Persistence of forward structure inπ−+p→π0+nup to 100 GeV/c: A possible new absorption phenomenon

In ${\pi }^{-}p\to {\pi }^{0}n$, the persistence of the dip at $t=0\mathrm{}$ in $\frac{d\sigma }{dt}$ up to $p_{\mathrm{lab}}=100\mathrm{}$ GeV/c and a lower ${\alpha }_{\mathrm{eff}}\mathrm{}(t=0\mathrm{})\mathrm{}$ above 20 GeV/c indicate an absorption effect in the nonflip amplitude due to peripherally produced nonelastic diffractive intermediate states whose total contribution, when summed with the triple-Regge technique, is $s^{\alpha }\ln \left(\ln s\right)$ for large $s$ and small $t$. An excellent description of small-$t$ data from 5 to 100 GeV/c is obtained.