Vector Currents of Massive Neutrinos of an Electroweak Nature

The mass of an electroweakly interacting neutrino consists of the electric and weak parts responsible for the existence of its charge, charge radius, and magnetic moment. Such connections explain the formation of paraneutrinos, for example, at the polarized neutrino electroweak scattering by spinless nuclei. We derive the structural equations that relate the self-components of mass to charge, charge radius, and magnetic moment of each neutrino as a consequence of unification of fermions of a definite flavor. They indicate the availability of neutrino universality and require following its logic in a constancy law dependence of the size implied from the multiplication of a weak mass of neutrino by its electric mass. According to this principle, all Dirac neutrinos of a vector nature, regardless of the difference in their masses, have the same charge, an identical charge radius, as well as an equal magnetic moment. Thereby, the possibility appears of establishing the laboratory limits of weak masses of the investigated types of neutrinos. Finding estimates show clearly that the earlier measured properties of these particles may testify in favor of the unified mass structure of their interaction with any of the corresponding types of gauge fields.Comment: 14 pages, LaTex, Published version in CJ

The Minkowski metric in non-inertial observer radar coordinates

We give a closed expression for the Minkowski (1+1)-dimensional metric in the radar coordinates of an arbitrary non-inertial observer O in terms of O's proper acceleration. Knowledge of the metric allows the non-inertial observer to perform experiments in spacetime without making reference to inertial frames. To clarify the relation between inertial and non-inertial observers the coordinate transformation between radar and inertial coordinates, also is given. We show that every conformally flat coordinate system can be regarded as the radar coordinate system of a suitable observer for a suitable parametrization of the observer worldline. Therefore, the coordinate transformation between arbitrarily moving observers is a conformal transformation and conformally invariant (1+1)-dimensional theories lead to the same physics for all observers, independently of their relative motion.Comment: Revtex4, 6 pages, 1 figur

On the approach to equilibrium of an Hamiltonian chain of anharmonic oscillators

In this note we study the approach to equilibrium of a chain of anharmonic oscillators. We find indications that a sufficiently large system always relaxes to the usual equilibrium distribution. There is no sign of an ergodicity threshold. The time however to arrive to equilibrium diverges when $g \to 0$, $g$ being the anharmonicity.Comment: 8 pages, 5 figure

Finite size corrections to the radiation reaction force in classical electrodynamics

We introduce an effective field theory approach that describes the motion of finite size objects under the influence of electromagnetic fields. We prove that leading order effects due to the finite radius $R$ of a spherically symmetric charge is order $R^2$ rather than order $R$ in any physical model, as widely claimed in the literature. This scaling arises as a consequence of Poincar\'e and gauge symmetries, which can be shown to exclude linear corrections. We use the formalism to calculate the leading order finite size correction to the Abraham-Lorentz-Dirac force.Comment: 4 pages, 2 figure

Quadrupole-scissors modes and nonlinear mode coupling in trapped two-component Bose-Einstein condensates

We theoretically investigate quadrupolar collective excitations in two-component Bose-Einstein condensates and their nonlinear dynamics associated with harmonic generation and mode coupling. Under the Thomas-Fermi approximation and the quadratic polynomial ansatz for density fluctuations, the linear analysis of the superfluid hydrodynamic equations predicts excitation frequencies of three normal modes constituted from monopole and quadrupole oscillations, and those of three scissors modes. We obtain analytically the resonance conditions for the second harmonic generation in terms of the trap aspect ratio and the strength of intercomponent interaction. The numerical simulation of the coupled Gross-Pitaevskii equations vindicates the validity of the analytical results and reveals the dynamics of the second harmonic generation and nonlinear mode coupling that lead to nonlinear oscillations of the condensate with damping and recurrence reminiscent of the Fermi-Pasta-Ulam problem.Comment: 10 pages, 5 figures, revtex

Prediction of the derivative discontinuity in density functional theory from an electrostatic description of the exchange and correlation potential

We propose a new approach to approximate the exchange and correlation (XC) functional in density functional theory. The XC potential is considered as an electrostatic potential, generated by a fictitious XC density, which is in turn a functional of the electronic density. We apply the approach to develop a correction scheme that fixes the asymptotic behavior of any approximated XC potential for finite systems. Additionally, the correction procedure gives the value of the derivative discontinuity; therefore it can directly predict the fundamental gap as a ground-state property.Comment: 5 pages, 4 figure

Hi Spin Temperatures and Heating Requirements in Outer Regions of Disk Galaxies

ABSRACT:We show how to use 21-cm emission and absorption studies to estimate the heat inputs to the neutral gas in low pressure environments, such as in outer disks of spiral galaxies, in galactic halos or in intergalactic space. For a range of model parameters we calculate the gas kinetic and spin temperatures ($T_K$ and $T_S$) and the relation between $T_S$ and the heat input to the gas. We outline the conditions for a ``two phase medium'' to exist. We find that although $T_S$ can be much smaller than $T_K$, $T_S$ is always $\gg 3$ K for column densities greater that $5 \times 10^{18}$ cm$^{-2}$. This excludes the possibility that relevant HI masses at the periphery of galaxies are invisible at 21-cm in emission. The outermost interstellar gas in a disk galaxy is more directly affected by external processes and in this paper we estimate the intensity of the extragalactic background at energies close to 0.1 keV by comparing our theoretical results with HI emission/absorption studies. We take into account the possibility that some energy produced in the inner regions affects the energy balance in outer regions. We find that in the absence of any other local heat source QSO dominated background models are still compatible with the spin temperature limits derived for the two best documented HI emission/absorption studies in outer regions.Comment: 24 pages, 8 figures ARCETRI-PR-93-2

The Fermi Gamma-ray Burst Monitor: Results from the first two years

In the first two years since the launch of the Fermi Observatory, the Gamma-ray Burst Monitor (GBM) has detected over 500 Gamma-Ray Bursts (GRBs), of which 18 were confidently detected by the Large Area Telescope (LAT) above 100 MeV. Besides GRBs, GBM has triggered on other transient sources, such as Soft Gamma Repeaters (SGRs), Terrestrial Gamma-ray Flashes (TGFs) and solar flares. Here we present the science highlights of the GBM observations.Comment: 4 pages, 1 figure, Proceedings of the 8th Workshop on Science with the New Generation of High Energy Gamma-ray Experiments (SciNeGHE 2010), Nuovo Cimento C, in pres