Amplitude Analysis of Charge-Exchange and Strangeness-Exchange Processes in Pseudoscalar-Meson-Baryon Scattering Using the Dual Absorptive Model

An amplitude analysis of charge-exchange and strangeness-exchange reactions in pseudoscalar-meson-baryon scattering is presented for the momentum interval ∼ 4 to ∼ 16 GeV/c. The imaginary parts of the $s$-channel helicity-nonflip and helicity-flip amplitudes are assumed to have "$J_0$" and "$J_1$" structures, respectively, as specified by the dual absorptive model of Harari. This model has been successful previously in explaining the main features of elastic scattering data. The present analysis applies this model to inelastic scattering reactions and determines empirically the real part of the $s$-channel nonflip amplitude from the data. The resulting amplitudes reproduce well the existing differential cross section and polarization data for charge-exchange and strangeness-exchange reactions. The $\rho$ and $A_2$ amplitudes in $\mathrm{KN}$ charge exchange are found to be in approximate agreement with strong exchange degeneracy. In contrast, the $K^{*}$ and $K^{**}$ amplitudes in $\Sigma$ and $\Lambda$ reactions are not strongly exchange-degenerate, even though equal forward differential cross sections are observed for the line-reversed pairs of reactions $\pi N\to \mathrm{KY}$ and $\overline{K}N\to \pi Y$.