title: Experimental confirmation that the proton is asymptotically a black disk.
abstract: Although experimentally accessible energies cannot probe "asymptopia", recent measurements of inelastic pp cross sections at the LHC at 7000 GeV and by Auger at 57,000 GeV allow us to conclude that (i) both σ(inel) and σ(tot), the inelastic and total cross sections for pp and pp interactions, saturate the Froissart bound of ln(2)s, (ii) when s→∞, the ratio σ(inel)/σ(tot) is experimentally determined to be 0.509 ± 0.021, consistent with the value 0.5 required by a black disk at infinite energies, and (iii) when s→∞, the forward scattering amplitude becomes purely imaginary, another requirement for the proton to become a totally absorbing black disk. Experimental verification of the hypotheses of analyticity and unitarity over the center of mass energy range 6 ≤ √s ≤ 57000 GeV are discussed. In QCD, the black disk is naturally made of gluons; our results suggest that the lowest-lying glueball mass is 2.97 ± 0.03 GeV.
authors.affiliation: Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Martin M
authors.initials: MM
authors.lastname: Block
authors.forename: Francis
authors.initials: F
authors.lastname: Halzen