740 research outputs found
SPIN - Progress and Prospects
I review the progress in fundamental spin physics over the past several years
and the prospects for the future. The progress is striking and the prospects
are excellent.Comment: A Talk Presented at SPIN2000, October 30, 2000; 21 pages, 13 figures,
using aiproc.sty, BoxedEPS macros; email correspondence to [email protected]
Nonequilibrium quantum fluctuations of a dispersive medium: Spontaneous emission, photon statistics, entropy generation, and stochastic motion
We study the implications of quantum fluctuations of a dispersive medium,
under steady rotation, either in or out of thermal equilibrium with its
environment. A rotating object exhibits a quantum instability by dissipating
its mechanical motion via spontaneous emission of photons, as well as internal
heat generation. Universal relations are derived for the radiated energy and
angular momentum as trace formulas involving the object's scattering matrix. We
also compute the quantum noise by deriving the full statistics of the radiated
photons out of thermal and/or dynamic equilibrium. The (entanglement) entropy
generation is quantified, and the total entropy is shown to be always
increasing. Furthermore, we derive a Fokker-Planck equation governing the
stochastic angular motion resulting from the fluctuating back-reaction
frictional torque. As a result, we find a quantum limit on the uncertainty of
the object's angular velocity in steady rotation. Finally, we show in some
detail that a rotating object drags nearby objects, making them spin parallel
to its axis of rotation. A scalar toy model is introduced in the first part to
simplify the technicalities and ease the conceptual complexities; a detailed
discussion of quantum electrodynamics is presented in the second part
Deep Inelastic Scattering with Application to Nuclear Targets: Lectures at the 1985 Los Alamos School on Relativistic Dynamics and Quark Nuclear Physics
This paper is essentially a verbatim reconstruction of lectures that I gave
at the Los Alamos School on Relativistic Dynamics and Quark Nuclear Physics in
1985. They were published in the school proceedings, but the book is not widely
available. The Los Alamos School took place at the height of the first wave of
interest in the quark substructure of nuclei, stimulated by the 1983 discovery
of the EMC Effect. Interest in this subject has been increasing for years and
the prospect of a dedicated Electron Ion Collider within the decade guarantees
even greater attention to quarks and gluons in nuclei among both theorists and
experimentalists.
Recently, to my surprise, I learned that copies of my old lectures have been
circulating and been found useful by the relatively few people who know about
them. The are, of course, dated: experiments have far outstripped what was
available 37 years ago and theory has progressed too. However, the rest frame
derivation of the parton model, the derivation and discussion of the
convolution formalism for nucleons, nucleon correlations, and other, virtual,
constituents of nuclei, and sections on scaling violation and the operator
product expansion have aged pretty well and seem to still be useful.
With the help and encouragement of Richard Milner, I have recreated the LaTeX
files necessary to post the 1985 Lectures on the arXiv, making them available
to the nuclear and particle physics community. Apart from correcting some
typographical errors, I have made no attempt to edit, improve, or update these
lectures. I hope readers will nevertheless find them useful.Comment: Reconstruction of Lectures at the 1985 Los Alamos School on
Relativistic Dynamics and Quark Nuclear Physic
Spectroscopic Probe of the van der Waals Interaction between Polar Molecules and a Curved Surface
We study the shift of rotational levels of a diatomic polar molecule due to
its van der Waals (vdW) interaction with a gently curved dielectric surface at
temperature , and submicron separations. The molecule is assumed to be in
its electronic and vibrational ground state, and the rotational degrees are
described by a rigid rotor model. We show that under these conditions
retardation effects and surface dispersion can be neglected. The level shifts
are found to be independent of , and given by the quantum state averaged
classical electrostatic interaction of the dipole with its image on the
surface. We use a derivative expansion for the static Green's function to
express the shifts in terms of surface curvature. We argue that the curvature
induced line splitting is experimentally observable, and not obscured by
natural line widths and thermal broadening.Comment: 8 pages, 2 figures, version accepted for publication in Phys. Rev.
