Observational physics of mirror world

The existence of the whole world of shadow particles, interacting with each other and having no mutual interactions with ordinary particles except gravity is a specific feature of modern superstring models, being considered as models of the theory of everything. The presence of shadow particles is the necessary condition in the superstring models, providing compensation of the asymmetry of left and right chirality states of ordinary particles. If compactification of additional dimensions retains the symmetry of left and right states, shadow world turns to be the mirror one, with particles and fields having properties strictly symmetrical to the ones of corresponding ordinary particles and fields. Owing to the strict symmetry of physical laws for ordinary and mirror particles, the analysis of cosmological evolution of mirror matter provides rather definite conclusions on possible effects of mirror particles in the universe. A general qualitative discussion of possible astronomical impact of mirror matter is given, in order to make as wide as possible astronomical observational searches for the effects of mirror world, being the unique way to test the existence of mirror partners of ordinary particles in the Nature

Pion Decay Constant at Finite Temperature in the Nonlinear Sigma Model

We calculate the pion decay constant near the critical temperature of the $O(N)$ nonlinear sigma model in the large $N$ limit. Making use of the known low temperature behavior, we construct a Pad\'{e} approximant to obtain the behavior of $f_\pi(T)$ at all temperatures.Comment: 8 pages, one latex file and one postscript file (uses psfig). Uuencode

Archimedean-type force in a cosmic dark fluid: II. Qualitative and numerical study of a multistage Universe expansion

In this (second) part of the work we present the results of numerical and qualitative analysis, based on a new model of the Archimedean-type interaction between dark matter and dark energy. The Archimedean-type force is linear in the four-gradient of the dark energy pressure and plays a role of self-regulator of the energy redistribution in a cosmic dark fluid. Because of the Archimedean-type interaction the cosmological evolution is shown to have a multistage character. Depending on the choice of the values of the model guiding parameters,the Universe's expansion is shown to be perpetually accelerated, periodic or quasiperiodic with finite number of deceleration/acceleration epochs. We distinguished the models, which can be definitely characterized by the inflation in the early Universe, by the late-time accelerated expansion and nonsingular behavior in intermediate epochs, and classified them with respect to a number of transition points. Transition points appear, when the acceleration parameter changes the sign, providing the natural partition of the Universe's history into epochs of accelerated and decelerated expansion. The strategy and results of numerical calculations are advocated by the qualitative analysis of the instantaneous phase portraits of the dynamic system associated with the key equation for the dark energy pressure evolution.Comment: 15 pages, 12 figures, Part II, typos corrected, Fig.4 replaced, references correcte

Synthesis, characterization and photophysical properties of new cyclometallated platinum(II) complexes with pyrazolonate ancillary ligand

New cyclometalated platinum(II) complexes with pyrazolonate ancillary ligand (ppy)Pt(pmip) (1) and (dfppy)Pt(pmip) (2) (ppy = 2-phenylpyridine, dfppy = (4,6-difluorophenyl)pyridine, Hpmip = 1-phenyl-3-methyl-4-isobutyryl-5- pyrazolone) were synthesized and structurally characterized. Both compounds revealed square-planar geometry. The crystal cell of 1 was found to contain the monomer molecules of platinum compound whereas dimer molecules of 2 with short Pt⋯Pt contacts of 3.2217(3) were observed in the crystal cell of 2. Photophysical properties of 1 and 2 were investigated in detail. The highly resolved photoluminesence spectra of the platinum complexes in solution contain emission bands in the region of 470-550 nm attributed to monomer compounds 1 and 2. The triplet-state energies of 1 and 2 obtained from DFT calculations agree very well with the experimental data. In the crystalline state complex 2 revealed excimer emission as a structureless broad band at ca. 584 nm related to dimer molecules of platinum compound presented in the crystals. © 2013 Elsevier B.V. All rights reserved

Infrared afterglow of GRB041219 as a result of reradiation on dust in a circumstellar cloud

