Contact interactions and polarized beams at a Linear Collider

We discuss contact-interaction searches in the processes e^+e^-\to \mu^+\mu^-, b\bar{b} and c\bar{c} at an e^+e^- Linear Collider with c.m. energy \sqrt{s}=0.5 TeV and with longitudinally polarized beams. The measurement of polarized cross sections allows to study the individual helicity cross sections, and consequently to derive separate, model-independent, constraints on the four-fermion contact interaction couplings. We evaluate the reach on those parameters foreseeable in the case of both electron and positron polarization fixed at some reference values, and compare it with the situation where only electron polarization is available. The analysis is based on polarized integrated cross sections with optimal kinematical cuts that can improve the sensitivity to the relevant couplings. While electron polarization would by itself allow such an analysis, the additional positron polarization (with no loss of beam intensity) and optimization can have a crucial role in improving the sensitivity to the new interactions.Comment: 13 pages, LaTeX, including figure

Self-dual SU(2) invariant Einstein metrics and modular dependence of theta-functions

We simplify Hitchin's description of SU(2)-invariant self-dual Einstein metrics, making use of the tau-function of related four-pole Schlesinger system.Comment: A wrong sign in the formula for W_1 is corrected; we thank Owen Dearricott who pointed out this mistake in the original version of the pape

Parallelizing the QUDA Library for Multi-GPU Calculations in Lattice Quantum Chromodynamics

Graphics Processing Units (GPUs) are having a transformational effect on numerical lattice quantum chromodynamics (LQCD) calculations of importance in nuclear and particle physics. The QUDA library provides a package of mixed precision sparse matrix linear solvers for LQCD applications, supporting single GPUs based on NVIDIA's Compute Unified Device Architecture (CUDA). This library, interfaced to the QDP++/Chroma framework for LQCD calculations, is currently in production use on the "9g" cluster at the Jefferson Laboratory, enabling unprecedented price/performance for a range of problems in LQCD. Nevertheless, memory constraints on current GPU devices limit the problem sizes that can be tackled. In this contribution we describe the parallelization of the QUDA library onto multiple GPUs using MPI, including strategies for the overlapping of communication and computation. We report on both weak and strong scaling for up to 32 GPUs interconnected by InfiniBand, on which we sustain in excess of 4 Tflops.Comment: 11 pages, 7 figures, to appear in the Proceedings of Supercomputing 2010 (submitted April 12, 2010

Model-independent constraints on contact interactions from LEP2 data analysis

We derive model-independent constraints on four-fermion contact interaction-type dynamics from the published preliminary LEP2 experimental data on e^+e^- annihilation into \mu^+\mu^- and \tau^+\tau^- pairs, measured at different energies between 130 and 207 GeV. The basic observables are chosen to be the total cross section and the forward-backward asymmetry, and the analysis realistically takes into account data uncertainties and correlations among measurements at the various energies. The combination of data from different energy points plays an important role in the determination of regions allowed for the contact interaction coupling constants. In contrast to the more common one-parameter analyses, we only obtain constraints on pairs of parameters rather than limits on individual ones.Comment: 13 pages, LaTeX, including figures. v2: Included discussion of tau data, version to appear in EPJ

Active Instrument Cables with Buffer Amplification

ABSTRACT Title of Thesis: ACTIVE INSTRUMENT CABLES WITH BUFFER AMPLIFICATION Timothy A. Babich, Master of Science, 2011 Thesis Directed by: Professor Patrick O'Shea Department of Electrical and Computer Engineering "When connecting electronic instruments to power amplifiers with traditional passive instrument cables signal attenuations can occur due to several factors such as signal reflections and cable capacitance. This thesis examines the possibility of better preserving electronic instrument signals by using buffer amplification built into instrument cables. Active instrument cables were developed that are powered by an internal AA battery in a form factor similar to traditional passive cables. The goal was to achieve a design that was small and had substantial battery life such that the product would be marketable to musicians.

Attitudes and Perceptions of High School Mathematics Teachers Regarding Students\u27 Cognitive-Metacognitive Skills

The purpose of the study was to identify the attitudes and perceptions held by select teachers in a Midwest high school regarding teaching strategies related to students solving mathematics problems from a cognitive-metacognitive approach. The case study utilized a questionnaire regarding instructional practices and teacher beliefs and opinions as well as semi-structured interviews. Teachers commented on definitions and beliefs regarding thinking about thinking, thinking mathematically, and conceptual and procedural understanding. Furthermore, teachers discussed teaching strategies utilized to teach thinking about thinking in mathematics, effects of school-wide metacognitive training efforts, and usage of student reflection activities. The specificity and sophistication of responses related to perceptions held and strategies utilized seemed to increase with the years of experience teaching for participants