Worldgraph Approach to Yang-Mills Amplitudes from N=2 Spinning Particle

By coupling the N=2 spinning particle to background vector fields, we construct Yang-Mills amplitudes for trees and one loop. The vertex operators are derived through coupling the BRST charge; therefore background gauge invariance is manifest, and the Yang-Mills ghosts are automatically included in loop calculations by worldline ghosts. Inspired by string calculations, we extend the usual worldline approach to incorporate more "generalized" 1D manifolds. This new approach should be useful for constructing higher-point and higher-loop amplitudes.Comment: 21 pages, 4 figures; v2: 22 pages, 5 figures, major changes in section V, typos correcte

Cracks in the Sandbox: Mobilizing Existing International Legal Tools to Fill Gaps in Sand Mining Regulations

Sand sustains the foundations of modern economies, but almost nothing exists in the way of global sand regulation and governance. Despite the documented risks posed by rampant, unregulated extraction, a global governance regime is unlikely to emerge any time soon. This Comment argues that possible governance solutions will need to come from what we currently have in the legal toolbox. In other words, existing frameworks, principles, and lessons from case law must be drawn upon and refitted to tackle some of the most salient issues caused by sand mining. This Comment aims to illustrate that even a highly fractured legal landscape can still offer invaluable guidance moving forward. To that end, this Comment also explores the first possible steps toward a global governance framework. Specifically, countries should take advantage of lowhanging fruit—easy opportunities to integrate sand into existing frameworks and concepts—in order to patch critical regulatory gaps and establish a foundation for future cooperative efforts

Modeling and Analysis of Power Processing Systems (MAPPS), initial phase 2

The overall objective of the program is to provide the engineering tools to reduce the analysis, design, and development effort, and thus the cost, in achieving the required performances for switching regulators and dc-dc converter systems. The program was both tutorial and application oriented. Various analytical methods were described in detail and supplemented with examples, and those with standardization appeals were reduced into computer-based subprograms. Major program efforts included those concerning small and large signal control-dependent performance analysis and simulation, control circuit design, power circuit design and optimization, system configuration study, and system performance simulation. Techniques including discrete time domain, conventional frequency domain, Lagrange multiplier, nonlinear programming, and control design synthesis were employed in these efforts. To enhance interactive conversation between the modeling and analysis subprograms and the user, a working prototype of the Data Management Program was also developed to facilitate expansion as future subprogram capabilities increase

Extreme case of Faraday effect: magnetic splitting of ultrashort laser pulses in plasmas

The Faraday effect, caused by a magnetic-field-induced change in the optical properties, takes place in a vast variety of systems from a single atomic layer of graphenes to huge galaxies. Currently, it plays a pivot role in many applications such as the manipulation of light and the probing of magnetic fields and material's properties. Basically, this effect causes a polarization rotation of light during its propagation along the magnetic field in a medium. Here, we report an extreme case of the Faraday effect where a linearly polarized ultrashort laser pulse splits in time into two circularly polarized pulses of opposite handedness during its propagation in a highly magnetized plasma. This offers a new degree of freedom for manipulating ultrashort and ultrahigh power laser pulses. Together with technologies of ultra-strong magnetic fields, it may pave the way for novel optical devices, such as magnetized plasma polarizers. In addition, it may offer a powerful means to measure strong magnetic fields in laser-produced plasmas.Comment: 18 pages, 5 figure