Roberto Aloisio

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The study of the interactions of Cosmic Rays (CR’s) with universal diffuse background radiation can provide very stringent tests of the validity of Special Relativity. The interactions we consider are the ones characterized by well defined energy thresholds whose energy position can be predicted on the basis of special relativity. We argue that the(More)
The dip is a feature in the diffuse spectrum of ultra-high energy (UHE) protons in the energy range 1×10−4×10 eV, which is caused by electron-positron pair production on the cosmic microwave background (CMB) radiation. For a power-law generation spectrum E, the calculated position and shape of the dip is confirmed with high accuracy by the spectra observed(More)
We present a detailed analytical study of the propagation of ultra high energy (UHE) particles in extragalactic magnetic fields. The crucial parameter which affects the diffuse spectrum is the separation between sources. In the case of a uniform distribution of sources with a separation between them much smaller than all characteristic propagation lengths,(More)
According to high resolution cold dark matter (CDM) simulations, large virialized halos are formed through the constant merging of smaller halos formed at earlier times. In particular, the halo of our Galaxy may have hundreds of dark matter clumps. The annihilation of dark matter particles such as the neutralino in these clumps generates γ-ray fluxes that(More)
Deformed or Doubly Special Relativity (DSR) [1, 2] can be understood as a tentative to modify Special Relativity (SR) in order to incorporate a new invariant scale other than that provided by the speed of light c. The idea driving this attempt is that quantum gravity effects seems to introduce a new dimensional fundamental scale given by the Planck length(More)
Quantum gravitational effects may induce stochastic fluctuations in the structure of space-time, to produce a characteristic foamy structure. It has been known for some time now that these fluctuations may have observable consequences for the propagation of cosmic ray particles over cosmological distances. While invoked as a possible explanation for the(More)
We discuss the antiGZK effect in the diffusive propagation of ultra high energy protons in intergalactic magnetic fields, which consists in a jump-like increase of the maximum distance from which ultra high energy protons can reach an observer. The position of this jump, Ej ≈ 2 × 10 eV, is determined exclusively by energy losses (transition from adiabatic(More)