ΔσL(pp) and jet physics

We show that there is a positive contribution to Δ${\sigma }_L$(pp;s) =${\sigma }_{\mathrm{tot}\left(\mathit{p}\mathrm{}\right(+\left)\mathrm{}\mathit{p}\mathrm{}\right(+);\mathit{s})}$ -${\sigma }_{\mathrm{tot}\left(\mathit{p}\mathrm{}\right(+\left)\mathrm{}\mathit{p}\right(\mathrm{-});\mathit{s})}$ (where the ± refer to proton helicities) associated with the pointlike scattering of fundamental constituents. The magnitude and energy dependence of this hard-scattering component are related to the small-x behavior of spin-weighted parton densities. Simple arguments imply that this positive contribution would, at very large s, be larger in absolute value than the negative contribution to Δ${\sigma }_L$ predicted from the exchange of the $A_1$ Reggeon. Measurements of Δ${\sigma }_L$ in the energy range √s =18–30 GeV should help clarify theoretical ideas associated with the observation of ‘‘minijets’’ and could aid in the prediction of event structure at future high-energy colliders.