Speaker
Description
Lorentz Invariance Violation (LIV) can be studied in various sectors of
high-energy particle physics. Since its effects are predicted to
increase with energy, ultra-high energy cosmic rays and gamma rays are
powerful probes for testing different LIV models. In this work, the
unprecedented statistics and data quality collected by the Pierre Auger
Observatory in the EeV range are used to explore LIV scenarios. A
phenomenological approach of LIV is considered by introducing a generic
modification of the energy dispersion relation of the particles, which
is compatible with the Coleman and Glashow approach. This may affect the
kinematics of the interactions in the extragalactic propagation and in
the shower development in the atmosphere. To test this, a fit of the
spectrum and composition observables considering LIV in the propagation
of nuclei is used as a tool to show the sensitivity of the data to LIV.
Also, under certain LIV assumptions for the GZK photons propagation, it
is possible to constrain the violation using the photon flux limits. For
the electromagnetic sector, while no constraints can be obtained in the
absence of protons beyond $10^{19}$ eV, we obtain $\delta_{\gamma,0} > -10^{-21}$,
$\delta_{\gamma,1} > -10^{-40} \ \mathrm{eV}^{-1}$ and $\delta_{\gamma,2} > -10^{-58} \
\mathrm{eV}^{-2}$ in the case of a subdominant proton component up to
$10^{20}$ eV. For the hadronic sector, we study the best description of
the data as a function of LIV coefficients and we derive constraints in
the hadronic sector such as $\delta_{\mathrm{had},0} < 10^{-19}$, $\delta_{\mathrm{had},1} < 10^{-38} \
\mathrm{eV}^{-1}$ and $\delta_{\mathrm{had}} < 10^{-57} \ \mathrm{eV}^{-2}$ at
5$\sigma$ CL.
