Multi-parton correlations and "exclusive" cross sections
G. Calucci, D. Treleani
TL;DR
The paper investigates how exclusive multi-parton cross sections, up to triple collisions, encode non-perturbative correlations in the hadron structure, beyond the usual inclusive cross sections. It develops a generating-functional formalism incorporating two-body transverse correlations and derives finite relations between inclusive and exclusive observables, introducing parameters like $ abla_{eff}$ and the dimensionless $ au$ that characterize double- and triple-parton scattering. Through three tractable transverse-space models—Gaussian, exponential, and a superposition of Poissonians—the authors provide analytic or semi-analytic expressions for $ abla_{eff}$ and $ au$ as functions of correlation length and strength, illustrating how measured exclusive cross sections can constrain multi-parton correlations. The work highlights that exclusive measurements offer a direct route to map non-perturbative hadron structure at the LHC, while also signaling the potential need for momentum-space correlations to fully explain observed cross sections such as $ abla_{eff}$.
Abstract
In addition to the inclusive cross sections discussed within the QCD-parton model, in the regime of multiple parton interactions, different and more exclusive cross sections become experimentally viable and may be suitably measured. Indeed, in its study of double parton collisions, the quantity measured by CDF was an "exclusive" rather than an inclusive cross section. The non perturbative input to the "exclusive" cross sections is different with respect to the non perturbative input of the inclusive cross sections and involves correlation terms of the hadron structure already at the level of single parton collisions. The matter is discussed in details keeping explicitly into account the effects of double and of triple parton collisions.