A Rosetta Stone Relating Conventions In Photo-Meson Partial Wave Analyses

A new generation of complete experiments in pseudoscalar meson photo-production is being pursued at several laboratories. While new data are emerging, there is some confusion regarding definitions of asymmetries and the conventions used in partial wave analyses (PWA). We present expressions for constructing asymmetries as coordinate-system independent ratios of cross sections, along with the names used for these ratios by different PWA groups. (This update reflects a recent change in the definition of an asymmetry as used by one group.)Comment: v2: This update reflects a recent change in the definition of an asymmetry as used by one PWA group -see Table 1. v1: 4 pages. Contribution to the proceedings of the 8th International Workshop on the Physics of Excited Nucleons (NSTAR2011), Newport News, VA, USA, May 17-20, 201

Spin observables for pion photoproduction on the deuteron in the Δ\Delta(1232)-resonance region

Spin observables for the three charge states of the pion for the pion photoproduction reaction on the deuteron, $\gamma d\to\pi NN$, with polarized photon beam and/or oriented deuteron target are predicted. For the beam-target double-spin asymmetries, it is found that only the longitudinal asymmetries $T_{20}^{\ell}$ and $T_{2\pm 2}^{\ell}$ do not vanish, whereas all the circular and the other longitudinal asymmetries do vanish. The sensitivity of spin observables to the model deuteron wave function is investigated. It has been found that only $T_{21}$ and $T_{22}$ are sensitive to the model deuteron wave function, in particular in the case of $\pi^0$-production above the $\Delta$-region, and that other asymmetries are not.Comment: 16 pages, 8 figures, accepted for publication in J. Phys. G: Nucl. Part. Phy

Measurements of polarized photo-pion production on longitudinally polarized HD and Implications for Convergence of the GDH Integral

We report new measurements of inclusive pion production from frozen-spin HD for polarized photon beams covering the Delta(1232) resonance. These provide data simultaneously on both H and D with nearly complete angular distributions of the spin-difference cross sections entering the Gerasimov-Drell-Hearn (GDH) sum rule. Recent results from Mainz and Bonn exceed the GDH prediction for the proton by 22 microbarns, suggesting as yet unmeasured high-energy components. Our pi0 data reveal a different angular dependence than assumed in Mainz analyses and integrate to a value that is 18 microbarns lower, suggesting a more rapid convergence. Our results for deuterium are somewhat lower than published data, considerably more precise and generally lower than available calculations.Comment: 4 pages, 4 figures. Submitted for publication in Physical Review Letter

Description of twelve cases of nephrogenic fibrosing dermopathy and review of the literature

ABSTRACT Objectives: To review the clinical and laboratory features of twelve cases of nephrogenic fibrosing dermopathy (NFD) studied at our institution and of 70 previously described cases in the literature. Methods: Clinical evaluation and laboratory studies of twelve patients with NFD associated with chronic hemodialysis or peritoneal dialysis for end-stage renal disease and a review of 23 previous publications describing 70 patients with this disease. Results: Eleven patients undergoing chronic hemodialysis and one patient undergoing chronic peritoneal dialysis for end-stage renal failure developed a severe and progressive cutaneous fibrotic process with woody induration of legs, thighs, hands and forearms, and severe loss of motion and flexion contractures in multiple joints. Several patients displayed systemic involvement including fibrosis of muscles, myocardium and lungs and marked elevations of the erythrocyte sedimentation rate and/or C reactive protein. Three patients died within two years of onset of symptoms. A review of previously published reports of this disorder confirmed the presence of systemic involvement and a poor prognosis with a high rate of mortality. Conclusions: The analysis of twelve cases and a review of 70 previously described cases indicate that NFD is a severe and usually progressive systemic fibrotic disease affecting the dermis, subcutaneous fascia and striated muscles. It also appears that the disease can cause fibrosis of lungs, myocardium and other organs

Pseudoscalar meson photoproduction: from known to undiscovered resonances

The role of dynamics in spin observables for pseudoscalar meson photoproduction is investigated using a density matrix approach in a multipole truncated framework. Extraction of novel rules for $\gamma p \rightarrow \pi^+ n,~ K^+ \Lambda$ and $\eta p$ reactions based on resonance dominance, and on other broad and reasonable dynamical assumptions, are discussed. Observables that are particularly sensitive to missing nucleonic resonances predicted by quark-based approaches, are singled out.Comment: 22 pages, latex, 3 figure