Related papers: Photon decay in UHE air showers: stringent bound o…
A major challenge in ground-based ultra-high-energy gamma-ray observations remains in discriminating sporadic gamma-ray signals from a huge background of cosmic-ray events. To achieve good discrimination power of gamma rays against protons,…
Various phenomena of physics beyond that of the Standard Model could occur at high scale. Ultra-high energy cosmic rays are the only particles available to explore scales above a few dozens of TeV. Although these explorations are much more…
The interaction of Ultra High Energy Cosmic Rays (UHECRs) with the atoms of the atmosphere can occur at center-of-mass energies that surpass 100 TeV, while present human-made accelerators go up to 13 TeV. Therefore it provides a unique…
Data from multiple experiments suggest that the current interaction models used in Monte Carlo simulations do not correctly reproduce the hadronic interactions in air showers produced by ultra-high-energy cosmic rays (UHECR), in particular…
Large scale airshower simulations around the GZK cutoff are performed. An extensive analysis of the behaviour of the various subcomponents of the cascade is presented. We focus our investigation both on the study of total and partial…
A quantitative analysis of model uncertainties for calculations of the maximum depth of proton-initiated extensive air showers (EAS) has been performed. Staying within the standard physics picture and using the conventional approach to the…
We discuss the electromagnetic collisions of high energy protons, pions and kaons with atmospheric nuclei. In particular, we use the equivalent photon approximation to estimate (i) the diffractive collisions where the projectile scatters…
This paper presents the highlights from the recent measurements of the energy spectrum, mass composition, and arrival directions of the ultra-high energy ($> 10^{17}$ eV = 0.1 EeV) cosmic rays (UHECR) by the Pierre Auger Observatory. The…
The existence of extra degrees of freedom beyond the electroweak scale may allow the formation of black holes in nearly horizontal neutrino air showers. In this paper we examine the average properties of the light descendants of these black…
The details of Cerenkov light produced by a gamma ray or a cosmic ray incident at the top of the atmosphere is best studied through systematic simulations of the extensive air showers. Recently such studies have become all the more…
An investigation is performed of the Lorentz-violating electrodynamics extracted from the renormalizable sector of the general Lorentz- and CPT-violating standard-model extension. Among the unconventional properties of radiation arising…
We consider the possibility that Lorentz violation can generate differences between the limiting velocities of light and charged matter. Such effects would lead to efficient vacuum Cherenkov radiation or rapid photon decay. The absence of…
Both the lack of observation of ultra-high energy (UHE) photons and the limitations of the state-of-the-art methodology being applied for their identification motivate studies on alternative approaches to the relevant simulations and the…
We study the feasibility of detecting preshower initiated by ultra-high energy photons using Monte-Carlo simulations of nearly horizontal air showers for the example of the La Palma site of the Cherenkov Telescope Array. We investigate the…
We present new two-sided constraints on Lorentz Invariance violation energy scale for photons with quartic dispersion relation from recent gamma ray observations by Tibet-AS$\gamma$ and LHAASO experiments. The constraints are based on the…
We investigate the propagation of ultraheavy (UH) nuclei as ultrahigh-energy cosmic rays (UHECRs). We show that their energy loss lengths at $\lesssim300$ EeV are significantly longer than those of protons and intermediate-mass nuclei, and…
Coherent radiation at radio frequencies from high-energy showers fully contained in a dense radio-transparent medium - like ice, salt or regolith - has been extensively investigated as a promising technique to search for ultra-high energy…
Using data from inclined events ($60^{\circ}<\theta<80^{\circ}$) recorded by the Haverah Park shower detector, we show that above 10^19 eV less than 30% of the primary cosmic rays can be photons or iron nuclei at the 95% confidence level.…
The fluorescence technique has been successfully used to detect ultrahigh energy cosmic rays by indirect measurements. The underlying idea is that the number of charged particles in the atmospheric shower, i.e, its longitudinal profile, can…
We argue that the increase of the ratio baryon/meson due to the presence of strong colour fields and percolation in ultra-high energy hadronic collisions, helps to explain some of the global features of ultra-high energy cosmic ray cascades…