20 research outputs found
Coherent Ï0 photoproduction on the deuteron up to 4 GeV
The differential cross section for 2H(Îł,d)Ï0 has been measured at deuteron center-of-mass angles of 90° and 136°. This work reports the first data for this reaction above a photon energy of 1 GeV, and permits a test of the apparent constituent counting rule and reduced nuclear amplitude behavior as observed in elastic ed scattering. Measurements were performed up to a photon energy of 4.0 GeV, and are in good agreement with previous lower energy measurements. Overall, the data are inconsistent with both constituent-counting rule and reduced nuclear amplitude predictions
Measurements of Deuteron Photodisintegration up to 4.0 GeV
The first measurements of the differential cross section for the d(γ,p)n reaction up to 4.0 GeV were performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at Thomas Jefferson Laboratory. We report the cross sections at the proton center-of-mass angles of 36°, 52°, 69°, and 89°. These results are in reasonable agreement with previous measurements at lower energy. The 89° and 69° data show constituent-counting-rule behavior up to 4.0 GeV photon energy. The 52° and 36° data disagree with the counting-rule behavior. The quantum chromodynamics (QCD) model of nuclear reactions involving reduced amplitudes disagrees with the present data.U.S. Department of Energy, National Science Foundatio
The criminal profiling illusion:what's behind the smoke and mirrors?
There is a belief that criminal profilers can predict a criminal's characteristics from crime scene evidence. In this article, the authors argue that this belief may be an illusion and explain how people may have been misled into believing that criminal profiling (CP) works despite no sound theoretical grounding and no strong empirical support for this possibility. Potentially responsible for this illusory belief is the information that people acquire about CP, which is heavily influenced by anecdotes, repetition of the message that profiling works, the expert profiler label, and a disproportionate emphasis on correct predictions. Also potentially responsible are aspects of information processing such as reasoning errors, creating meaning out of ambiguous information, imitating good ideas, and inferring fact from fiction. The authors conclude that CP should not be used as an investigative tool because it lacks scientific support
Revealing the structure of light pseudoscalar mesons at the electronâion collider
International audienceThe questions of how the bulk of the Universeâs visible mass emerges and how it is manifest in the existence and properties of hadrons are profound, and probe the heart of strongly interacting matter. Paradoxically, the lightest pseudoscalar mesons appear to be key to a further understanding of the emergent mass and structure mechanisms. These mesons, namely, the pion and kaon, are the NambuâGoldstone boson modes of quantum chromodynamics (QCD). Unravelling their partonic structure and the interplay between emergent and Higgs-boson mass mechanisms is a common goal of three interdependent approachesâcontinuum QCD phenomenology, lattice-regularised QCD, and the global analysis of parton distributionsâlinked to experimental measurements of hadron structure. Experimentally, the anticipated electronâion collider will enable a revolution in our ability to study pion and kaon structures, accessed by scattering from the âmeson cloudâ of the proton through the Sullivan process. With the goal of enabling a suite of measurements that can address these questions, we examine key reactions that identify the critical detector-system requirements needed to map tagged pion and kaon cross-sections over a wide range of kinematics. The excellent prospects for extracting pion structural, functional, and form-factor data are outlined, and similar prospects for kaon structures are discussed in the context of a worldwide programme. The successful completion of the programme outlined herein will deliver deep, far-reaching insights into the emergence of pions and kaons, their properties, and their role as QCDâs Goldstone boson modes