13,279 research outputs found

    Covariant approach to equilibration in effective field theories

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    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

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    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

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    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 α\alpha was found to drop approximately exponentially with α\alpha, with e-folding angle 9.8∘9.8^\circ at ion scales and 0.66∘0.66^\circ at electron scales, showing that large angles (α>30∘\alpha > 30^\circ) 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 QED3_3 with non-minimal coupling

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    Here we study the effect of the non-minimal coupling j^{\mu}\eps \partial^{\nu} A^{\alpha} on the static potential in multiflavor QED3_3. Both cases of four and two components fermions are studied separately at leading order in the 1/N1/N 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

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    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

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    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

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    The collisional transition between two highly excited atomic states with different spin is investigated theoretically. Taking helium-like n1S − 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

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    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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