Polarization parameter for nucleon-nucleon elastic scattering at 11.8 GeV/c

Abstract

Data are presented on the polarization parameter in $\mathrm{pp}$ and $\mathrm{pn}$ elastic scattering at 11.8 GeV/c for four-momentum transfers $-t=0.15\mathrm{} \mathrm{to} 0.9$ ${\mathrm{GeV}}^2$. In contrast to lower energies where the $\mathrm{pn}$ polarization is positive, it is slightly negative at 11.8 GeV/c; averaging the data from $-t=0.18\mathrm{} \mathrm{to} 0.5$ ${\mathrm{GeV}}^2$ we find $P\left(\mathrm{pn}\right)=(-0.9\mathrm{}\pm 0.5)\%$, to be compared with $P\left(\mathrm{pp}\right)=(5.6\mathrm{}\pm 0.8)\%$. These data, combined with our previous data at lower energies, show that the $I=0\mathrm{}$ single-flip exchange amplitude has an anomalously rapid energy dependence.