arXiv subjects
Publications and source records attributed to Ramon Toldra.
We calculate the cosmic ray spectrum of ultra high energy neutralinos that one should expect provided that the observed ultra high energy cosmic rays are produced by the decay of superheavy particles X, M_X>10^{12} GeV, in supersymmetric models. Our calculation uses an extended DGLAP formalism. Forthcoming cosmic ray observatories should be able to detect these neutralinos.
We calculate the spectrum of ultra high energy cosmic rays produced by the decay of a superheavy dark matter population clustered in the galactic halo. To perform this calculation we start with fragmentation functions measured at LEP and evolve them to the cosmic ray energy scale using the QCD DGLAP equations. We consider Standard Model evolution and supersymmetric evolution. We also take into account many-body final states in the decay of the dark matter particles.
We solve numerically the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations for the evolution of fragmentation functions using the Laguerre method. We extend this method to include supersymmetric evolution. The solution to the DGLAP equations is particularly interesting to calculate the expected spectra of Ultra High Energy Cosmic Rays in models where they are produced by the decay of a massive particle X, M_X > 10^{12} GeV.
It has been speculated that the recently detected ultra-high energy cosmic rays may originate from the decays of relic particles with mass of order $10^{12}$ GeV clustered in the halo of our Galaxy. This hypothesis can be tested through forthcoming measurements of the spectra of both high energy cosmic nucleons and neutrinos, which are determined in this model by the physics of QCD fragmentation, with no astrophysical uncertainties. We evolve fragmentation spectra measured at LEP energies up to the scale of the decaying particle mass by numerical solution of the DGLAP equations. This enables incorporation of the effects of supersymmetry on the development of the cascade and we also allow for decays into many-particle states. The calculated spectral shape agrees well with present cosmic ray data beyond the Greisen-Zatsepin-Kuzmin energy.
We obtain the photon spectrum induced by a cosmic background of unstable neutrinos. We study the spectrum in a variety of cosmological scenarios and also we allow for the neutrinos having a momentum distribution (only a critical matter dominated universe and neutrinos at rest have been considered until now). Our results can be helpful when extracting bounds on neutrino electric and magnetic moments from cosmic photon background observations.
It has been recently suggested that magnetically affected neutrino oscillations inside a cooling protoneutron star, created in a supernova explosion, could explain the large proper motion of pulsars. We investigate whether this hypothesis is in agreement with the observed properties of pulsars and find that present data disfavor the suggested mechanism. The relevance of our results for other models proposed to understand the origin of pulsar velocities is also discussed.
We obtain new stringent constraints on a light spinless particle phi coupled only to photons at low energies, considering its effects on the extragalactic photon background, the blackbody spectrum of the CMBR and the cosmological abundance of deuterium.