46,084 research outputs found
Testing SUSY models of lepton flavor violation at a photon collider
The loop level lepton flavor violating signals are studied in a scenario of
low-energy, R-parity conserving, supersymmetric seesaw mechanism within the
context of a high energy photon collider. Lepton flavor violation is due to off
diagonal elements in the left s-lepton mass matrix induced by renormalization
group equations. The average slepton masses and the off
diagonal matrix elements are treated as model independent free
phenomenological parameters in order to discover regions in the parameter space
where the signal cross section may be observable. At the energies of the
option of the future high-energy linear collider the signal has
a potentially large standard model background, and therefore particular
attention is paid to the study of kinematical cuts in order to reduce the
latter at an acceptable level. We find, for the () channel,
non-negligible fractions of the parameter space () where the statistical significance ()
is .Comment: 26 pages, 12 figures, Revtex
Decay of distance autocorrelation and Lyapunov exponents
This work presents numerical evidences that for discrete dynamical systems
with one positive Lyapunov exponent the decay of the distance autocorrelation
is always related to the Lyapunov exponent. Distinct decay laws for the
distance autocorrelation are observed for different systems, namely exponential
decays for the quadratic map, logarithmic for the H\'enon map and power-law for
the conservative standard map. In all these cases the decay exponent is close
to the positive Lyapunov exponent. For hyperbolic conservative systems, the
power-law decay of the distance autocorrelation tends to be guided by the
smallest Lyapunov exponent.Comment: 7 pages, 8 figure
On the -Dirac Oscillator revisited
This Letter is based on the -Dirac equation, derived from the
-Poincar\'{e}-Hopf algebra. It is shown that the -Dirac
equation preserves parity while breaks charge conjugation and time reversal
symmetries. Introducing the Dirac oscillator prescription,
, in the -Dirac
equation, one obtains the -Dirac oscillator. Using a decomposition in
terms of spin angular functions, one achieves the deformed radial equations,
with the associated deformed energy eigenvalues and eigenfunctions. The
deformation parameter breaks the infinite degeneracy of the Dirac oscillator.
In the case where , one recovers the energy eigenvalues and
eigenfunctions of the Dirac oscillator.Comment: 5 pages, no figures, accepted for publication in Physics Letters
Baryon loading and the Weibel instability in gamma-ray bursts
The dynamics of two counter-streaming electron-positron-ion unmagnetized
plasma shells with zero net charge is analyzed in the context of magnetic field
generation in GRB internal shocks due to the Weibel instability. The effects of
large thermal motion of plasma particles, arbitrary mixture of plasma species
and space charge effects are taken into account. We show that, although thermal
effects slow down the instability, baryon loading leads to a non-negligible
growth rate even for large temperatures and different shell velocities, thus
guaranteeing the robustness and the occurrence of the Weibel instability for a
wide range of scenarios.Comment: 6 pages, 4 figures. Accepted for publication in MNRA
Search for Associations Containing Young stars (SACY): Chemical tagging IC 2391 & the Argus association
We explore the possible connection between the open cluster IC 2391 and the
unbound Argus association identified by the SACY survey. In addition to common
kinematics and ages between these two systems, here we explore their chemical
abundance patterns to confirm if the two substructures shared a common origin.
We carry out a homogenous high-resolution elemental abundance study of eight
confirmed members of IC 2391 as well as six members of the Argus association
using UVES spectra. We derive spectroscopic stellar parameters and abundances
for Fe, Na, Mg, Al, Si, Ca, Ti, Cr, Ni and Ba.
All stars in the open cluster and Argus association were found to share
similar abundances with the scatter well within the uncertainties, where [Fe/H]
= -0.04 +/-0.03 for cluster stars and [Fe/H] = -0.06 +/-0.05 for Argus stars.
Effects of over-ionisation/excitation were seen for stars cooler than roughly
5200K as previously noted in the literature. Also, enhanced Ba abundances of
around 0.6 dex were observed in both systems. The common ages, kinematics and
chemical abundances strongly support that the Argus association stars
originated from the open cluster IC 2391. Simple modeling of this system find
this dissolution to be consistent with two-body interactions.Comment: 17 pages, 7 figs, accepted for publication in MNRA
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