5,441 research outputs found
Using Transit Timing Observations to Search for Trojans of Transiting Extrasolar Planets
Theoretical studies predict that Trojans are likely a frequent byproduct of
planet formation and evolution. We examine the sensitivity of transit timing
observations for detecting Trojan companions to transiting extrasolar planets.
We demonstrate that this method offers the potential to detect terrestrial-mass
Trojans using existing ground-based observatories. We compare the transit
timing variation (TTV) method with other techniques for detecting extrasolar
Trojans and outline the future prospects for this method.Comment: submitted to ApJL, 12 pages, 2 figure
Techniques for achieving magnetic cleanliness on deep-space missions
Techniques for obtaining magnetic cleanliness on deep space missions to allow interplanetary magnetic field mappin
Metastable Cosmic Strings in Realistic Models
We investigate the stability of the electroweak Z-string at high
temperatures. Our results show that while finite temperature corrections can
improve the stability of the Z-string, their effect is not strong enough to
stabilize the Z-string in the standard electroweak model. Consequently, the
Z-string will be unstable even under the conditions present during the
electroweak phase transition. We then consider phenomenologically viable models
based on the gauge group and show
that metastable strings exist and are stable to small perturbations for a large
region of the parameter space for these models. We also show that these strings
are superconducting with bosonic charge carriers. The string superconductivity
may be able to stabilize segments and loops against dynamical contraction.
Possible implications of these strings for cosmology are discussed.Comment: 24 pages, 2 figures (available on request); HUTP-92/A032,
Fermilab-Pub-92/228-
Non-Equilibrium Production of Photons via \pi^0\to 2\gamma in DCC's
We study production of photons via the non-equilibrium relaxation of a
Disoriented Chiral Condensate with the chiral order parameter having a large
initial amplitude along the \pi^0 direction. Assuming the validity of the low
energy coupling of the neutral pion to photons via the U_A(1) anomalous vertex,
we find that for large initial amplitudes along the \pi^0 direction, photon
production is enhanced by parametric amplification. These processes are
non-perturbative with a large contribution during the non-equilibrium stages of
the evolution and result in a distinct distribution of the produced photons and
a polarization asymmetry. For initial amplitudes of the \pi^0 component of the
order parameter between 200-400 MeV, corresponding to energy densities between
1-12 GeV/fm^3 we find a peak in the photon distribution at energies between
\approx 300 -600 MeV. We also find polarization asymmetries typically between
5-10%. We discuss the potential experimental impact of these results as well as
the problems associated with its detection.Comment: 36 pages, 14 figures, uses revte
- …