We show how to obtain the leading energy dependence of hadronic total cross sections, in the framework of the nonperturbative approach to soft high-energy scattering based on Wilson-loop correlation functions, if certain nontrivial analyticity assumptions are satisfied. The total cross sections turn out to be of "Froissart" type, $\sigma_{\rm tot}^{(hh)}(s) \mathop\sim B\log^2 s$ for ${s \to \infty}$. We also discuss under which conditions the coefficient $B$ is universal, i.e., independent of the hadrons involved in the scattering process. In the most natural scenarios for universality, $B$ can be related to the stable spectrum of QCD, and is predicted to be $B_{\rm th}\simeq 0.22~{\rm mb}$, in fair agreement with experimental results. If we consider, instead, the stable spectrum of the quenched (i.e., pure-gauge) theory, we obtain a quite larger value $B^{(Q)}_{\rm th} \ge 0.42~{\rm mb}$, suggesting (quite surprisingly) large unquenching effects due to the sea quarks.
Autori interni: | |
Autori: | Matteo Giordano; Enrico Meggiolaro |
Titolo: | Hadronic total cross sections at high energy and the QCD spectrum |
Anno del prodotto: | 2014 |
Digital Object Identifier (DOI): | 10.1007/JHEP03(2014)002 |
Appare nelle tipologie: | 1.1 Articolo in rivista |