Observations of gamma ray bursts (GRB) afterglows in different spectral bands provide a most valuable information about their nature, as well as about properties of surrounding medium. Powerful infrared afterglow was observed from the strong GRB041219. Here we explain the observed IR afterglow in the model of a dust reradiation of the main GRB signal in the envelope surrounding the GRB source. In this model we do not expect appearance of the prompt optical emission which should be absorbed in the dust envelope. We estimate the collimation angle of the gamma ray emission, and obtain restrictions on the redshift (distance to GRB source), by fitting the model parameters to the observational data.Comment: 6 pages, 2 figures, Submited to Astrofizik

The Zipf law for random texts with unequal probabilities of occurrence of letters and the Pascal pyramid

We model the generation of words with independent unequal probabilities of occurrence of letters. We prove that the probability $p(r)$ of occurrence of words of rank $r$ has a power asymptotics. As distinct from the paper published earlier by B. Conrad and M. Mitzenmacher, we give a brief proof by elementary methods and obtain an explicit formula for the exponent of the power law.Comment: 4 page

Population synthesis of old neutron stars in the Galaxy

The paucity of old isolated accreting neutron stars in ROSAT observations is used to derive a lower limit on the mean velocity of neutron stars at birth. The secular evolution of the population is simulated following the paths of a statistical sample of stars for different values of the initial kick velocity, drawn from an isotropic Gaussian distribution with mean velocity $0\leq < V>\leq 550$ ${\rm km s^{-1}}$. The spin-down, induced by dipole losses and the interaction with the ambient medium, is tracked together with the dynamical evolution in the Galactic potential, allowing for the determination of the fraction of stars which are, at present, in each of the four possible stages: Ejector, Propeller, Accretor, and Georotator. Taking from the ROSAT All Sky Survey an upper limit of $\sim 10$ accreting neutron stars within $\sim 140$ pc from the Sun, we infer a lower bound for the mean kick velocity, \ga 200-300 ${\rm km s^{-1}}$. The same conclusion is reached for both a constant ($B\sim 10^{12}$ G) and a magnetic field decaying exponentially with a timescale $\sim 10^9$ yr. Present results, moreover, constrain the fraction of low velocity stars, which could have escaped pulsar statistics, to \la 1%.Comment: 8 pages, 4 PostScript figures, to appear in the proceedings of IAU Symposium 19

Optical "fingerprints" of dielectric resonators

The complete picture of the optical properties of resonant structures, along with the frequency, quality factor, and line shape in the scattering spectra, is determined by the electromagnetic field distribution patterns, which are a kind of "fingerprint" of each resonant eigenmode. In this paper, we simultaneously analyze the changes in the spectra and the transformation of the field pattern during the topological transitions from a thin disk to a ring with a gradually increasing thickness and further to a split ring. In addition, we demonstrate characteristic optical fingerprints for well-known interference effects such as bound states in the continuum and Fano resonances.Comment: 11 pages, 5 figure

Thermally stable composite system Al2O3-Ce 0.75Zr0.25O2 for automotive three-way catalysts

Present-day three-way catalysts operate in contact with exhaust gases whose temperature is as high as &gt;1000 C, so the problem of developing thermally stable catalytic compositions is still topical. A series of Al2O 3-Ce0.75Zr0.25O2 composites containing 0, 10, 25, and 50 wt % Al2O3 has been synthesized by direct precipitation. The as-prepared composites and those calcined in air at 1000 and 1100 C have been characterized by BET, X-ray diffraction, transmission electron microscopy, and temperature-programmed reduction methods. The composites aged at 1050 C in a 2% O2 + 10% H2O + 88% N2 atmosphere have been used to prepare monolith catalysts, and the oxygen storage capacity (OSC) of the latter has been measured using a gas analysis setup. As the proportion of Al2O 3 in the composite is raised, the mixing uniformity and degree of dispersion of Ce x Zr1-x O2-δ particles increase, their chemical composition becomes homogeneous, and the amount of cerium involved in oxidation and reduction increases. The composite containing 50 wt % Al2O3 is a mixture of Ce x Zr 1-x O2-δ and Al2O3 crystallites, whose size is practically unaffected by calcination. The (Pt/Al2O3 + Al2O3-Ce 0.75Zr0.25O2) based on this composite has the highest OSC and is the most active. For this reason, full-scale testing of this catalyst is recommended. © 2013 Pleiades Publishing, Ltd