Atomic Model of Susy Hubbard Operators

We apply the recently proposed susy Hubbard operators to an atomic model. In the limiting case of free spins, we derive exact results for the entropy which are compared with a mean field + gaussian corrections description. We show how these results can be extended to the case of charge fluctuations and calculate exact results for the partition function, free energy and heat capacity of an atomic model for some simple examples. Wavefunctions of possible states are listed. We compare the accuracy of large N expansions of the susy spin operators with those obtained using `Schwinger bosons' and `Abrikosov pseudo-fermions'. For the atomic model, we compare results of slave boson, slave fermion, and susy Hubbard operator approximations in the physically interesting but uncontrolled limiting case of N->2. For a mixed representation of spins we estimate the accuracy of large N expansions of the atomic model. In the single box limit, we find that the lowest energy saddle-point solution reduces to simply either slave bosons or slave fermions, while for higher boxes this is not the case. The highest energy saddle-point solution has the interesting feature that it admits a small region of a mixed representation, which bears a superficial resemblance to that seen experimentally close to an antiferromagnetic quantum critical point.Comment: 17 pages + 7 pages Appendices, 14 figures. Substantial revision

Support of the Third Solar Wind conference

The program of invited talks at the Third Solar Wind Conference is provided, with a table of contents of the proceedings

Magnetic latitude effects in the solar wind

The Weber-Davis model of the solar wind is generalized to include the effects of latitude. The principal assumptions of high electrical conductivity, rotational symmetry, the polytropic relation between pressure and density, and a flow-alined field in a system rotating with the sun, are retained. An approximate solution to the resulting equations for spherical boundary conditions at the base of the corona indicates a small component of latitudinal flow toward the solar poles at large distances from the sun as result of latitudinal magnetic forces

On the relation between Euclidean and Lorentzian 2D quantum gravity

Starting from 2D Euclidean quantum gravity, we show that one recovers 2D Lorentzian quantum gravity by removing all baby universes. Using a peeling procedure to decompose the discrete, triangulated geometries along a one-dimensional path, we explicitly associate with each Euclidean space-time a (generalized) Lorentzian space-time. This motivates a map between the parameter spaces of the two theories, under which their propagators get identified. In two dimensions, Lorentzian quantum gravity can therefore be viewed as a ``renormalized'' version of Euclidean quantum gravity.Comment: 12 pages, 2 figure

Design of experiments for non-manufacturing processes : benefits, challenges and some examples

Design of Experiments (DoE) is a powerful technique for process optimization that has been widely deployed in almost all types of manufacturing processes and is used extensively in product and process design and development. There have not been as many efforts to apply powerful quality improvement techniques such as DoE to improve non-manufacturing processes. Factor levels often involve changing the way people work and so have to be handled carefully. It is even more important to get everyone working as a team. This paper explores the benefits and challenges in the application of DoE in non-manufacturing contexts. The viewpoints regarding the benefits and challenges of DoE in the non-manufacturing arena are gathered from a number of leading academics and practitioners in the field. The paper also makes an attempt to demystify the fact that DoE is not just applicable to manufacturing industries; rather it is equally applicable to non-manufacturing processes within manufacturing companies. The last part of the paper illustrates some case examples showing the power of the technique in non-manufacturing environments

Apollo particles and fields subsatellite magnetometer experiment

The results of the Apollo 15 subsatellite magnetometer experiment are reported. The magnetometer is described including the operation, and specifications. Orbit plots presented are altitude versus time, selenographic longitude versus latitude, and the ecliptic projection of the earth-moon system. The lunar magnetic field, solar wind interaction with the moon, the transfer function of the moon, and the plasma sheet interaction with the moon are discussed

Heavy-fermion metals with hybridization nodes: Unconventional Fermi liquids and competing phases

Microscopic models for heavy-fermion materials often assume a local, i.e., momentum-independent, hybridization between the conduction band and the local-moment f electrons. Motivated by recent experiments, we consider situations where this neglect of momentum dependence is inappropriate, namely when the hybridization function has nodes in momentum space. We explore the thermodynamic and optical properties of the highly anisotropic heavy Fermi liquid, resulting from Kondo screening in a higher angular-momentum channel. The dichotomy in momentum space has interesting consequences: While e.g. the low-temperature specific heat is dominated by heavy quasiparticles, the electrical conductivity at intermediate temperatures is carried by unhybridized light electrons. We then discuss aspects of the competition between Kondo effect and ordering phenomena induced by inter-moment exchange: We propose that the strong momentum-space anisotropy plays a vital role in selecting competing phases. Explicit results are obtained for the interplay of unconventional hybridization with unconventional, magnetically mediated, superconductivity, utilizing variants of large-N mean-field theory. We make connections to recent experiments on CeCoIn5 and other heavy-fermion materials.Comment: 16 pages, 8 figs, (v2) remark on Wiedemann-Franz added, small changes, final version as publishe

Local Moments in an Interacting Environment

We discuss how local moment physics is modified by the presence of interactions in the conduction sea. Interactions in the conduction sea are shown to open up new symmetry channels for the exchange of spin with the localized moment. We illustrate this conclusion in the strong-coupling limit by carrying out a Schrieffer Wolff transformation for a local moment in an interacting electron sea, and show that these corrections become very severe in the approach to a Mott transition. As an example, we show how the Zhang Rice reduction of a two-band model is modified by these new effects.Comment: Latex file with two postscript figures. Revised version, with more fully detailed calculation

Vacuum Decay in Theories with Symmetry Breaking by Radiative Corrections

The standard bounce formalism for calculating the decay rate of a metastable vacuum cannot be applied to theories in which the symmetry breaking is due to radiative corrections, because in such theories the tree-level action has no bounce solutions. In this paper I derive a modified formalism to deal with such cases. As in the usual case, the bubble nucleation rate may be written in the form $A e^{-B}$. To leading approximation, $B$ is the bounce action obtained by replacing the tree-level potential by the leading one-loop approximation to the effective potential, in agreement with the generally adopted {\it ad hoc} remedy. The next correction to $B$ (which is proportional to an inverse power of a small coupling) is given in terms of the next-to-leading term in the effective potential and the leading correction to the two-derivative term in the effective action. The corrections beyond these (which may be included in the prefactor) do not have simple expressions in terms of the effective potential and the other functions in the effective action. In particular, the scalar-loop terms which give an imaginary part to the effective potential do not explicitly appear; the corresponding effects are included in a functional determinant which gives a manifestly real result for the nucleation rate.Comment: 39 pages, CU-TP-57