21,490 research outputs found
Charge assignments in multiple-U(1) gauge theories
We discuss the choice of gauge field basis in multiple-U(1) gauge theories.
We find that there is a preferred basis, specified by the charge orthogonality
condition, in which the U(1) gauge fields do not mix under one-loop
renormalization group running.Comment: 7 pages, LaTe
Book Reviews
Polk: Due Process of Law under the Federal Constitution; Ivins and Mason: The Control of Public Utilities in the form of an annotation of the Public Service Commissions Law of the State of New York and covering all important American cases; Best: The Principles of the Law of Evidence, with elementary rules for conducting the examination of witnesses; Schouler: Ideals of the Republic; Correspondenc
Ultracold, radiative charge transfer in hybrid Yb ion - Rb atom traps
Ultracold hybrid ion-atom traps offer the possibility of microscopic
manipulation of quantum coherences in the gas using the ion as a probe.
However, inelastic processes, particularly charge transfer can be a significant
process of ion loss and has been measured experimentally for the Yb ion
immersed in a Rb vapour. We use first-principles quantum chemistry codes to
obtain the potential energy curves and dipole moments for the lowest-lying
energy states of this complex. Calculations for the radiative decay processes
cross sections and rate coefficients are presented for the total decay
processes. Comparing the semi-classical Langevin approximation with the quantum
approach, we find it provides a very good estimate of the background at higher
energies. The results demonstrate that radiative decay mechanisms are important
over the energy and temperature region considered. In fact, the Langevin
process of ion-atom collisions dominates cold ion-atom collisions. For spin
dependent processes \cite{kohl13} the anisotropic magnetic dipole-dipole
interaction and the second-order spin-orbit coupling can play important roles,
inducing couplingbetween the spin and the orbital motion. They measured the
spin-relaxing collision rate to be approximately 5 orders of magnitude higher
than the charge-exchange collision rate \cite{kohl13}. Regarding the measured
radiative charge transfer collision rate, we find that our calculation is in
very good agreement with experiment and with previous calculations.
Nonetheless, we find no broad resonances features that might underly a strong
isotope effect. In conclusion, we find, in agreement with previous theory that
the isotope anomaly observed in experiment remains an open question.Comment: 7 figures, 1 table accepted for publication in J. Phys. B: At. Mol.
Opt. Phys. arXiv admin note: text overlap with arXiv:1107.114
An acoustical study of the KIWI B nuclear rocket
Kiwi B nuclear rocket acoustics - sound pressure distribution, energy conversion, and power distributio
Statistical Geometry in Quantum Mechanics
A statistical model M is a family of probability distributions, characterised
by a set of continuous parameters known as the parameter space. This possesses
natural geometrical properties induced by the embedding of the family of
probability distributions into the Hilbert space H. By consideration of the
square-root density function we can regard M as a submanifold of the unit
sphere in H. Therefore, H embodies the `state space' of the probability
distributions, and the geometry of M can be described in terms of the embedding
of in H. The geometry in question is characterised by a natural Riemannian
metric (the Fisher-Rao metric), thus allowing us to formulate the principles of
classical statistical inference in a natural geometric setting. In particular,
we focus attention on the variance lower bounds for statistical estimation, and
establish generalisations of the classical Cramer-Rao and Bhattacharyya
inequalities. The statistical model M is then specialised to the case of a
submanifold of the state space of a quantum mechanical system. This is pursued
by introducing a compatible complex structure on the underlying real Hilbert
space, which allows the operations of ordinary quantum mechanics to be
reinterpreted in the language of real Hilbert space geometry. The application
of generalised variance bounds in the case of quantum statistical estimation
leads to a set of higher order corrections to the Heisenberg uncertainty
relations for canonically conjugate observables.Comment: 32 pages, LaTex file, Extended version to include quantum measurement
theor
Vacuum Alignment in Technicolor Theories-I. The Technifermion Sector
We have carried out numerical studies of vacuum alignment in technicolor
models of electroweak and flavor symmetry breaking. The goal is to understand
alignment's implications for strong and weak CP nonconservation in quark
interactions. In this first part, we restrict our attention to the
technifermion sector of simple models. We find several interesting phenomena,
including (1) the possibility that all observable phases in the technifermions'
unitary vacuum-alignment matrix are integer multiples of \pi/N' where N' \le N,
the number of technifermion doublets, and (2) the possibility of exceptionally
light pseudoGoldstone technipions.Comment: 19 pages, Latex with one postscript figur
Recent Legal Literature
Beale: The Law of Innkeepers and Hotels, including other Public Houses, Theatres, Sleeping Cars; Beale: The Law of Railroad Rate Regulation, with special reference to American Legislation; Moore: A Treatise on the Law of Carriers; Bernard: The First Year of Roman Law; Holland: The Elements of Jurisprudence; Wilcox: Foibles of the Bench; Wigmore (ed.): A Selection of Cases on Evidence for the Use of Students of Law; Fairlie: Local Government in Counties, Towns and Villages; Hirschl: Trial Tactics. A Treatment of the Methods of Conducting Litigatio
Book Reviews
Tucker: Contracts in Engineering; Osborn: Questioned Documents--A Study of Questioned Documents with an Outline of Methods by which the Facts may be Discovered and Shown; Scott (ed. and trans.): The Visigothic Code (Forum Judicum
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