Microscopic Black Hole Production in TeV-Scale Gravity

Models with extra spatial dimensions and TeV-scale gravity offer the first opportunity to test the conjecture of black hole formation in trans-Planckian energy scattering with small impact parameters. After a brief review of gravitational scattering at ultrahigh energies and scenarios of TeV-scale gravity, search strategies at the LHC, at the Pierre Auger (cosmic ray) Observatory and at the neutrino telescopes AMANDA/IceCube are illustrated with the simplest but nevertheless representative example: production of Schwarzschild black holes and their observation via Hawking radiation in the large extra dimension scenario. Some more general features of the production of higher-dimensional black holes and/or uncertainties in the estimates are also outlined.Comment: 18 pages, 5 figures; Talk presented at XXX ITEP Winter School of Physics, Moscow, Russia, February 2002, references adde

"Exotic" quantum effects in the laboratory?

This Article provides a brief (non-exhaustive) review of some recent developments regarding the theoretical and possibly experimental study of "exotic" quantum effects in the laboratory with special emphasis on cosmological particle creation, Hawking radiation, and the Unruh effect.Comment: 5 page

Spectrum of Particles Created in Inhomogeneous Spacetimes

It is proved that the spectrum of scalar particles generated from the initial vacuum in inhomogeneous spacetime is nearly thermal in the limit of large momentum $k$, if the momentum was defined as the variable of the Fourier transform of the coordinate in the scalar field

Selfgravitating Gas Spheres in a Box and Relativistic Clusters: Relation between Dynamical and Thermodynamical Stability

We derive a variational principle for the dynamical stability of a cluster as a gas sphere in a box. Newtonian clusters are always dynamically stable and, for relativistic clusters, the relation between dynamical and thermodynamical instabilities is analyzed. The boundaries between dynamically and thermodynamically stable and unstable models are found numerically for relativistic stellar systems with different cut off parameters. A criterion based on binding energy curve is used for determination of the boundary of dynamical stability.Comment: 10 figure

Continuous Local Symmetry in Ising-type Models

A class of generalized Ising models is examined with a view to extracting a low energy sector comprising Dirac fermions coupled to Yang-Mills vectors. The main feature of this approach is a set of gap equations, covariant with respect to one of the $4$-dimensional crystallographic space groups.Comment: 7 pages, latex, IC/94/2

Heating of the intergalactic medium due to structure formation

We estimate the heating of the intergalactic medium due to shocks arising from structure formation. Heating of the gas outside the collapsed regions, with small overdensities (${n_b \over {\bar n_b}}\ll 200$) is considered here, with the aid of Zel'dovich approximation. We estimate the equation of state of this gas, relating the density with its temperature, and its evolution in time, considering the shock heating due to one-$\sigma$ density peaks as being the most dominant. We also estimate the mass fraction of gas above a given temperature as a function of redshift. We find that the baryon fraction above $10^6$ K at $z=0$ is $\sim 10$. We estimate the integrated Sunyaev-Zel'dovich distortion from this gas at present epoch to be of order $10^{-6}$.Comment: 5 pages (3 figs), To appear in MNRAS (pink pages

Origin of Correlations between Central Black Holes Masses and Galactic Bulge Velocity Dispersions

We argue that the observed correlations between central black holes masses M_{BH} and galactic bulge velocity dispersions \sigma_e in the form M_{BH}\propto\sigma_e^4 may witness on the pregalactic origin of massive black holes. Primordial black holes would be the centers for growing protogalaxies which experienced multiple mergers with ordinary galaxies. This process is accompanied by the merging of black holes in the galactic nuclei.Comment: 6 pages, 1 figure, submitted to Astron. and Astrophys. Transaction

The Cosmological Mean Density and its Local Variations Probed by Peculiar Velocities

Peculiar velocities thoughout the region of the local supercluster are reconstructed by two different orbit-retracing methods. The requirement of the optimal correlation between the radial components of reconstructed velocities and the observed peculiar velocities derived from our extensive new catalog of distances puts stringent constraints on the values of the cosmological parameters. Our constraints intersect those from studies of microwave background fluctuations and statistical properties of galaxy clustering: the ensemble of constraints are consistent with Omega_m=0.22\pm 0.02. While motions throughout the Local Supercluster provide a measure of the mean ratio of mass to light, there can be large local fluctuations. Our reconstruction of the infall velocities in the immediate vicinity of the Virgo Cluster shows that there is a mass-to-light anomaly of a factor of 3 to 6 between groups in the general field environment and the heavily populated Virgo Cluster.Comment: 4 pages, 2 figures, version to appear in Astrophysical Journal Letter

Astrophysical constraints on primordial black holes in Brans-Dicke theory

We consider cosmological evolution in Brans-Dicke theory with a population of primordial black holes. Hawking radiation from the primordial black holes impacts various astrophysical processes during the evolution of the Universe. The accretion of radiation by the black holes in the radiation dominated era may be effective in imparting them a longer lifetime. We present a detailed study of how this affects various standard astrophysical constraints coming from the evaporation of primordial black holes. We analyze constraints from the present density of the Universe, the present photon spectrum, the distortion of the cosmic microwave background spectrum and also from processes affecting light element abundances after nucleosynthesis. We find that the constraints on the initial primordial black hole mass fractions are tightened with increased accretion efficiency.Comment: 15 page

Coherent control of population transfer between communicating defects

Population transfer between two identical, communicating defects in a one-dimensional tight-binding lattice can be systematically controlled by external time-periodic forcing. Employing a force with slowly changing amplitude, the time it takes to transfer a particle from one defect to the other can be altered over several orders of magnitude. An analytical expression is derived which shows how the forcing effectively changes the energy splitting between the defect states, and numerical model calculations illustrate the possibility of coherent control of the transfer.Comment: 7 pages, 6 figures, to appear in Phys. Rev.