Correlations and Charge Composition of UHECR without Knowledge of Galactic Magnetic Field

We develop a formalism which allows to study correlations of charged UHECR with potential sources without using any Galactic Magnetic Field (GMF) model. The method is free of subjective chose of parameters on which the significance of correlations depends strongly. We show that correlations of the AGASA dataset with BL Lacs (found previously after reconstruction of particle trajectories in a specific GMF) are present intrinsically and can be detected without reference to a particular model of magnetic field.Comment: To be published in the Proceedings of the 28th International Cosmic Ray Conferenc

Cuts and penalties: comment on "The clustering of ultra-high energy cosmic rays and their sources"

In a series of papers we have found statistically significant correlations between arrival directions of ultra-high energy cosmic rays and BL Lacertae objects. Recently, our calculations were partly repeated by Evans, Ferrer and Sarkar with different conclusions. We demonstrate that the criticism of Evans, Ferrer and Sarkar is incorrect. We also present the details of our method.Comment: Replaced with version accepted for publication in Phys. Rev.

Sources of sub-GZK cosmic rays

We analyze the existing evidence that BL Lacertae objects (BL Lacs) are sources of the highest-energy cosmic rays. We argue that three independent signatures observed in the real data -- (1) improvement of correlations with corrections of trajectories for the Galactic magnetic field; (2) connection between gamma-ray and UHECR emissions; (3) non-uniform distribution of correlating rays over the sky -- are consistent with the hypothesis that a substantial fraction of cosmic rays in the energy range 40-60 EeV are protons accelerated in BL Lacs.Comment: Talk at the International Workshop on Extremely High Energy Cosmic Rays, November 5-6, 2002, RIKEN, Japa

Ultra-High Energy Cosmic Rays and Diffuse Photon Spectrum

It is argued that if extragalactic magnetic fields are smaller than 2x10^{-12} G the flux of ultra-high energy photons of (a few)x10^{-1} eV cm^{-2}s^{-1}sr^{-1} predicted in the top-down models of UHE CR implies similar flux of the diffuse photons in the energy range 10^{15}-10^{17} eV, which is close to the existing experimental limit.Comment: Talk given at XI Rencontres de Blois. 3 pages, no figure

Full sky harmonic analysis hints at large UHECR deflections

The full-sky multipole coefficients of the ultra-high energy cosmic ray (UHECR) flux have been measured for the first time by the Pierre Auger and Telescope Array collaborations using a joint data set with E > 10 EeV. We calculate these harmonic coefficients in the model where UHECR are protons and sources trace the local matter distribution, and compare our results with observations. We find that the expected power for low multipoles (dipole and quadrupole, in particular) is sytematically higher than in the data: the observed flux is too isotropic. We then investigate to which degree our predictions are influenced by UHECR deflections in the regular Galactic magnetic field (GMF). It turns out that the UHECR power spectrum coefficients $C_\ell$ are quite insensitive to the effects of the GMF, so it is unlikely that the discordance can be reconciled by tuning the GMF model. On the contrary, a sizeable fraction of uniformly distributed flux (representing for instance an admixture of heavy nuclei with considerably larger deflections) can bring simulations and observations to an accord.Comment: 8 pages, 4 figures and one table, JETPL style -- v2 as published in JETP

Instanton-Like Processes in Particle Collisions: a Numerical Study of the SU(2)-Higgs Theory below the Sphaleron Energy

We use semiclassical methods to calculate the probability of inducing a change of topology via a high-energy collision in the SU(2)-Higgs theory. This probability is determined by a complex solution to a classical boundary value problem on a contour in the complex time plane. In the case of small particle number it is the probability of instanton-like processes in particle collisions. We obtain numerically configurations with the correct topological features and expected properties in the complex time plane. Our work demonstrates the feasibility of the numerical approach to the calculation of instanton-like processes in gauge theories. We present our preliminary results for the suppression factor of topology changing processes, which cover a wide range of incoming particle numbers and energies below the sphaleron energy.Comment: 19 pages, 5 figures. To be published in proceedings of XI-th International School "Particles and Cosmology", Baksan, Russia 200

Cosmological attractors in massive gravity

We study Lorentz-violating models of massive gravity which preserve rotations and are invariant under time-dependent shifts of the spatial coordinates. In the linear approximation the Newtonian potential in these models has an extra ``confining'' term proportional to the distance from the source. We argue that during cosmological expansion the Universe may be driven to an attractor point with larger symmetry which includes particular simultaneous dilatations of time and space coordinates. The confining term in the potential vanishes as one approaches the attractor. In the vicinity of the attractor the extra contribution is present in the Friedmann equation which, in a certain range of parameters, gives rise to the cosmic acceleration.Comment: 26 pages, 1 figur

Star Wreck

Electroweak models with low-energy supersymmetry breaking predict the existence of stable non-topological solitons, Q-balls, that can be produced in the early universe. The relic Q-balls can accumulate inside a neutron star and gradually absorb the baryons into the scalar condensate. This causes a slow reduction in the mass of the star. When the mass reaches a critical value, the neutron star becomes unstable and explodes. The cataclysmic destruction of the distant neutron stars may be the origin of the gamma-ray bursts.Comment: 9 pages; references adde

Detection prospects of the Telescope Array hotspot by space observatories

In the present-day cosmic ray data, the strongest indication of anisotropy of the ultrahigh energy cosmic rays is the 20-degree hotspot observed by the Telescope Array with the statistical significance of 3.4\sigma. In this work, we study the possibility of detecting such a spot by space-based all-sky observatories. We show that if the detected luminosity of the hotspot is attributed to a physical effect and not a statistical fluctuation, the KLYPVE and JEM-EUSO experiments would need to collect ~300 events with E>57 EeV in order to detect the hotspot at the 5\sigma\ confidence level with the 68% probability. We also study the dependence of the detection prospects on the hotspot luminosity.Comment: 4 pages; v2: minor style changes to match the published versio