3,616 research outputs found
Fermion masses in a model for spontaneous parity breaking
In this paper we discuss a left-right symmetric model for elementary
particles and their connection with the mass spectrum of elementary fermions.
The model is based on the group . New
mirror fermions and a minimal set of Higgs particles that breaks the symmetry
down to are proposed. The model can accommodate a consistent
pattern for charged and neutral fermion masses as well as neutrino
oscillations. An important consequence of the model is that the connection
between the left and right sectors can be done by the neutral vector gauge
bosons Z and a new heavy Z'.Comment: 7 pages, 3 figures. Accepted in Eur. Phys. J.
Universal Behaviour of the Superfluid Fraction and Tc of He-3 in 99.5% Open Aerogel
We have investigated the superfluid transition of He-3 in a 99.5% porosity
silica aerogel. This very dilute sample shows behaviour intermediary between
bulk He-3 and He-3 confined to the denser aerogels previously studied. We
present data on both the superfluid transition temperature and the superfluid
density and compare our results with previous measurements. Finally, we show
that the suppression of the superfluid transition temperature and suppression
of the superfluid density of He-3 in aerogel follow a universal relation for a
range of aerogel samples.Comment: 4 pages, 5 figures; 1 new figure, minor change
Spin induced multipole moments for the gravitational wave amplitude from binary inspirals to 2.5 Post-Newtonian order
Using the NRGR effective field theory formalism we calculate the remaining
source multipole moments necessary to obtain the spin contributions to the
gravitational wave amplitude to 2.5 Post-Newtonian (PN) order. We also
reproduce the tail contribution to the waveform linear in spin at 2.5PN arising
from the nonlinear interaction between the current quadrupole and the mass
monopole.Comment: 17 pages, 4 figures. v2 Minor changes, to appear in JCA
Optimized minigaps for negative differential resistance creation in strongly delta-doped (1D) superlattices
The "atomic saw method" uses the passage of dislocations in two-dimensional
(2D) quantum-well superlattices to create periodic slipping layers and
one-dimensional (1D) quantum wire superlattices. The effects of this space
structuring of the samples on the allowed energies are analysed in the case of
GaAs d-doped superlattices. If they are sufficiently large, the various
minigaps appearing in the 1D band structure could be responsible for the
presence of negative differential resistance (NDR) with high critical current
in these systems. The purpose is to determine the evolution of the minigaps in
terms of the sample parameters and to obtain the means to determine both the 2D
and 1D structural characteristics where NDR could appear.Comment: see erratum 10.1006/spmi.1998.070
Optical bistability in subwavelength apertures containing nonlinear media
We develop a self-consistent method to study the optical response of metallic
gratings with nonlinear media embedded within their subwavelength slits. An
optical Kerr nonlinearity is considered. Due to the large E-fields associated
with the excitation of the transmission resonances appearing in this type of
structures, moderate incoming fluxes result in drastic changes in the
transmission spectra. Importantly, optical bistability is obtained for certain
ranges of both flux and wavelength.Comment: 4 pages, 4 figure
Study and characterization by magnetophonon resonance of the energy structuring in GaAs/AlAs quantum-wire superlattices
We present the characterization of the band structure of GaAs/AlAs
quantum-wire 1D superlattices performed by magnetophonon resonance with pulsed
magnetic fields up to 35 T. The samples, generated by the "atomic saw method"
from original quantum-well 2D superlattices, underwent substantial
modifications of their energy bands built up on the X-states of the bulk. We
have calculated the band structure by a finite element method and we have
studied the various miniband structures built up of the masses m_t and m_l of
GaAs and AlAs at the point X. From an experimental point of view, the main
result is that in the 2D case we observe only resonances when the magnetic
field B is applied along the growth axis whereas in the 1D case we obtain
resonances in all magnetic field configurations. The analysis of the maxima (or
minima for B // E) in the resistivity rho_xy as a function of B allows us to
account, qualitatively and semi-quantitatively, for the band structure
theoretically expected
On the transmission of light through a single rectangular hole
In this Letter we show that a single rectangular hole exhibits transmission
resonances that appear near the cutoff wavelength of the hole waveguide. For
light polarized with the electric field pointing along the short axis, it is
shown that the normalized-to-area transmittance at resonance is proportional to
the ratio between the long and short sides, and to the dielectric constant
inside the hole. Importantly, this resonant transmission process is accompanied
by a huge enhancement of the electric field at both entrance and exit
interfaces of the hole. These findings open the possibility of using
rectangular holes for spectroscopic purposes or for exploring non-linear
effects.Comment: Submitted to PRL on Feb. 9th, 200
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