75,986 research outputs found

    The RHMC Algorithm for 2 Flavours of Dynamical Staggered Fermions

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    We describe an implementation of the Rational Hybrid Monte Carlo (RHMC) algorithm for dynamical computations with two flavours of staggered quarks. We discuss several variants of the method, the performance and possible sources of error for each of them, and we compare the performance and results to the inexact R algorithm.Comment: Lattice2003(machine) 3 pages, 1 figure. Added referenc

    On the Holomorphic Structure of a Low Energy Supersymmetric Wilson Effective Action

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    The Wilson (exact) renormalization group equations are used to determine the evolution of a general low energy N=1 supersymmetric action containing a U(1) gauge vector multiplet and a neutral chiral multiplet. The effective theory evolves towards satisfying a fixed relation where the K\"ahler potential and effective gauge coupling are obtained from a N=2 supersymmetric holomorphic prepotential.Comment: 10 pages, LaTe

    The Accountability and Independence of the Auditors-General of Australia: A Comparison of their Enabling Legislation

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    This paper compares the enabling legislation of the nine auditors-general of Australia from perspectives of public-sector accountability and auditor independence. Following on from the Joint Committee of Public Accounts (JCPA) 1989 and 1996 reports, and in particular English and Guthrie (2000), this study finds general similarities in the enabling legislation for all auditors-general, and striking similarities between the legislation of the commonwealth and Victoria. The policy implications of this study's findings are that for all auditors-general provisions in their enabling legislation could be further strengthened

    Finding flows in the one-way measurement model

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    The one-way measurement model is a framework for universal quantum computation, in which algorithms are partially described by a graph G of entanglement relations on a collection of qubits. A sufficient condition for an algorithm to perform a unitary embedding between two Hilbert spaces is for the graph G, together with input/output vertices I, O \subset V(G), to have a flow in the sense introduced by Danos and Kashefi [quant-ph/0506062]. For the special case of |I| = |O|, using a graph-theoretic characterization, I show that such flows are unique when they exist. This leads to an efficient algorithm for finding flows, by a reduction to solved problems in graph theory.Comment: 8 pages, 3 figures: somewhat condensed and updated version, to appear in PR

    IRAS 18357-0604 – an analogue of the galactic yellow hypergiant IRC +10420?

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    Context. Yellow hypergiants represent a short-lived evolutionary episode experienced by massive stars as they transit to and from a red supergiant phase. As such, their properties provide a critical test of stellar evolutionary theory, while recent observations unexpectedly suggest that a subset may explode as Type II supernovae.Aims. The galactic yellow hypergiant IRC +10420 is a cornerstone system for understanding this phase since it is the strongest post-RSG candidate known, has demonstrated real-time evolution across the Hertzsprung-Russell diagram and been subject to extensive mass loss. In this paper we report on the discovery of a twin of IRC +10420 - IRAS 18357-0604.Methods. Optical and near-IR spectroscopy are used to investigate the physical properties of IRAS 18357-0604 and also provide an estimate of its systemic velocity, while near- to mid-IR photometry probes the nature of its circumstellar environment.Results. These observations reveal pronounced spectral similarities between IRAS 18357-0604 and IRC +10420, suggesting comparable temperatures and wind geometries. IR photometric data reveals a similarly dusty circumstellar environment, although historical mass loss appears to have been heavier in IRC +10420. The systemic velocity implies a distance compatible with the red supergiant-dominated complex at the base of the Scutum Crux arm; the resultant luminosity determination is consistent with a physical association but suggests a lower initial mass than inferred for IRC +10420 (≲20 M⊙ versus ~40 M⊙). Evolutionary predictions for the physical properties of supernova progenitors derived from ~18–20 M⊙ stars – or ~12–15 M⊙ stars that have experienced enhanced mass loss as red supergiants – compare favourably with those of IRAS 18357-0604, which in turn appears to be similar to the the progenitor of SN2011dh; it may therefore provide an important insight into the nature of the apparently H-depleted yellow hypergiant progenitors of some Type IIb SNe
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