Proton-proton forward scattering at the LHC

Abstract Recently the TOTEM experiment at the LHC has released measurements at s = 13 TeV of the proton-proton total cross section, σ t o t , and the ratio of the real to imaginary parts of the forward elastic amplitude, ρ. Since then an intense debate on the C-parity asymptotic nature of the scattering amplitude was initiated. We examine the proton-proton and the antiproton-proton forward data above 10 GeV in the context of an eikonal QCD-based model, where nonperturbative effects are readily included via a QCD effective charge. We show that, despite an overall satisfactory description of the forward data is obtained by a model in which the scattering amplitude is dominated by only crossing-even elastic terms, there is evidence that the introduction of a crossing-odd term may improve the agreement with the measurements of ρ at s = 13 TeV. In the Regge language the dominant even(odd)-under-crossing object is the so called Pomeron (Odderon).