Systematic study ofπ±p,K±p,pp, andp¯pforward elastic scattering from3 to 6 GeVc

Abstract

Measurements of ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}p$, ${K}^{\ifmmode\pm\else\textpm\fi{}}p$, $\mathrm{pp}$, and $\overline{p}p$ elastic scattering are presented for incident momenta of 3, 3.65, 5, and $6 \frac{\mathrm{GeV}}{c}$ and momentum transfers typically $0.03 \mathrm{to} 1.8 \mathrm{Ge}{\mathrm{V}}^{2}$. The angle and momentum of the scattered particle were measured with the Argonne Effective Mass Spectrometer for 300 000 events, yielding 930 cross-section values with an uncertainty in absolute normalization of \ifmmode\pm\else\textpm\fi{}4%. Only the ${K}^{+}$ and proton data show any significant change in slope of the forward diffraction peak with incident momentum. The particle-antiparticle crossover positions are consistent with no energy dependence, average values being 0.14 \ifmmode\pm\else\textpm\fi{} 0.03, 0.190 \ifmmode\pm\else\textpm\fi{} 0.006, and 0.162 \ifmmode\pm\else\textpm\fi{} 0.004 Ge${\mathrm{V}}^{2}$ for $\ensuremath{\pi}$' s, $K$' s, and protons, respectively; these errors reflect both statistics and the \ifmmode\pm\else\textpm\fi{}1.5% uncertainty in particle-antiparticle relative normalization. Differences between particle and antiparticle cross sections isolate interference terms between amplitudes of opposite $C$ parity in the $t$ channel; these differences indicate that the imaginary part of the odd-$C$ nonflip-helicity amplitude has a ${J}_{0}(r{(\ensuremath{-}t)}^{\frac{1}{2}})$ structure for $\ensuremath{-}t<0.8$ Ge${\mathrm{V}}^{2}$, as predicted by strong absorption models. The cross-section differences for ${K}^{\ifmmode\pm\else\textpm\fi{}}$ and proton-antiproton are in qualitative agreement with the predictions of $\ensuremath{\omega}$ universality, the agreement improving with increasing energy. The corresponding quark-model predictions relating the ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$ and ${K}^{\ifmmode\pm\else\textpm\fi{}}$ differences failed by more than a factor of 2. We have combined our ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$ cross sections with other data to better determine the $\ensuremath{\pi}N$ amplitudes in a model-independent way; results of this analysis are presented.