Reheating a multi-throat universe by brane motion

We propose a mechanism of reheating after inflation in multi-throat scenarios of warped extra dimensions. Validity of an effective field theory on the standard model (SM) brane requires that the position of the SM brane during inflation be different from the position after inflation. The latter is supposed to be near the tip of the SM throat but the former is not. After inflation, when the Hubble expansion rate becomes sufficiently low, the SM brane starts moving towards the tip and eventually oscillates. The SM fields are excited by the brane motion and the universe is reheated. Since interaction between the brane position modulus and the SM fields is suppressed only by the local string scale, the modulus effectively decays into the SM fields.     

Understanding the magnetocatalytic effect: magnetism as a driving force for surface segregation

The magnetocatalytic (or Hedvall) effect refers to a change in the rate of a chemical reaction on a magnetic surface at the Curie point T(C). For Ni catalysts, experiments suggest the effect is related to a sudden increase in segregated surface C, a strong catalytic poison, at temperatures below T(C). However, the connection between magnetism and surface segregation is not understood. Using density functional theory and spin-dynamics simulations, we show that the solubility of C in Ni is significantly reduced in the ferromagnetic state, because C suppresses Ni magnetism and thereby increases the heat of solution. This explains the observed increase in C segregation and the reduced catalytic activity below T(C).     

Berry curvature on the fermi surface: anomalous Hall effect as a topological fermi-liquid property

The intrinsic anomalous Hall effect in metallic ferromagnets is shown to be controlled by Berry phases accumulated by adiabatic motion of quasiparticles on the Fermi surface, and is purely a Fermi-liquid property, not a bulk Fermi sea property like Landau diamagnetism, as has been previously supposed. Berry phases are a new topological ingredient that must be added to Landau Fermi-liquid theory in the presence of broken inversion or time-reversal symmetry.     

Reheating and leptogenesis in a SUGRA inspired brane inflation

We have studied extensively phenomenological implications in a specific model of brane inflation driven by background supergravity (Choudhury and Pal, 2011) [1], via thermal history of the universe and leptogenesis pertaining to the particle physics phenomenology of the early universe. Using the one loop corrected inflationary potential we have investigated for the analytical expression as well as the numerical estimation for brane reheating temperature for standard model particles. This results in some novel features of reheating from this type of inflation which have serious implications in the production of heavy Majorana neutrinos needed for leptogenesis through the reheating temperature. We have also derived the expressions for the gravitino abundance during reheating and radiation dominated era. We have further estimated different parameters at the epoch of phase transition and revealed their salient features. At the end we have explicitly given an estimate of the amount of CP violation through the effective CP phase which is related to baryon asymmetry as well as gravitino dark matter abundance.     

The nuclear surface as a collective variable

In heavy nuclei where the thickness of the diffused edge is relatively small, a certain sharp effective surface can be defined which characterizes the shape of the nucleus, and it can be considered as a collective dynamic variable. It is shown that the problem of fluid dynamics can be simplified by reducing it to simple linearized equations for the dynamics in the nuclear interior and boundary conditions set at the effective dynamic sharp surface of the density distribution. These conditions are derived from the fluid dynamical equations. Transitional densities obtained from this simple model are compared with the numerical solution of fluid dynamical equations.     

Electromagnetism as a second-order effect

The Electric and Magnetic Fields of a charge moving with uniform velocity are derived from Coulomb's law taking the transformations of the Special Theory of Relativity as axiomatic.     

The Brewster effect for a one-dimensional random surface

By the use of a unitarity and reciprocity conserving theory for the scattering of p-polarized light from a one-dimensional random dielectric surface the we determine the shift in the Brewster angle toward smaller angles of incidence caused by the surface roughness, and the (non-zero) value of the reflectivity at its minimum. Both quantities may be useful in the characterization of the roughness of such surfaces.     

Aharonov-Bohm effect for electrons on a liquid-helium surface

A method for obtaining finite electronic systems on a liquid-helium surface is proposed. If a thin film of liquid helium lies above a bottom capacitor plate made in the form of metal rings connected with one another, then electrons will accumulate in potential troughs near these rings. The purity of the helium surface, i.e., the absence of impurities and pinning centers on it, affords an excellent opportunity for investigating the Aharonov-Bohm effect in an ideal ring of a Wigner crystal and a Luttinger liquid Pis’ma Zh. éksp. Teor. Fiz. 67, No. 6, 410–414 (25 March 1998)     

The Brewster effect for a one-dimensional random surface

Abstract

By the use of a unitarity and reciprocity conserving theory for the scattering of p-polarized light from a one-dimensional random dielectric surface the we determine the shift in the Brewster angle toward smaller angles of incidence caused by the surface roughness, and the (non-zero) value of the reflectivity at its minimum. Both quantities may be useful in the characterization of the roughness of such surfaces.     

Resonant surface plasmons of a metal nanosphere treated as propagating surface plasmons

On the assumption that the resonant surface plasmons on a spherical nanoparticle are formed by standing waves of two counter-propagating surface plasmon waves along the surface, by using Mie theory simulation, we find that the dispersions of surface plasmon resonant modes supported by silver nanospheres match with those of the surface plasmons on a semiinfinite medium-silver interface very well. This suggests that the resonant surface plasmons of a metal nanosphere can be treated as a propagating surface plasmon wave.     

Sound generation as a drop falls on a water surface

Impact of a drop on a water surface is accompanied by a series of sound pulses propagating in air and underwater. Depending on the falling mode (drop size and initial velocity), pulses substantially differ in amplitude, duration, and modulation frequency. We study falling modes in which in addition to conventional sound packets—the shock pulse and single resonance sound packets—several packets are observed. Experiments were conducted with simultaneous recording of sound in air and underwater and were accompanied by synchronous video depiction of currents in the drop impact region. Comparison of videograms and phonograms demonstrate that the sources of sound packets are gas cavities of arbitrary shape detached from the underwater cavern under the action of large accelerations (several km/s²) during a sharp change in its surface area, which gradually achieve equilibrial elliptical and spherical shapes.     

Mixed valence as a polaronic effect

A theory of intermediate valence, based on a reformulation of the adiabatic approximation which treats the electron-phonon interaction nonperturbatively, is presented. Without assuming a specific model we show that a narrow quasi-degenerate f-band above the Fermi level becomes unstable. Due to electron-phonon coupling it collapses giving rise to mixed valent configurations, depending on the location of the f-level relative to the Fermi sea. Phenomenological implications are illustrated by a simple model.     

Electromagnetism as a second order effect

An historical survey of the theories of the forces between current elements is given and Ampère's formula is compared with the Biot-Savart law. It is shown that the Biot-Savart law, in differential form, is consistent with both Classical Electromagnetism and the Special Theory of Relativity.     

Neutrons scattering as a method for fermi surface investigations

High-T_c A15-compounds are suggested as suitable materials for which Fermi surface investigations by means of thermal neutron scattering might be possible. The structure of the differential neutron—d-electron cross section at small scattering angles is connected in a simple way with parameters defining the Fermi surface of the linear chain model. The magnitude of the cross section is estimated are compared with the phonon background.     

Graphene as a quantum surface with curvature-strain preserving dynamics

We discuss how the curvature and the strain density of an atomic lattice generate the quantization of graphene sheets as well as the dynamics of geometric quasiparticles propagating along the constant curvature/strain levels. The internal kinetic momentum of a Riemannian oriented surface (a vector field preserving the Gaussian curvature and the area) is determined.