1,018 research outputs found
Electron to selectron pair conversion in a SUSY bubble
In the standard model, energy release in dense stars is severely restricted
by the Pauli exclusion principle. However, if, in regions of space of high
fermion degeneracy, there is a phase transition to a state of exact
supersymmetry (SUSY), fermion to sfermion pair conversion followed by radiative
transitions to the Bose ground state could lead to a highly collimated gamma
ray burst. We calculate the cross section for electron to selectron pair
conversion in a SUSY bubble and construct a monte carlo for the resulting
sfermion amplification by stimulated emission.Comment: 13 pages, 4 figures, published version with "with jet production by
Bose enhancement" added to titl
Automated supervised classification of variable stars I. Methodology
The fast classification of new variable stars is an important step in making
them available for further research. Selection of science targets from large
databases is much more efficient if they have been classified first. Defining
the classes in terms of physical parameters is also important to get an
unbiased statistical view on the variability mechanisms and the borders of
instability strips. Our goal is twofold: provide an overview of the stellar
variability classes that are presently known, in terms of some relevant stellar
parameters; use the class descriptions obtained as the basis for an automated
`supervised classification' of large databases. Such automated classification
will compare and assign new objects to a set of pre-defined variability
training classes. For every variability class, a literature search was
performed to find as many well-known member stars as possible, or a
considerable subset if too many were present. Next, we searched on-line and
private databases for their light curves in the visible band and performed
period analysis and harmonic fitting. The derived light curve parameters are
used to describe the classes and define the training classifiers. We compared
the performance of different classifiers in terms of percentage of correct
identification, of confusion among classes and of computation time. We describe
how well the classes can be separated using the proposed set of parameters and
how future improvements can be made, based on new large databases such as the
light curves to be assembled by the CoRoT and Kepler space missions.Comment: This paper has been accepted for publication in Astronomy and
Astrophysics (reference AA/2007/7638) Number of pages: 27 Number of figures:
1
Energy Conservation Constraints on Multiplicity Correlations in QCD Jets
We compute analytically the effects of energy conservation on the
self-similar structure of parton correlations in QCD jets. The calculations are
performed both in the constant and running coupling cases. It is shown that the
corrections are phenomenologically sizeable. On a theoretical ground, energy
conservation constraints preserve the scaling properties of correlations in QCD
jets beyond the leading log approximation.Comment: 11 pages, latex, 5 figures, .tar.gz version avaliable on
ftp://www.inln.unice.fr
Effect van ethyleen na voorbehandeling met zilverthiosulfaat bij verschillende cultivars Freesia
Selectron Studies at e-e- and e+e- Colliders
Selectrons may be studied in both e-e- and e+e- collisions at future linear
colliders. Relative to e+e-, the e-e- mode benefits from negligible backgrounds
and \beta threshold behavior for identical selectron pair production, but
suffers from luminosity degradation and increased initial state radiation and
beamstrahlung. We include all of these effects and compare the potential for
selectron mass measurements in the two modes. The virtues of the e-e- collider
far outweigh its disadvantages. In particular, the selectron mass may be
measured to 100 MeV with a total integrated luminosity of 1 fb^-1, while more
than 100 fb^-1 is required in e+e- collisions for similar precision.Comment: 16 pages, 11 figure
Minimal 3-3-1 model, lepton mixing and muonium-antimuonium conversion
The recent experimental results on neutrino oscillation and on
muonium-antimuonium conversion require extension of the minimal 3-3-1 model. We
review the constraints imposed to the model by those measurements and suggest a
pattern of leptonic mixing, with charged leptons in a non-diagonal basis, which
accounts for the neutrino physics and circumvents the tight muonium-antimuonium
bounds on the model. We also illustrate a scenario where this pattern could be
realized.Comment: 4 pages; abbreviated version, conclusions unchange
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