13,279 research outputs found
Covariant approach to equilibration in effective field theories
The equilibration of two coupled reservoirs is studied using a Green function
approach which is suitable for future development with the closed time path
method. The problem is solved in two parameterizations, in order to demonstrate
the non-trivial issues of parameterization in both the intermediate steps and
the interpretation of physical quantities. We use a covariant approach to find
self-consistent solutions for the statistical distributions as functions of
time. We show that by formally introducing covariant connections, one can
rescale a slowly varying non-equilibrium theory so that it appears to be an
equilibrium one, for the purposes of calculation. We emphasize the importance
of properly tracking variable redefinitions in order to correctly interpret
physical quantities.Comment: 11 pages, Late
SNAP-2 RELIABILITY PROGRAM
The basic concept of the SNAP 2 reliability program is discussed. The basis for the reliability requirements for SNAP 2 is presented, and the fundamental methods by which these requirements can be accomplished are described. The reliability objectives for the system, a description of basic failure characteristics, and design considerations for reliability margins and component selection are presented, together with test plans for establishing reliability margins and for demonstrating system reliability. (auth
Magnetic Field Rotations in the Solar Wind at Kinetic Scales
The solar wind magnetic field contains rotations at a broad range of scales,
which have been extensively studied in the MHD range. Here we present an
extension of this analysis to the range between ion and electron kinetic
scales. The distribution of rotation angles was found to be approximately
log-normal, shifting to smaller angles at smaller scales almost self-similarly,
but with small, statistically significant changes of shape. The fraction of
energy in fluctuations with angles larger than was found to drop
approximately exponentially with , with e-folding angle at
ion scales and at electron scales, showing that large angles
() do not contain a significant amount of energy at kinetic
scales. Implications for kinetic turbulence theory and the dissipation of solar
wind turbulence are discussed
The static potential in QED with non-minimal coupling
Here we study the effect of the non-minimal coupling j^{\mu}\eps
\partial^{\nu} A^{\alpha} on the static potential in multiflavor QED.
Both cases of four and two components fermions are studied separately at
leading order in the expansion. Although a non-local Chern-Simons term
appears, in the four components case the photon is still massless leading to a
confining logarithmic potential similar to the classical one. In the two
components case, as expected, the parity breaking fermion mass term generates a
traditional Chern-Simons term which makes the photon massive and we have a
screening potential which vanishes at large inter-charge distance. The extra
non-minimal couplings have no important influence on the static potential at
large inter-charge distances. However, interesting effects show up at finite
distances. In particular, for strong enough non-minimal coupling we may have a
new massive pole in the photon propagator while in the opposite limit there may
be no poles at all in the irreducible case. We also found that, in general, the
non-minimal couplings lead to a finite range {\bf repulsive} force between
charges of opposite signs.Comment: 19 pages and 7 figure
Design and test of a 100 ampere-hour nickel cadmium battery module
A feasibility study was conducted on the design and construction of a flight-worthy replaceable battery module consisting of four 100 A.H. nickel-cadmium rechargeable cells for large manned space vehicles. The module is planned to weigh less than 43 pounds and be fully maintainable in a zero-g environment by one man without use of special tools. An active environmental control system was designed for the temperature control of the module
Duality and Non-linear Response for Quantum Hall Systems
We derive the implications of particle-vortex duality for the electromagnetic
response of Quantum Hall systems beyond the linear-response regime. This
provides a first theoretical explanation of the remarkable duality which has
been observed in the nonlinear regime for the electromagnetic response of
Quantum Hall systems.Comment: 7 pages, 1 figure, typeset in LaTe
The high partial wave phenomenon of spin changing atomic transitions
The collisional transition between two highly excited atomic states with different spin is investigated theoretically. Taking helium-like n1S â n3P as an example, it is found that the transition is driven in the highly ion-ized Fe ion purely by exchange, and the cross section becomes increasingly dominated by partial waves of high orbital angular momentum as the scattering energy increases. Whereas for the near-neutral Li ion the transition is dominated by channel coupling in low partial waves. Analytical bench-marks and numerical methods are developed for the accurate calculation of the exchange integral at high angular momentum. It is shown how the partial wave and energy dependence of the collision strength for high n spin changing transitions in the highly ionized ion is related to the overlap of the extended atomic orbitals.</p
Scaling Solutions to 6D Gauged Chiral Supergravity
We construct explicitly time-dependent exact solutions to the field equations
of 6D gauged chiral supergravity, compactified to 4D in the presence of up to
two 3-branes situated within the extra dimensions. The solutions we find are
scaling solutions, and are plausibly attractors which represent the late-time
evolution of a broad class of initial conditions. By matching their near-brane
boundary conditions to physical brane properties we argue that these solutions
(together with the known maximally-symmetric solutions and a new class of
non-Lorentz-invariant static solutions, which we also present here) describe
the bulk geometry between a pair of 3-branes with non-trivial on-brane
equations of state.Comment: Contribution to the New Journal of Physics focus issue on Dark
Energy; 28 page
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