相关论文: Stable Superstring Relics and Ultrahigh Energy Cos…
Transrelativistic supernovae (SNe), which are likely driven by central engines via jets or winds, have been among candidate sources of ultrahigh-energy cosmic rays (UHECRs). We investigate acceleration and survival of UHECR nuclei in the…
Special relativity has been tested at low energy with great accuracy, but its extrapolation to very high-energy phenomena is much less well established. Introducing a critical distance scale, a , below 10E-25 cm (the wavelength scale of the…
Up to date, there is no consensus regarding the origin of ultra-high energy cosmic rays (UHECR) beyond the Greisen--Zatsepin--Kuzmin (GZK) limit. In order for these UHECRs to reach the Earth, an extremely suppressed interaction between them…
The recently observed ultra-high energy (UHE) cosmic rays beyond the Greisen-Zatsepin-Kuzmin bound can be explained by the decays of some superheavy $X$ particles forming a part of dark matter in our universe. We consider various discrete…
Many extensions of the Standard Model have to face the problem of new unsuppressed baryon-number violating interactions. In supersymmetry, the simplest way to solve this problem is to assume R-parity conservation. As a result, the lightest…
Stable, quantized gravitational bound states of primordial black holes called Holeums could have been produced in the early universe and could be a component of the Super Heavy Dark Matter (SHDM) present in galactic halos. We show that…
The rarest cosmic rays above the GZK cut'off $(E_{CR} \tilde{>} 10^{19} \div 10^{20} eV)$ are probably born at cosmic distances ($\tilde{>}$ tens Mpc) by AGNs (QSRs, BLac, Blazars...). Their puzzling survival over $2.75 K^o$ BBR radio waves…
Realistic superstring models generically give rise to exotic matter states, which arise due to the ``Wilson-line'' breaking of the non-Abelian unifying gauge symmetry. Often such states are protected by a gauge or local discrete symmetry…
Rapidly-spinning magnetars can potentially form by the accretion induced collapse of a white dwarf or by neutron star mergers if the equation of state of nuclear density matter is such that two low mass neutron stars can sometimes form a…
Recent evidence from the Pierre Auger Observatory suggests a transition, at 5 EeV-10EeV in the composition of Ultra High Energy Cosmic Rays (UHECRs), from protons to heavier nuclei such as iron. I consider here the implications of the…
Perturbative gauge coupling unification in realistic superstring models suggests the existence of additional heavy down-type quarks, beyond the minimal supersymmetric standard model. The mass scale of the heavy down-type quarks is…
Ultra High Energy Cosmic Rays, UHECR, are charged particles with energies between $\sim10^{18}\,{\rm eV}$ and $\sim3\times10^{20}\,{\rm eV}\sim50\,{\rm J}$. They exhibit fundamental physics at energies inaccessible to terrestrial…
The Fermi Large Area Telescope (Fermi LAT) collaboration has recently reported on 50 months of measurements of the isotropic Extragalactic Gamma Ray Background (EGRB) spectrum between $100\mbox{MeV}$ and $820\mbox{GeV}$. Ultrahigh Energy…
The Ultra High Energy Cosmic Ray UHECR, by UHE neutrino-relic neutrino Z showering in Hot Dark Halos HDM, should exhibits an energy spectra and an anisotropy reflecting (also) the relic neutrino masses and their hierarchical HDM halo…
The Exceptional Supersymmetric Standard Model (E$_6$SSM) is a low energy alternative to the MSSM with an extra $U(1)$ gauge symmetry and three generations of matter filling complete 27-plet representations of $E_6$. This provides both new D…
We investigate the possibility that ultra-high energy cosmic rays (UHECRs) originate from the annihilation of relic superheavy (SH) dark matter in the Galactic halo. In order to fit the data on UHECRs, a cross section of $<\sigma_Av>\sim…
The origin and composition of ultra-high-energy cosmic rays (UHECRs) remain a mystery. The proton dip model describes their spectral shape in the energy range above $10^9$ GeV by pair production and photohadronic interactions with the…
If Ultra High Energy Cosmic Rays (UHECRs) with E>4 10^{19} eV originate from BL Lacertae at cosmological distances as suggested by recent studies, the absence of the GZK cutoff can not be reconciled with Standard-Model particle properties.…
The conjecture that ultra high energy cosmic rays (UHECRs) are actually strangelets is discussed. Besides the reason that strangelets can do as cosmic rays beyond the GZK-cutoff, another argument to support the conjecture is addressed in…
We outline two concepts to explain Ultra High Energy Cosmic Rays (UHECRs), one based on radio galaxies and their relativistic jets and terminal hot spots, and one based on relativistic Super-Novae (SNe) or Gamma Ray Bursts (GRBs) in…