Narrow Results

Central production of lepton–antilepton pairs (e⁺e^- and μ⁺μ^-) and heavy quark composite states (charmonia and bottomonia) in diffractive proton collisions (proton momenta transferred |q_⊥| ~ m/ln s) are studied at ultrahigh energies (ln s ≫ 1), where σ_tot(pp^±) ~ ln^N s with 1 ≲ N ≲ 2. The pp^±-rescattering corrections, which are not small, are calculated in terms of the K-matrix approach modified for ultrahigh energies. Two versions of hadron interactions are considered in detail: the growth (i) σ_tot(pp^±) ~ ln² s, σ_inel(pp^±) ~ ln² s within the black disk mode and (ii) σ_tot(pp^±) ~ ln² s, σ_inel(pp^±) ~ ln s within the resonant disk mode. The energy behavior of the diffractive production processes differs strongly for these modes, thus giving a possibility to distinguish between the versions of the ultrahigh energy interactions.

On the basis of requirements of unitarity and analyticity we analyze the real and imaginary parts of the scattering amplitude at recent ultrahigh energies, $\text{1–100}\mathrm{\text{TeV}}$. The predictions for the region $\sqrt{s}>100\mathrm{\text{TeV}}$ and $q^2<0.4{\mathrm{\text{GeV}}}^2$ are given supposing the black disk asymptotic regime. It turns out that the real part of the amplitude is concentrated in the impact parameter space at the border of the black disk.