Double parton scatterings in high energy hadronic collisions
G. Calucci, D. Treleani
TL;DR
The paper investigates double parton scatterings in high-energy hadronic collisions, prompted by CDF's observation of a small sigma_eff that signals nontrivial two-body parton correlations in the proton. It builds a theoretical framework based on D_2 and generating functionals to describe the semi-hard cross section sigma_H, incorporating two-body correlations, and clarifies how these correlations modify the relationship between sigma_D, sigma_H, and sigma_eff. The analysis shows that correlations can reduce sigma_eff through changes in the parton-number distribution or non-factorized x-dependence, and proposes measuring sigma_H and triple-parton cross sections to constrain the correlation parameters and reveal the proton’s transverse structure. The work emphasizes that multiple parton interactions offer a direct probe of the three-dimensional parton structure of the proton, beyond conventional one-body PDFs.
Abstract
CDF has recently measured a large number of double parton scatterings. The observed value of $σ_{eff}$, the non perturbative parameter which characterizes the process, is considerably smaller as compared with the naive expectation. The small value of $σ_{eff}$ is likely to be an indication of the importance of the two-body parton correlations in the many-body parton distributions of the proton.