4 research outputs found
Constraints on Lorentz Invariance Violating Quantum Gravity and Large Extra Dimensions Models using High Energy Gamma Ray Observations
Observations of the multi-TeV spectra of the nearby BL objects Mkn 421 and
Mkn 501 exhibit the high energy cutoffs predicted to be the result of
intergalactic annihilation interactions, primarily with infrared photons having
a flux level as determined by various astronomical observations. After
correction for this absorption effect, the derived intrinsic spectra of these
multi-TeV sources can be explained within the framework of simple synchrotron
self-Compton emission models. Stecker and Glashow have shown that the existence
of such annihilations via electron-positron pair production interactions up to
an energy of 20 TeV puts strong constraints on Lorentz invariance violation.
Such constraints have important implications for Lorentz invariance violating
(LIV) quantum gravity models as well as LIV models involving large extra
dimensions. We also discuss the implications of observations of high energy
gamma-rays from the Crab Nebula on constraining quantum gravity models.Comment: Accepted for publication in Astroparticle Physics, nine pages, ref.
to loop quantum gravity remove
Cosmic Physics: The High Energy Frontier
Cosmic rays have been observed up to energies times larger than those
of the best particle accelerators. Studies of astrophysical particles (hadrons,
neutrinos and photons) at their highest observed energies have implications for
fundamental physics as well as astrophysics. Thus, the cosmic high energy
frontier is the nexus to new particle physics. This overview discusses recent
advances being made in the physics and astrophysics of cosmic rays and cosmic
gamma-rays at the highest observed energies as well as the related physics and
astrophysics of very high energy cosmic neutrinos. These topics touch on
questions of grand unification, violation of Lorentz invariance, as well as
Planck scale physics and quantum gravity.Comment: Topical Review Paper to be published in the Journal of Physics G, 50
page