Metals Production Requirements for Rapid Photovoltaics Deployment
If global photovoltaics (PV) deployment grows rapidly, the required input
materials need to be supplied at an increasing rate. In this paper, we quantify
the effect of PV deployment levels on the scale of metals production. For
example, we find that if cadmium telluride {copper indium gallium diselenide}
PV accounts for more than 3% {10%} of electricity generation by 2030, the
required growth rates for the production of indium and tellurium would exceed
historically-observed production growth rates for a large set of metals. In
contrast, even if crystalline silicon PV supplies all electricity in 2030, the
required silicon production growth rate would fall within the historical range.
More generally, this paper highlights possible constraints to the rate of
scaling up metals production for some PV technologies, and outlines an approach
to assessing projected metals growth requirements against an ensemble of past
growth rates from across the metals production sector. The framework developed
in this paper may be useful for evaluating the scalability of a wide range of
materials and devices, to inform technology development in the laboratory, as
well as public and private research investment
Electromagnetic Casimir Forces of Parabolic Cylinder and Knife-Edge Geometries
An exact calculation of electromagnetic scattering from a perfectly
conducting parabolic cylinder is employed to compute Casimir forces in several
configurations. These include interactions between a parabolic cylinder and a
plane, two parabolic cylinders, and a parabolic cylinder and an ordinary
cylinder. To elucidate the effect of boundaries, special attention is focused
on the "knife-edge" limit in which the parabolic cylinder becomes a half-plane.
Geometrical effects are illustrated by considering arbitrary rotations of a
parabolic cylinder around its focal axis, and arbitrary translations
perpendicular to this axis. A quite different geometrical arrangement is
explored for the case of an ordinary cylinder placed in the interior of a
parabolic cylinder. All of these results extend simply to nonzero temperatures.Comment: 17 pages, 10 figures, uses RevTeX
Implications of the Babinet Principle for Casimir Interactions
We formulate the Babinet Principle (BP) as a relation between the scattering
amplitudes for electromagnetic waves, and combine it with multiple scattering
techniques to derive new properties of Casimir forces. We show that the Casimir
force exerted by a planar conductor or dielectric on a self- complementary
perforated planar mirror is approximately half that on a uniform mirror
independent of the distance between them. The BP suggests that Casimir edge
effects are anomalously small, supporting results obtained earlier in special
cases. Finally, we illustrate how the BP can be used to estimate Casimir forces
between perforated planar mirrors
Ordinary and Extraordinary Hadrons
Resonances and enhancements in meson-meson scattering can be divided into two
classes distinguished by their behavior as the number of colors N_c in QCD
becomes large: The first are ordinary mesons that become stable as N_c goes to
infinity. This class includes textbook q-bar q mesons as well as glueballs and
hybrids. The second class, extraordinary mesons, are enhancements that
disappear as N_c goes to infinity; they subside into the hadronic continuum.
This class includes indistinct and controversial objects that have been
classified as q-bar q-bar q q mesons or meson-meson molecules. Pelaez's study
of the N_c dependence of unitarized chiral dynamics illustrates both classes:
the p-wave pi-pi and K-pi resonances, the rho(770) and K*(892), behave as
ordinary mesons; the s-wave pi-pi and K-pi enhancements, the sigma(600) and
kappa(800), behave like extraordinary mesons. Ordinary mesons resemble Feshbach
resonances while extraordinary mesons look more like effects due to potentials
in meson-meson scattering channels. I build and explore toy models along these
lines. Finally I discuss some related dynamical issues affecting the
interpretation of extraordinary mesons.Comment: 18 pages, 10 figures, talk presented at the 2006 Yukawa International
Seminar: New Frontiers in QCD, Kyoto University, November 2006. This talk is
dedicated to the memory of R. H. Dalit
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