W. R. Gibbs

The Pentaquark in K+ -d total cross section data

An analysis of K{sup +}-d total cross section data is undertaken to explore possible effects of the recently observed resonance in the S=+1 hadronic system with mass around 1.55 GeV. It is found that a structure corresponding to the resonance is visible in the data. The width consistent with the observed deviation from background is found to be 0.9{+-}0.3 MeV and the mass is 1.559{+-}0.003 GeV/c{sup 2} for spin parity (1/2){sup +} and 1.547{+-}0.002 GeV/c{sup 2} for (1/2){sup -}. The errors are one standard deviation and statistical only.

Pentaquark in K + ‐ d total cross section data

An analysis of K{sup +}-d total cross section data is undertaken to explore possible effects of the recently observed resonance in the S=+1 hadronic system with mass around 1.55 GeV. It is found that a structure corresponding to the resonance is visible in the data. The width consistent with the observed deviation from background is found to be 0.9{+-}0.3 MeV and the mass is 1.559{+-}0.003 GeV/c{sup 2} for spin parity (1/2){sup +} and 1.547{+-}0.002 GeV/c{sup 2} for (1/2){sup -}. The errors are one standard deviation and statistical only.

A parallel/recursive algorithm

An algorithm is discussed for converting a class of recursive processes to a parallel system. It is argued that this algorithm can be superior to certain methods currently found in the literature for an important subset of problems. The cases of homogeneous and non-homogeneous two term recursions are treated. The basic cost factor of the algorithm over non-parallel operations is 2 if only the final values of the sequence is needed and 4 if all elements are required. In practice, these factors can be reduced considerably. Applications to three problems (finding the eigenvalues of a tri-diagonal matrix, the solution of a radial wave equation and the solution of a tri-diagonal matrix) are discussed.

Partial-wave analysis of K+-nucleon scattering

We have performed a partial-wave analysis of K{sup +}-nucleon scattering in the momentum range from 0 to 1.5 GeV/c addressing the uncertainties of the results and comparing them with several previous analyses. It is found that the treatment of the reaction threshold behavior is particularly important. We find a T=0 scattering length which is not consistent with zero, as has been claimed by other analyses. The T=0 phase shifts for l>0 are consistent with a pure spin-orbit potential. Some indications for the production of a T=0 pentaquark with spin-parity-D5/2+ are discussed.

Pion charge exchange on deuterium

We investigate quantum corrections to a classical intranuclear cascade simulation of pion single charge exchange on the deuteron. In order to separate various effects, the orders of scattering need to be distinguished and, to that end, we develop signals for each order of scattering corresponding to quasifree conditions. Quantum corrections are evaluated for double scattering and are found to be large. Global agreement with the data is good.

Double charge exchange on medium mass nuclei

We studied the double-charge-exchange reaction on 93Nb and 56Fe targets. The energy dependence of forward transition was calculated based on an optical model with the nuclear structure described in the pseudo-SU(4) model.