Abstract
We point out that violation of Lorentz invariance affects the interaction of high-energy photons with the Earth's atmosphere and magnetic field. In certain parameter region this interaction becomes suppressed and the photons escape observation passing through the atmosphere without producing air showers. We argue that a detection of photon-induced air showers with energies above 10^19 eV, implying the absence of suppression as well as the absence of photon decay, will put tight double-sided limits on Lorentz violation in the sector of quantum electrodynamics. These constraints will be by several orders of magnitude stronger than the existing ones and will be robust against any assumptions about the astrophysical origin of the detected photons.
Highlights
One of the important open questions in astroparticle physics is the presence of a photon component in the ultrahigh-energy cosmic rays (UHECR)
We argue that a detection of photon-induced air showers with energies above 1019 eV, implying the absence of suppression as well as the absence of photon decay, will put tight double-sided limits on Lorentz violation in the sector of quantum electrodynamics
This is consistent with the prediction made long ago by Greisen, Zatsepin, and Kuzmin (GZK) [4,5] that the flux of primary protons would be depleted at these energies due to pion production on the cosmic microwave background (CMB)
Summary
One of the important open questions in astroparticle physics is the presence of a photon component in the ultrahigh-energy cosmic rays (UHECR). In this frame UHECR particles have a huge energy which may lead to the enhancement of LV and to observable deviations from the standard physics It has been proposed [23,24] that a detection of UHE photon flux compatible with the GZK prediction will impose strong constraints on LV in the sector of quantum electrodynamics (QED). Assuming that the primary cosmic rays are extragalactic protons and that all UHE photons come from the GZK process, these papers simulate the propagation of UHE photons through the interstellar medium and their resulting flux on Earth in a family of LV models They showed that, depending on the region in the LV parameter space, the flux will be either highly suppressed due to the vacuum decay of photons into eþe−; or, on the contrary, it will be enhanced above the existing bounds due to the weakening of the UHE photon depletion. It was discussed in the context of TeV gamma rays in [27]
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