Universal properties of elastic pp cross section from the ISR to the LHC

Abstract

We explore the phenomenology of the property that the ratio of bump to dip {\em positions} of the elastic differential $pp$ cross section is constant over the energy range from the ISR to the LHC. We review the old idea of geometric scaling at the ISR and argue that it also holds at the LHC. We discuss its consequences for the $\rho$ parameter and for the ratio of bump to dip cross section {\em values}.

Comments: 4 pages, 3 figures, 1 photo. Contribution to the 2025 QCD session of the 59th Rencontres de Moriond