4,644 research outputs found
Hadron mass corrections in semi-inclusive deep-inelastic scattering
The spin-dependent cross sections for semi-inclusive lepton-nucleon
scattering are derived in the framework of collinear factorization, including
the effects of masses of the target and produced hadron at finite momentum
transfer squared Q^2. At leading order the cross sections factorize into
products of parton distribution and fragmentation functions evaluated in terms
of new, mass-dependent scaling variables. The size of the hadron mass
corrections is estimated at kinematics relevant for future semi-inclusive
deep-inelastic scattering experiments.Comment: 28 pages, 12 figures, published versio
Physics Potential of Very Intense Conventional Neutrino Beams
The physics potential of high intensity conventional beams is explored. We
consider a low energy super beam which could be produced by a proposed new
accelerator at CERN, the Super Proton Linac. Water Cherenkov and liquid oil
scintillator detectors are studied as possible candidates for a neutrino
oscillation experiment which could improve our current knowledge of the
atmospheric parameters and measure or severely constrain the parameter
connecting the atmospheric and solar realms. It is also shown that a very large
water detector could eventually observe leptonic CP violation. The reach of
such an experiment to the neutrino mixing parameters would lie in-between the
next generation of neutrino experiments (MINOS, OPERA, etc) and a future
neutrino factory.Comment: Talk given at the Venice Conference on Neutrino Telescopes, Venice,
March, 200
Physics Potential of the SPL Super Beam
Performances of a neutrino beam generated by the CERN SPL proton driver are
computed considering a 440 kton water Cerenkov detector at 130 km from the
target. sensitivity down to and a
sensitivity comparable to a Neutrino Factory, for ,
are within the reach of such a project.Comment: Invited talk at the Nufact02 Workshop, Imperial College of Science,
Technology and Medicine, London, July 200
Searching for hexagonal analogues of the half-metallic half-Heusler XYZ compounds
The XYZ half-Heusler crystal structure can conveniently be described as a
tetrahedral zinc blende YZ structure which is stuffed by a slightly ionic X
species. This description is well suited to understand the electronic structure
of semiconducting 8-electron compounds such as LiAlSi (formulated
Li[AlSi]) or semiconducting 18-electron compounds such as TiCoSb
(formulated Ti[CoSb]). The basis for this is that [AlSi]
(with the same electron count as Si) and [CoSb] (the same electron
count as GaSb), are both structurally and electronically, zinc-blende
semiconductors. The electronic structure of half-metallic ferromagnets in this
structure type can then be described as semiconductors with stuffing magnetic
ions which have a local moment: For example, 22 electron MnNiSb can be written
Mn[NiSb]. The tendency in the 18 electron compound for a
semiconducting gap -- believed to arise from strong covalency -- is carried
over in MnNiSb to a tendency for a gap in one spin direction. Here we similarly
propose the systematic examination of 18-electron hexagonal compounds for
semiconducting gaps; these would be the "stuffed wurtzite" analogues of the
"stuffed zinc blende" half-Heusler compounds. These semiconductors could then
serve as the basis for possibly new families of half-metallic compounds,
attained through appropriate replacement of non-magnetic ions by magnetic ones.
These semiconductors and semimetals with tunable charge carrier concentrations
could also be interesting in the context of magnetoresistive and thermoelectric
materials.Comment: 11 pages, 6 figures, of which 4 are colou
Brain-specific tropomyosins TMBr-1 and TMBr-3 have distinct patterns of expression during development and in adult brain
In this study we report on the developmental and regional expression of two brain-specific isoforms of tropomyosin, TMBr-1 and TMBr-3, that are generated from the rat alpha-tropomyosin gene via the use of alternative promoters and alternative RNA splicing. Western blot analysis using an exon-specific peptide polyclonal antibody revealed that the two isoforms are differentially expressed in development with TMBr-3 appearing in the embryonic brain at 16 days of gestation, followed by the expression of TMBr-1 at 20 days after birth. TMBr-3 was detected in all brain regions examined, whereas TMBr-1 was detected predominantly in brain areas that derived from the prosencephalon. Immunocytochemical studies on mixed primary cultures made from rat embryonic midbrain indicate that expression of the brain-specific epitope is restricted to neurons. The developmental pattern and neuronal localization of these forms of tropomyosin suggest that these isoforms have a specialized role in the development and plasticity of the nervous system
Possible Effects of Quantum Mechanics Violation Induced by Certain Quantum Gravity on Neutrino Oscillations
In this work we tried extensively to apply the EHNS postulation about the
quantum mechanics violation effects induced by the quantum gravity of black
holes to neutrino oscillations. The possibilities for observing such effects in
the neutrino experiments (in progress and/or accessible in the near future)
were discussed. Of them, an interesting one was outlined specially.Comment: 18 pages, 0 figure, (1 REVTeX file
- …