21 research outputs found
Constraints on violation of Lorentz invariance from atmospheric showers initiated by multi-TeV photons
We discuss the effect of hypothetical violation of Lorentz invariance at high
energies on the formation of atmospheric showers by very-high-energy gamma
rays. In the scenario where Lorentz invariance violation leads to a decrease of
the photon velocity with energy the formation of the showers is suppressed
compared to the Lorentz invariant case. Absence of such suppression in the
high-energy part of spectrum of the Crab nebula measured independently by HEGRA
and H.E.S.S. collaborations is used to set lower bounds on the energy scale of
Lorentz invariance violation. These bounds are competitive with the strongest
existing constraints obtained from timing of variable astrophysical sources and
the absorption of TeV photons on the extragalactic background light. They will
be further improved by the next generation of multi-TeV gamma-ray
observatories.Comment: 21 pages, 4 figures. References adde
New constraints on Lorentz Invariance violation from Crab Nebula spectrum beyond TeV
Recently two collaborations, Tibet and HAWC, presented new measurements of
gamma-ray spectrum from Crab Nebula
\cite{Amenomori:2019rjd},\cite{Abeysekara:2019edl} which continues beyond
TeV. We use these data to establish two-sided constraints on parameters of
Lorentz Invariance violation in quantum electrodynamics. The limits on Lorentz
violating mass scale for quartic dispersion relation are $4.1\times 10^{14}\
\mbox{GeV}1.9\times 10^{13}\ \mbox{GeV}1.4\times 10^{12}$ GeV (suppression of
shower formation) for subluminal case.Comment: 9 page
Resonant generation of high-order harmonics in nonlinear electrodynamics
We study the process of resonant generation of high-order harmonics in a
closed cavity in the model of vacuum nonlinear electrodynamics. Concretely, we
study the possibility of resonant generation of the third harmonic induced by a
single electromagnetic mode in a radiofrequency cavity, as well as resonant
generation of a combined frequency mode induced by two pump modes (
and ). We explicitly show that the third harmonic as well as the
combined frequency mode are not resonantly amplified,
while the signal mode is amplified for certain cavity
geometry. We discuss the process from the point of view of quantum theory.Comment: 8 pages, 1 figure, 4 tables. Contribution to proceedings of
International Conference on Quantum Field Theory, High-Energy Physics, and
Cosmology (July 18-21, 2022; JINR, Dubna, Russia), to be published in Phys.
Part. Nucl. Let
On calculation of cross sections in Lorentz violating theories
We develop a systematic approach to the calculation of scattering cross
sections in theories with violation of the Lorentz invariance taking into
account the whole information about the theory Lagrangian. As an illustration
we derive the Feynman rules and formulas for sums over polarizations in spinor
electrodynamics with Lorentz violating operators of dimensions four and six.
These rules are applied to compute the probabilities of several astrophysically
relevant processes. We calculate the rates of photon decay and vacuum Cherenkov
radiation along with the cross sections of electron-positron pair production on
background radiation and in the Coulomb field. The latter process is essential
for detection of photon-induced air showers in the atmosphere.Comment: 23 pages, 1 figur
Prospective constraints on Lorentz violation from ultrahigh-energy photon detection
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.Comment: 6 pages, revtex; significant additions compared to the previous
versio