FERMION HELICITY FLIP IN WEAK GRAVITATIONAL-FIELDS

The helicity flip of a spin-1/2 Dirac particle interacting gravitationally with a scalar field is analyzed in the context of linearized quantum gravity. It is shown that massive fermions may have their helicity flipped by gravity, in opposition to massless fermions which preserve their helicity.

SOME CONSEQUENCES IN WEAK PROCESSES OF 3-GENERATION MIXING IN THE LEPTONIC SECTOR

We investigate the sensitivity of some weak processes to a Cabibbo-Kobayashi-Maskawa in the leptonic sector. Values for mixing angles and masses compatible with several experimental accelerator data were found. We discuss in this context neutrino oscillations and cosmological and astrophysical consequences as well.

Weak decay of uniformly accelerated protons and related processes

We investigate the weak interaction emission of spin-1/2 fermions from accelerated currents. As particular applications, we analyze the decay of uniformly accelerated protons and neutrons, and the neutrino-antineutrino emission from uniformly accelerated electrons. The possible relevance of our results to astrophysics is also discussed.

Magnetic behavior of poly(3-methylthiophene): Metamagnetism and room-temperature weak ferromagnetism

A weak ferromagnetic phase is shown in pressed pellets of partially doped poly(3-methylthiophene) (P3MT) in the whole range from 1.8 to 300 K in magnetic measurements. Thermoremanence data have been used to estimate the suppression of this phase to be around 815 K. We also show that instead of the classical antiferromagnetism for the first-order interaction that gives weak ferromagnetism as a second-order effect, metamagnetic behavior is observed. X-band electron spin resonance (ESR) measurements and magnetization measurements allowed us to estimate that 8.1% of the total number of spins contributes to the weak ferromagnetism at room temperature. The doping level obtained from the ESR data is in good agreement with that estimated from electron dispersive spectroscopy measurements.

Structure and weak hydrogen bonds in liquid acetaldehyde

Monte Carlo simulations have been performed to investigate the structure and hydrogen bonds formation in liquid acetaldehyde. An all atom model for the acetaldehyde have been optimized in the present work. Theoretical values obtained for heat of vaporisation and density of the liquid are in good agreement with experimental data. Graphics of radial distribution function indicate a well structured liquid compared to other similar dipolar organic liquids. Molecular mechanics minimization in gas phase leads to a trimer of very stable structure. The geometry of this complex is in very good agreement with the rdf. The shortest site-site correlation is between oxygen and the carbonyl hydrogen, suggesting that this correlation play a important role in the liquid structure and properties. The O⋯H average distance and the C-H⋯O angle obtained are characteristic of weak hydrogen bonds.

Preliminary Overview of the Economies of Latin America and the Caribbean 2000

Includes bibliography

Preliminary Overview of the Economies of Latin America and the Caribbean 1999

Includes bibliography

Preliminary Overview of the Economies of Latin America and the Caribbean 2001

Includes bibliography

Preliminary Overview of the Economies of Latin America and the Caribbean 2002

Includes bibliography

Preliminary Overview of the Economies of Latin America and the Caribbean 2003

Includes bibliography

Preliminary Overview of the Economies of Latin America and the Caribbean 2004

Includes bibliography

Preliminary Overview of the Economies of Latin America and the Caribbean 2005

Includes bibliography

Preliminary Overview of the Economies of Latin America and the Caribbean 2006

Includes bibliography

Preliminary Overview of the Economies of Latin America and the Caribbean 2007

Includes bibliography

Preliminary Overview of the Economies of Latin America and the Caribbean 2008

Includes bibliography