2,095,377 research outputs found
Majorana neutrino versus Dirac neutrino in through radiative corrections
Radiative corrections to from Majorana neutrinos are studied in the context of the
see-saw mechanism. Focusing on the effects of the fourth generation neutrinos,
we calculate W-pair form factors, the differential cross sections and the
forward-backward asymmetries for the polarized electrons at one-loop level. The
behaviour of the form factors at the threshold of Majorana particle pair
productions is found to differ from that of Dirac particle pair productions. In
the cross section for unpolarized electrons, the radiative corrections,
depending on the mass parameters of the see-saw mechanism, are found to be
at the energy range of the LEP200 and the next generation linear
colliders.Comment: 10 pages, Latex, 4 figures(no included, available on request
The Charge Form Factor of the Neutron at Low Momentum Transfer from the Reaction
We report new measurements of the neutron charge form factor at low momentum
transfer using quasielastic electrodisintegration of the deuteron.
Longitudinally polarized electrons at an energy of 850 MeV were scattered from
an isotopically pure, highly polarized deuterium gas target. The scattered
electrons and coincident neutrons were measured by the Bates Large Acceptance
Spectrometer Toroid (BLAST) detector. The neutron form factor ratio
was extracted from the beam-target vector asymmetry
at four-momentum transfers , 0.20, 0.29 and 0.42
(GeV/c).Comment: 5 pages, 3 figures, submitted to Phys. Rev. Let
Transmission Electron Study of Heteroepitaxial Growth in the BiSrCaCuO System
Films of BiSrCaCuO and BiSrCuO have been grown using Atomic-Layer-by-Layer Molecular Beam
Epitaxy (ALL-MBE) on lattice-matched substrates. These materials have been
combined with layers of closely-related metastable compounds like BiSrCaCuO (2278) and rare-earth-doped
compounds like BiSrDyCaCuO
(Dy:2212) to form heterostructures with unique superconducting properties,
including superconductor/insulator multilayers and tunnel junctions.
Transmission electron microscopy (TEM) has been used to study the morphology
and microstructure of these heterostructures. These TEM studies shed light on
the physical properties of the films, and give insight into the growth mode of
highly anisotropic solids like BiSrCaCuO.Comment: 17 pages, submitted to J. Materials Research. Email to
[email protected] if you want to receive copies of the figure
Possible existence of Ep-Lp and Ep-Eiso correlations for Short Gamma-Ray Bursts with a factor 5 to 100 dimmer than those for Long Gamma-Ray Bursts
We analyzed correlations among the rest frame spectral peak energy , the observed frame 64ms peak isotropic luminosity and the
isotropic energy for 13 Short Gamma Ray Burst (SGRB) candidates
having the measured redshift , sec and well
determined spectral parameters. A SGRB candidate is regarded as a misguided
SGRB if it is located in the 3- dispersion region from the
best-fit function of the -- correlation for Long GRBs
(LGRBs) while the others are regarded as secure SGRBs possibly from compact
star mergers. Using 8 secure SGRBs out of 13 SGRB candidates, we tested whether
-- and -- correlations exist for
SGRBs. We found that -- correlation for SGRBs() seems to exist with the correlation coefficeint and chance
probability . We found also that the -- correlation for SGRBs() is tighter than -- correlation since and . Both
correlations for SGRBs are dimmer than those of LGRBs for the same
by factors 100 (--) and 5(--). Applying the tighter -- correlation
for SGRBs to 71 bright BATSE SGRBs, we found that pseudo redshift ranges
from 0.097 to 2.258 with the mean of 1.05. The redshifts of SGRBs
apparently cluster at lower redshift than those of LGRBs (),
which supports the merger scenario of SGRBs.Comment: 8 pages, 6 figures, Accepted for publication in MNRA
Lattice effects in the LaSrCuO compounds
Systematic Raman studies on several cuprates (YBaCuO, YBaCuO or BiSrCaCuO) have shown that at optimal doping the compounds
are at the edge of lattice instability; once this level is exceeded, by means
of doping or applying external hydrostatic pressure, the changes in the
transition temperature are accompanied by spectral modifications. There are
strong indications that the reduction in T is correlated with a
separation into nanoscale phases, which involve the oxygen atoms of the
CuO planes. In this work, modifications with doping in the Raman
spectra of the LaSrCuO compound are presented,
which show that spin or charge ordering is coupled with lattice distortions in
the whole doping region.Comment: 6 pages, 6 figure
Kernel solutions of the Kostant operator on eight-dimensional quotient spaces
After introducing the generators and irreducible representations of the and Lie algebras in terms of the Schwinger's scillators,
the general kernel solutions of the Kostant operators on eight-dimensional
quotient spaces and are derived in terms of the diagonal
subalgebras and ,
respectively.Comment: 13 pages. Typos correcte
Theory Morphisms in Church's Type Theory with Quotation and Evaluation
is a version of Church's type theory with global
quotation and evaluation operators that is engineered to reason about the
interplay of syntax and semantics and to formalize syntax-based mathematical
algorithms. is a variant of that
admits undefined expressions, partial functions, and multiple base types of
individuals. It is better suited than as a logic for
building networks of theories connected by theory morphisms. This paper
presents the syntax and semantics of , defines a notion of
a theory morphism from one theory to another, and gives
two simple examples that illustrate the use of theory morphisms in .Comment: 17 page
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