\mathrm{s}}^0$$ The proportion of signal candidates that migrate in and out of the q2 region of interest is on the order of 10%. volume18,pages 277282 (2022)Cite this article. 8 Candidate invariant mass distributions. Phys. Rev. Exp. Measurements of other RH observables with the full LHCb dataset will provide further information on the quark-level processes measured. High. Geant4: a simulation toolkit. According to the Standard Model of particle physics, particles such as beauty quarks should decay into either muons or electrons in equal measure. Wang, Y. Sign up for the Nature Briefing newsletter what matters in science, free to your inbox daily. The red line indicates the prediction from the SM. These two processes are separated by applying a requirement on q2. 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. Compared with the previous LHCb RK result11, the experimental method is essentially identical but the analysis uses an additional 4fb1 of data collected in 2017 and 2018. Test of Lepton Flavour Universality using a measurement of R(D*) with Aaltonen, T. et al. LHCb data used in this analysis will be released according to the LHCb external data access policy, which can be downloaded from http://opendata.cern.ch/record/410/files/LHCb-Data-Policy.pdf. These include the decays B+K++, and misreconstructed B+J/(+)K+ and B+(2S)(+)K+ decays. Search for lepton-universality violation in B+K++ decays. Wei J.-T. et al. Lett. Isidori, G., Nabeebaccus, S. & Zwicky, R. QED corrections in \(\overline{B}\to \overline{K}{{{{\rm{\ell }}}}}^{+}{{{{\rm{\ell }}}}}^{-}\) at the double-differential level. 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. 3). What our students say. Bezshyiko,A. Buonaura,D. De Simone,V. Denysenko,J. Eschle,M. Ferrillo,D. Lancierini,O. Lantwin,A. Mathad,K. Mller,P. Owen,N. Serra,R. Silva Coutinho,O. Steinkamp&Z. Wang, Oliver Lodge Laboratory, University of Liverpool, Liverpool, UK, T. Ackernley,T. J. V. Bowcock,G. Casse,A. J. Chadwick,C. A. Chavez Barajas,K. Dreimanis,S. Farry,V. Franco Lima,T. Halewood-leagas,J. P. Hammerich,T. Harrison,K. Hennessy,D. Hutchcroft,P. J. Marshall,J. V. Mead,K. Rinnert,E. Rodrigues,T. Shears,K. A. Thomson,E. Vilella Figueras,H. M. Wark&L. E. Yeomans, Instituto Galego de Fsica de Altas Enerxas (IGFAE), Universidade de Santiago de Compostela, Santiago de Compostela, Spain, B. Adeva,P. Baladron Rodriguez,O. Boente Garcia,A. Brea Rodriguez,A. Casais Vidal,V. Chobanova,X. Cid Vidal,J. Dalseno,L. Dieste Maronas,A. Fernandez Prieto,A. Gallas Torreira,B. Garcia Plana,A. Giovent,J. Lomba Castro,D. Martinez Santos,C. J. Parkinson,M. Plo Casasus,C. Prouve,M. Romero Lamas,A. Romero Vidal,J. J. Saborido Silva,C. Santamarina Rios,S. Sellam,R. Vazquez Gomez&P. Vazquez Regueiro, H.H. D 2, 12851292 (1970). Particle Data Group et al. The B+J/(+)K+ decays are not suppressed and hence have a branching fraction orders of magnitude larger than that of B+K++ decays. Only potentially interesting events, selected using real-time event filters referred to as triggers, are recorded. 4. & Tech. There are excellent prospects for all of the above and further measurements with the much larger samples that will be collected with the upgraded LHCb detector from 2022 and, in the longer term, with the LHCb Upgrade II71. 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. For the non-resonant B+K+e+e decays, the systematic uncertainties are dominated by the modelling of the signal and background components used in the fit. & Maiani, L. Weak interactions with leptonhadron symmetry. Uncertainties on the data points are statistical only and represent one standard deviation. 2006, 026 (2006). J. J. Electroweak Penguin Decays at LHCb - ResearchGate 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). 103, 171801 (2009). The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction. 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. Phys. Phys. Lett. Using pseudo-experiments based on the null hypothesis, the data suggest that the RK value from the new portion of the data is compatible with that from the previous sample with a P value of 95%. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. Phys. 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 results are consistent between the different data-taking periods and with previous LHCbmeasurements37. 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. The latter also tend to accumulate around specific values of m(K++). 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.
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