Article

# Addendum: Ultrahigh-energy cosmic-ray bounds on nonbirefringent modified-Maxwell theory

(Impact Factor: 4.86). 07/2008; 77(11). DOI: 10.1103/PHYSREVD.77.117901
Source: arXiv

ABSTRACT Nonbirefringent modified-Maxwell theory, coupled to standard Dirac particles, involves nine dimensionless parameters, which can be bounded by the inferred absence of vacuum Cherenkov radiation for ultrahigh-energy cosmic rays (UHECRs). With selected UHECR events, two-sided bounds on the eight nonisotropic parameters are obtained at the 10^{-18} level, together with an improved one-sided bound on the single isotropic parameter at the 10^{-19} level.

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Available from: Frans R. Klinkhamer, Sep 10, 2013
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• "We have found that the main results of previous studies [12], which assumed structureless particles for these two processes, are robust and that the two-sided bound (2.9) remains unchanged when the internal structure of the particles is incorporated. The multi-messenger astrophysics program studying high-energy phenomena with ultrahigh-energy cosmic rays [33] [34] [35], cosmic gamma rays [36], and cosmic neutrinos [37] has developed the field of astroparticle physics and now serves as a powerful tool to test fundamental physics symmetries. "
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ABSTRACT: We have performed calculations in the parton-model approximation of two nonstandard decay processes in isotropic modified Maxwell theory coupled to standard Dirac theory, with a single Lorentz-violating parameter $\kappa$ in the photonic sector. Previous calculations of these processes (vacuum Cherenkov radiation and photon decay) were performed for point-like particles and a two-sided bound on $\kappa$ at the $10^{-15}$ level was obtained from data on ultra-high-energy cosmic rays and cosmic gamma rays. The parton-model results change the decay rates by about an order of magnitude but give essentially the same bound on $\kappa$ because of the large experimental errors in the energy determination of the cosmic primaries.
Physical Review D 04/2015; 92(2). DOI:10.1103/PhysRevD.92.025007 · 4.86 Impact Factor
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• "3 As emphasized in Ref. [25] and reiterated in Refs. [8] [9], these bounds require as only input the mere existence, at the top of the Earth's atmosphere, of charged cosmic-ray primaries with travel lengths of a meter or more. Hence, these bounds are independent of the distance to the (astronomical) source. "
##### Article: Potential sensitivities to Lorentz violation from nonbirefringent modified Maxwell theory of Auger, HESS, and CTA
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ABSTRACT: Present and future ultra-high-energy-cosmic-ray facilities (e.g., the South and North components of the Pierre Auger Observatory) and TeV-gamma-ray telescope arrays (e.g., HESS and CTA) have the potential to set stringent bounds on the nine Lorentz-violating parameters of nonbirefringent modified Maxwell theory minimally coupled to standard Dirac theory. A concrete example is given how to obtain, in the coming decennia, two-sided bounds on the eight anisotropic parameters at the 10^{-20} level and an upper (lower) bound on the single isotropic parameter at the +10^{-20} (-10^{-16}) level. Comparison is made with existing and potential direct bounds from laboratory experiments. Comment: 14 pages, v4: further clarifications added
Physical review D: Particles and fields 08/2010; 82(10). DOI:10.1103/PHYSREVD.82.105024 · 4.86 Impact Factor
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• "Modified Maxwell theory is an Abelian U(1) gauge theory with a Lagrange density that consists of the standard Maxwell term and an additional Lorentz-violating bilinear term [4] [5] [6] [7]. The vierbein formalism is particularly well-suited for describing Lorentzviolating theories in curved spacetime, since it allows to distinguish between local Lorentz and general coordinate transformations [8] and to set the torsion identically to zero. 2 part of the action : "
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ABSTRACT: A Lorentz-noninvariant modification of quantum electrodynamics (QED) is considered, which has photons described by the nonbirefringent sector of modified Maxwell theory and electrons described by the standard Dirac theory. These photons and electrons are taken to propagate and interact in a Schwarzschild spacetime background. For appropriate Lorentz-violating parameters, the photons have an effective horizon lying outside the Schwarzschild horizon. A particular type of Compton scattering event, taking place between these two horizons (in the photonic ergoregion) and ultimately decreasing the mass of the black hole, is found to have a nonzero probability. These events perhaps allow for a violation of the generalized second law of thermodynamics in the Lorentz-noninvariant theory considered.
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