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Probing quantum gravity using photons from a flare of the active galactic nucleus Markarian 501 observed by the MAGIC telescope
(2008)Physics Letters BWe analyze the timing of photons observed by the MAGIC telescope during a flare of the active galactic nucleus Mkn 501 for a possible correlation with energy, as suggested by some models of quantum gravity (QG), which predict a vacuum refractive index ≃ 1 + (E / MQGn)n, n = 1, 2. Parametrizing the delay between γ-rays of different energies as Δ t = ± τl E or Δ t = ± τq E2, we find τl = (0.030 ± 0.012) s / GeV at the 2.5-σ level, and τq = ...Journal Article -
Study of hadronic event shape in flavour tagged events in e+e- annihilation at ⟨√s⟩ = 197 GeV
(2008)PMC Physics. AResults are presented from a study of the structure of hadronic events in high-energy e+e- interactions detected by the L3 detector at LEP. Various event shape distributions and their moments are measured at several energy points at and above the Z-boson mass. The event flavour is tagged by using the decay characteristics of b-hadrons. Measurements of distributions of event shape variables for all hadronic events, for light (u, d, s, c) ...Journal Article