Richard A. Arndt

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(Received: February 1, 2008) A new result for the πN Σ term from a George Washington University/TRIUMF group analysis of πN data is presented. The value Σ=79±7 MeV was obtained, compared to the canonical value 64±8 MeV found by Koch. The difference is explained simply by the PSI pionic hydrogen value for aπ−p, the latest results for the πNN coupling(More)
A new result for the πN sigma term from an updated πN partial–wave and dispersion relation analysis of the Virginia Polytechnic Institute (now George Washington University) group is discussed. Using a method similar to that of Gasser, Leutwyler, Locher, and Sainio, we obtain Σ =90±8 MeV (preliminary), in disagreement with the canonical result 64±8 MeV, but(More)
We reexamine Chew’s method for extracting the πNN coupling constant from np differential cross section measurements. Values for this coupling are extracted below 350 MeV, in the potential model region, and up to 1 GeV. The analyses to 1 GeV have utilized 55 data sets. We compare these results to those obtained via χ mapping techniques. We find that these(More)
We present the results of an energy-dependent and set of single-energy partial-wave analyses of single-pion photoproduction data. These analyses extend from threshold to 2 GeV in the laboratory photon energy, and update our previous analyses to 1.8 GeV. Photo-decay amplitudes are extracted for the baryon resonances within this energy range. We consider two(More)
We have updated our multipole analyses to incorporate new data from the low-energy and delta resonance regions. We note a slight decrease in our estimate of the delta photo-decay amplitudes. This agrees with results found in Compton scattering. Our values are also in good agreement with a previous RPI determination. We have reexamined our determinations of(More)
containing the Born terms, with phenomenological pieces (α) maintaining the correct threshold behavior and Watson’s theorem. The πN T-matrix (TπN ) connects each multipole to structure found in the elastic πN scattering analysis. Additional structure is parametrized through the Born terms (which contain vector-meson contributions), and the phenomenological(More)
We present the results of energy-dependent and single-energy partial-wave analyses of πN elastic scattering data with laboratory kinetic energies below 2.1 GeV. Resonance structures have been extracted using Breit-Wigner fits, speed plots, and a complex plane mapping of the associated poles and zeroes. This is the first set of resonance parameters from a(More)