William Kaufmann
Department of Physics and Astronomy


Research Interests
I am pursuing research in the interaction of hadrons (e.g. pions, kaon, or antiprotons) with atomic nuclei and with nucleons.  Over the years, I have been interested in the double charge exchange (DCX) reaction in which a positively charged pion transfers two units of charge to a pair of protons within a nucleus -- turning them into neutrons. The DCX process requires the participation of two nucleons, and it is very sensitive to the correlations between the positions of nucleons .  Isospin is an excellent symmetry of the strong interactions. By analyzing the world's experimental data on elastic and charge-exchange scattering of pions on protons, we (W. R. Gibbs, L. Ai, and W. Kaufmann) have found hints of possible isospin breaking beyond that expected from Coulomb and hadronic mass differences. In other work G. Hite and I have studied the  subthreshold amplitudes in pi pi systems and pion-nucleon systems with particular interest in testing chiral models.

Selected References
energy dependence of pion double charge exchange, Nuseirat et al. Phys. Rev. C 58, 2292 (1998)  dcx  (242Kb)
isospin breaking in the pi N system,W. B. Kaufmann and W. R. Gibbs, Annals of Physics  314 (1992)  formalism (432Kb)
isospin breaking in the low-energy pi N system, W. R. Gibbs, Li Ai, and W. B. Kaufmann, Phys. Rev. Lett. 74, 3740 (1995)  break (148Kb)
low energy pion nucleon scattering, W. R. Gibbs, Li Ai, and W. B. Kaufmann, Phys. Rev. C 57, 784 (1998) breakp (237Kb)
pi pi scattering amplitudes in the subthreshold region, G. E. Hite and W. B. Kaufmann, Phys. Rev. C 57, 931 (1998) pipi (1448Kb)
tests of current algebra and PCAC in the subthreshold region, W. B. Kaufmann and G. E. Hite, Phys. Rev. 60, 055204 (1999) piN (175Kb)
fundamental quantities from doubly subtracted forward dispersion relations, W. R. Gibbs and W. B. Kaufmann, pi N Newsletter 16, 286-288 (2002) dr
consistency of a large pi-N sigma term, M. G. Olsson and W. B. Kaufmann, pi N Newsletter 16, 382-384 (2002) sig
A fuller set of references may be found in  Spires

To return to the Department of Physics and Astronomy home page.

To contact me: William Kaufmann