![]() ![]() As the detector signature of each resonant decay is similar to that of its corresponding non-resonant decay, systematic uncertainties that would otherwise dominate the calculation of these efficiencies are suppressed. 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/ ψ( → e e −) K decay, rather than relative to the B → K μ μ − decay. In this equation, each branching fraction can be replaced by the corresponding event yield divided by the appropriate overall detection efficiency ( Methods), as all other factors needed to determine each branching fraction individually cancel out. 2, 65), the R K ratio is determined via the double ratio of branching fractions Since the J/ ψ → ℓ ℓ − branching fractions are known to respect lepton universality to within 0.4% (refs. Dissertation (Ph.D.), California Institute of Technology. To help overcome the challenge of modelling precisely the different electron and muon reconstruction efficiencies, the branching fractions of B → K ℓ ℓ − decays are measured relative to those of B → J/ ψ K decays 64. Jones, Lawrence Aston (1995) A measurement of the mass of the tau lepton. The total decay width of a particle,, is proportional to the fifth power of its mass, m, m 5 We also know that the dominant decays of the tau lepton are e e d u with branching ratios of approximately 20, 20 and 60, respectively. ![]() ![]() In the remainder of this paper, the notation B → K ℓ ℓ − is used to denote only decays with 1.1 < q 2 < 6.0 GeV 2 c −4, which are referred to as non-resonant, whereas B → J/ ψ( → ℓ ℓ −) K decays are denoted resonant. The B hadron contains a beauty antiquark, \(\overline\) resonances, such as the ϕ(1020) meson. Measurable quantities can be predicted precisely in the decays of a charged beauty hadron, B , into a charged kaon, K , and two charged leptons, ℓ ℓ −. One method to search for new physics is to compare measurements of the properties of hadron decays, where hadrons are bound states of quarks, with their SM predictions. Particle physicists have therefore been searching for ‘new physics’, that is, new particles and interactions that can explain the SM’s shortcomings. The SM is unable to explain cosmological observations of the dominance of matter over antimatter, the apparent dark matter content of the Universe, or the patterns seen in the interaction strengths of the particles. The LHC might also produce vector-like taus, particles with similar properties as the Standard Model tau lepton, except that it would have a. An integrated luminosity of 22.3 pbl at 4.03 GeV, corresponding. If it is composite, then the LHC could produce its excited state: the excited tau lepton. An upper limit for the mass of the tau neutrino has been determined using the decay r Knrvx. However, it is clear that the model is incomplete. One particle under investigation by the ATLAS experiment is the tau lepton, a heavier analogue of the electron. Grand Unified Theories (GUTs) were proposed to unify all fundamental interactions and elementary particles described by the Standard Model (SM) at the electroweak (EW) scale.The standard model (SM) of particle physics provides precise predictions for the properties and interactions of fundamental particles, which have been confirmed by numerous experiments since the inception of the model in the 1960s. ![]()
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