Quantum Dew

We consider phase separation in nonequilibrium Bose gas with an attractive interaction between the particles. Using numerical integrations on a lattice, we show that the system evolves into a state that contains drops of Bose-Einstein condensate suspended in uncondensed gas. When the initial gas is sufficiently rarefied, the rate of formation of this quantum dew scales with the initial density as expected for a process governed by two-particle collisions.Comment: 4 pages, revtex, 5 figure

Patterns from preheating

The formation of regular patterns is a well-known phenomenon in condensed matter physics. Systems that exhibit pattern formation are typically driven and dissipative with pattern formation occurring in the weakly non-linear regime and sometimes even in more strongly non-linear regions of parameter space. In the early universe, parametric resonance can drive explosive particle production called preheating. The fields that are populated then decay quantum mechanically if their particles are unstable. Thus, during preheating, a driven-dissipative system exists. In this paper, we show that a self-coupled inflaton oscillating in its potential at the end of inflation can exhibit pattern formation.Comment: 4 pages, RevTex, 6 figure

Heavy-to-heavy quark decays at NNLO

Details of a recent calculation of O(alpha_s^2) corrections to the decay b -> c,l,nu_l, taking into account the c-quark mass, are described. Construction of the expansion in the mass ratio m_c/m_b as well as the evaluation of new four-loop master integrals are presented. The same techniques are applicable to the muon decay, mu -> e,nu_mu,anti-nu_e. Analytical results are presented, for the physical cases as well as for a model with purely-vector couplings.Comment: 11 page

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.Comment: The version accepted for publication in Phys. Rev. Lett. Notations changed to conventional ones. The estimate of the effective GZK radius replaced by the result of numerical simulatio

Ab initio-based prediction and TEM study of silicide precipitation in titanium

In this work we applied our recently developed thermodynamic model to predict the structure of Ti-Si precipitates in α-Ti matrix of the Ti-Si alloy with total Si concentration of 0.7 wt.%. We considered all prominent Ti-Si phases such as Ti₃Si; Ti₅Si₃; Ti₅Si₄; TiSi and two TiSi₂ phases and discovered that formation of the Ti₅Si₃ phase is more favorable than that of the Ti₃Si in contradiction with the known phase diagrams. Theoretical result was confirmed by experimental investigation of microstructure and phase composition of the model Ti-0.7Si alloy annealed at 873 K for 10 h. Indeed, the only observed phase has hexagonal Ti₅Si₃ structure. To ensure the completeness of the results we calculated ab initio elastic constants for all considered Ti-Si phase

Constrained Simulations of the Magnetic Field in the Local Universe and the Propagation of UHECRs

We use simulations of LSS formation to study the build-up of magnetic fields (MFs) in the ICM. Our basic assumption is that cosmological MFs grow in a MHD amplification process driven by structure formation out of a seed MF present at high z. Our LCDM initial conditions for the density fluctuations have been statistically constrained by the observed galaxies, based on the IRAS 1.2-Jy all-sky redshift survey. As a result, prominent galaxy clusters in our simulation coincide closely with their real counterparts. We find excellent agreement between RMs of our simulated clusters and observational data. The improved resolution compared to previous work also allows us to study the MF in large-scale filaments, sheets and voids. By tracing the propagation of UHE protons in the simulated MF we construct full-sky maps of expected deflection angles of protons with arrival energies E=1e20eV and 4e19eV, respectively. Strong deflections are only produced if UHE protons cross clusters, however covering only a small area on the sky. Multiple crossings of sheets and filaments over larger distances may give rise to noticeable deflections, depending on the model adopted for the magnetic seed field. Based on our results we argue that over a large fraction of the sky the deflections are likely to remain smaller than the present experimental angular sensitivity. Therefore, we conclude that forthcoming air shower experiments should be able to locate sources of UHE protons and shed more light on the nature of cosmological MFs.Comment: 3revised version, JCAP, accepte