21,311 research outputs found

    Charge assignments in multiple-U(1) gauge theories

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    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

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    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

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    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

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    Kiwi B nuclear rocket acoustics - sound pressure distribution, energy conversion, and power distributio

    Statistical Geometry in Quantum Mechanics

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    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

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    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

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    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

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    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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