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P. G. Tinyakov

Publications and source records attributed to P. G. Tinyakov.

At least 37 records · Page 2Linked to original sources
arXiv2001

Tracing protons through the Galactic magnetic field: a clue for charge composition of ultra-high energy cosmic rays

We reconstruct the trajectories of ultra-high energy cosmic rays (UHECR) - observed by the AGASA experiment - in the Galactic magnetic field assuming that all particles have the same charge. We then study correlations between the reconstructed events and BL Lacs. The correlations have significance below 10^{-3} in the case of particles with charge +1. In the case of charge -1 the correlations are absent. We interpret this as evidence that protons are present in the flux of UHECR. Observed correlation provides an independent evidence that BL Lacs emit UHECR.

astro-ph↗
arXiv2001

BL Lacertae are probable sources of the observed ultra-high energy cosmic rays

We calculate angular correlation function between ultra-high energy cosmic rays (UHECR) observed by Yakutsk and AGASA experiments, and most powerful BL Lacertae objects. We find significant correlations which correspond to the probability of statistical fluctuation less than $10^{-4}$, including penatly for selecting the subset of brightest BL Lacs. We conclude that some of BL Lacs are sources of the observed UHECR and present a list of most probable candidates.

astro-ph↗
arXiv2001

Correlation function of ultra-high energy cosmic rays favors point sources

We calculate the angular two-point correlation function of ultra-high energy cosmic rays (UHECR) observed by AGASA and Yakutsk experiments. In both data sets, there is a strong signal at highest energies, which is concentrated in the first bin of the size of the angular resolution of the experiment. For the uniform distribution of sources, the probability of a chance clustering is 4 x 10^{-6}. Correlations are absent or not significant at larger angles. This favors the models with compact sources of UHECR.

astro-ph↗
arXiv2001

Violation of Lorentz Invariance and neutral component of UHECR

The observed clustering of ultra-high energy cosmic rays suggests the existence of a neutral component. The models with violation of Lorentz invariance may explain this component by neutrons becoming stable above some threshold energy E_0. The protons, in turn, may become unstable above some energy E_1>E_0. We calculate the dependence of the threshold energies E_0 and E_1 on the parameters of the model and find E_1/E_0\gsim 1.5. We argue that the characteristic threshold behavior of charged and neutral components may be used as the specific signature of models with violation of Lorentz invariance. The existence of the neutron stability threshold E_0 can be investigated with already existing data.

astro-ph↗
arXiv2000

Instanton propagator and instanton induced processes in scalar model

The propagator in the instanton background in the $(- λϕ^{4})$ scalar model in four dimensions is studied.Leading and sub-leading terms of its asymptotics for large momenta and its on-shell double residue are calculated analytically. These results are applied to the analysis of the initial-state and initial-final-state corrections and the calculation of the next-to-leading (propagator) correction to the exponent of the cross section of instanton induced multiparticle scattering processes.

hep-ph↗
arXiv2000

Is the electric charge conserved in brane world?

We discuss whether electric charge conservation may not hold in four-dimensional world in models with infinite extra dimensions, i.e., whether escape of charged particles from our brane is consistent with effectively four-dimensional electrodynamics on the brane. We introduce a setup with photon localized on the brane and show that charge leakage into extra dimension is allowed within this setup. The electric field induced on the brane by escaping charge does not obey four-dimensional Maxwell's equations; this field gradually disappears in a causal way. We also speculate on the possibility of the escape of colored particles and formation of colorless free quark states on the brane.

hep-ph↗
arXiv2000

Statistics of clustering of ultra-high energy cosmic rays and the number of their sources

Observation of clustering of ultra-high energy cosmic rays (UHECR) suggests that they are emitted by compact sources. Assuming small deflection of UHECR during the propagation, the statistical analysis of clustering allows to estimate the spatial density of the sources, h, including those which have not yet been observed directly. When applied to astrophysical models involving extra-galactic sources, the estimate based on 14 events with energy E>10^{20} eV gives h ~ 6 X 10^{-3} Mps^{-3}. With increasing statistics, this estimate may lead to exclusion of the models which associate the production of UHECR with exceptional galaxies such as AGN, powerful radio-galaxies, dead quasars, and models based on gamma ray bursts.

