The Lorentz-Dirac and Landau-Lifshitz equations from the perspective of modern renormalization theory

This paper uses elementary techniques drawn from renormalization theory to derive the Lorentz-Dirac equation for the relativistic classical electron from the Maxwell-Lorentz equations for a classical charged particle coupled to the electromagnetic field. I show that the resulting effective theory, valid for electron motions that change over distances large compared to the classical electron radius, reduces naturally to the Landau-Lifshitz equation. No familiarity with renormalization or quantum field theory is assumed

Simulations and cosmological inference: A statistical model for power spectra means and covariances

We describe an approximate statistical model for the sample variance distribution of the non-linear matter power spectrum that can be calibrated from limited numbers of simulations. Our model retains the common assumption of a multivariate Normal distribution for the power spectrum band powers, but takes full account of the (parameter dependent) power spectrum covariance. The model is calibrated using an extension of the framework in Habib et al. (2007) to train Gaussian processes for the power spectrum mean and covariance given a set of simulation runs over a hypercube in parameter space. We demonstrate the performance of this machinery by estimating the parameters of a power-law model for the power spectrum. Within this framework, our calibrated sample variance distribution is robust to errors in the estimated covariance and shows rapid convergence of the posterior parameter constraints with the number of training simulations.Comment: 14 pages, 3 figures, matches final version published in PR

Cosmic Calibration: Constraints from the Matter Power Spectrum and the Cosmic Microwave Background

Several cosmological measurements have attained significant levels of maturity and accuracy over the last decade. Continuing this trend, future observations promise measurements of the statistics of the cosmic mass distribution at an accuracy level of one percent out to spatial scales with k~10 h/Mpc and even smaller, entering highly nonlinear regimes of gravitational instability. In order to interpret these observations and extract useful cosmological information from them, such as the equation of state of dark energy, very costly high precision, multi-physics simulations must be performed. We have recently implemented a new statistical framework with the aim of obtaining accurate parameter constraints from combining observations with a limited number of simulations. The key idea is the replacement of the full simulator by a fast emulator with controlled error bounds. In this paper, we provide a detailed description of the methodology and extend the framework to include joint analysis of cosmic microwave background and large scale structure measurements. Our framework is especially well-suited for upcoming large scale structure probes of dark energy such as baryon acoustic oscillations and, especially, weak lensing, where percent level accuracy on nonlinear scales is needed.Comment: 15 pages, 14 figure

Joint DOE-PNC research on the use of transparency in support of nuclear nonproliferation

PNC and LANL collaborated in research on the concept of transparency in nuclear nonproliferation. The research was based on the Action Sheet No. 21, which was signed in February 1996, ``The Joint Research on Transparency in Nuclear Nonproliferation`` under the ``Agreement between the Power Reactor and Nuclear Fuel Development Corporation of Japan (PNC) and the US Department of Energy (DOE) for Cooperation in Research and Development Concerning Nuclear Material Control and Accounting Measures for Safeguards and Nonproliferation``. The purpose of Action Sheet 21 is to provide a fundamental study on Transparency to clarify the means to improve worldwide acceptability for the nuclear energy from the nuclear nonproliferation point of view. This project consists of independent research and then joint discussion at workshops that address a series of topics and issues in transparency. The activities covered in Action Sheet 21 took place over a period of 18 months. Three workshops were held; the first and the third hosted by PNC in Tokyo, Japan and the second hosted by LANL in Los Alamos, New Mexico, US. The following is a summary of the three workshops. The first workshop addressed the policy environment of transparency. Each side presented its perspective on the following issues: (1) a definition of transparency, (2) reasons for transparency, (3) detailed goals of transparency and (4) obstacles to transparency. The topic of the second workshop was ``Development of Transparency Options.`` The activities accomplished were (1) identify type of facilities where transparency might be applied, (2) define criteria for applying transparency, and (3) delineate applicable transparency options. The goal of the third workshop, ``Technical Options for Transparency,`` was to (1) identify conceptual options for transparency system design; (2) identify instrumentation, measurement, data collection and data processing options; (3) identify data display options; and (4) identify technical options for reprocessing, enrichment, and MOX fuel fabrication facilities

Improved Nonrelativistic QCD for Heavy Quark Physics

We construct an improved version of nonrelativistic QCD for use in lattice simulations of heavy quark physics, with the goal of reducing systematic errors from all sources to below 10\%. We develop power counting rules to assess the importance of the various operators in the action and compute all leading order corrections required by relativity and finite lattice spacing. We discuss radiative corrections to tree level coupling constants, presenting a procedure that effectively resums the largest such corrections to all orders in perturbation theory. Finally, we comment on the size of nonperturbative contributions to the coupling constants.Comment: 40 pages, 2 figures (not included), in LaTe

Joint DOE-PNC research on the use of transparency in support of nuclear nonproliferation

PNC and LANL collaborated in research on the concept of transparency in nuclear nonproliferation. The research was based on the Action Sheet No. 21, which was signed in February 1996, ``The Joint Research on Transparency in Nuclear Nonproliferation`` under the ``Agreement between the Power Reactor and Nuclear Fuel Development Corporation of Japan (PNC) and the US Department of Energy (DOE) for Cooperation in Research and Development Concerning Nuclear Material Control and Accounting Measures for Safeguards and Nonproliferation``. The purpose of Action Sheet 21 is to provide a fundamental study on Transparency to clarify the means to improve worldwide acceptability for the nuclear energy from the nuclear nonproliferation point of view. This project consists of independent research and then joint discussion at workshops that address a series of topics and issues in transparency. The activities covered in Action Sheet 21 took place over a period of 18 months. Three workshops were held; the first and the third hosted by PNC in Tokyo, Japan and the second hosted by LANL in Los Alamos, New Mexico, US. The following is a summary of the three workshops. The first workshop addressed the policy environment of transparency. Each side presented its perspective on the following issues: (1) a definition of transparency, (2) reasons for transparency, (3) detailed goals of transparency and (4) obstacles to transparency. The topic of the second workshop was ``Development of Transparency Options.`` The activities accomplished were (1) identify type of facilities where transparency might be applied, (2) define criteria for applying transparency, and (3) delineate applicable transparency options. The goal of the third workshop, ``Technical Options for Transparency,`` was to (1) identify conceptual options for transparency system design; (2) identify instrumentation, measurement, data collection and data processing options; (3) identify data display options; and (4) identify technical options for reprocessing, enrichment, and MOX fuel fabrication facilities