astro-ph↗
arXiv2000

Brane world: disappearing massive matter

In a brane (domain wall) scenario with an infinite extra dimension and localized gravity, bulk fermions and scalars often have bound states with zero 4-dimensional mass. In this way massless matter residing on the brane may be obtained. We consider what happens when one tries to introduce small, but non-vanishing mass to these matter fields. We find that the discrete zero modes turn into quasi-localized states with finite 4-dimensional mass and finite width. The latter is due to tunneling of massive matter into extra dimension. We argue that this phenomenon is generic to fields that can have bulk modes. We also point out that in theories meant to describe massive scalars, the 4-dimensional scalar potential has, in fact, power-law behavior at large distances.

hep-th↗
arXiv2000

Instanton propagator in scalar model: exact expression and contribution to instanton induced processes

The propagator in the instanton background in the -lambda phi^4 scalar model in four dimensions is studied. Leading and sub-leading terms of its asymptotics for large momenta and its on-shell double residue are calculated. These results are applied to the analysis of the initial state and initial-final state corrections and the calculation of the next-to-leading (propagator) correction to the exponent of the cross section of multiparticle scattering processes.

hep-ph↗
arXiv1999

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.

astro-ph↗
arXiv1999

Generation of 10^15 - 10^17 eV photons by UHE CR in the Galactic magnetic filed

We show that the deep expected in the diffuse photon spectrum above the threshold of e+e- pair production, i.e., at energies 10^15 - 10^17 eV, may be absent due to the synchrotron radiation by the electron component of the extragalactic Ultra-High Energy Cosmic Rays (UHE CR) in the Galactic magnetic filed. The mechanism we propose requires small (less than 2x10^-12 G) extragalactic magnetic fields and large fraction of photons in the UHE CR. For a typical photon flux expected in top-down scenarios of UHE CR, the predicted flux in the region of the deep is close to the existing experimental limit. The sensitivity of our mechanism to the extragalactic magnetic field may be used to improve existing bounds on the latter by two orders of magnitude.

astro-ph↗
arXiv1999

Ruling out a higher spin field solution to the cosmological constant problem

We consider the modification of Newton's gravity law in Dolgov's higher spin models designed to compensate the cosmological constant. We find that the effective Planck mass is unacceptably large in these models. We also point out that the properties of gravitational waves are entirely different in these models as compared to general relativity.

hep-ph↗
arXiv1998

Propagator in the Instanton Background and Instanton-Induced Processes in Scalar Model

The cross section of the multiparticle scattering processes in the non-perturbative sector of the scalar -lambda * phi^4 model is studied within the semiclassical approximation. For this purpose the exact formula for the residue of the propagator in the instanton background is derived. The exponent of the cross section is calculated at small energies both analytically and numerically in the leading and next-to-leading orders in energy. The results are in agreement with the numerical calculations of ref.[1].

hep-ph↗
arXiv1998

Galactic anisotropy of Ultra-High Energy Cosmic Rays produced by CDM-related mechanisms

We briefly review current theoretical and experimental status of Ultra-High Energy Cosmic Rays. We show that ``top-down'' mechanisms of UHE CR which involve heavy relic particle-like objects predict Galactic anisotropy of highest energy cosmic rays at the level of minimum $\sim 20%$. This anisotropy is large enough to be either observed or ruled out in the next generation of experiments.

hep-ph↗
arXiv1998

Cosmology with non-minimal scalar field: graceful entrance into inflation

We propose a scenario of the beginning of inflation in which the non-vacuum value of the scalar field that drives inflation develops dynamically due to the non-minimal coupling to gravity. In this scenario, inflation emerges as an intermediate stage of the evolution of the Universe, well after the Planck epoch, from a fairly general initial state.

hep-ph↗
arXiv1998

Signatures of Supersymmetric Q-Balls

In many supersymmetric extensions of the Standard Model the spectrum of states contains stable non-topological solitons, Q-balls. If formed in the Early Universe in sufficient amounts, Q-balls now contribute to cold dark matter. We discuss their experimental signatures and astrophysical implications.

hep-ph↗
arXiv1998

Experimental signatures of supersymmetric dark-matter Q-balls

Theories with low-energy supersymmetry predict the existence of stable non-topological solitons, Q-balls, that can contribute to dark matter. We discuss the experimental signatures, methods of detection, and the present limits on such dark matter candidates.

hep-ph↗