Theoretical considerations on multiparton interactions in QCD

TL;DR

This paper explores the theoretical aspects of multiple hard scatterings in QCD, addressing their structure, correlations, and evolution, and discusses challenges like divergences and double counting in current models.

Contribution

It provides a detailed analysis of the theoretical framework for multiparton interactions, highlighting issues and proposing directions for refinement and constraints.

Findings

Small-distance two-parton distributions cause divergences.

Double counting issues arise in current models.

Connecting distributions with lattice calculations offers potential constraints.

Abstract

We investigate several ingredients for a theory of multiple hard scattering in hadron-hadron collisions. Issues discussed include the space-time structure of multiple interactions, their power behavior, spin and color correlations, interference terms, scale evolution and Sudakov logarithms. We discuss possibilities to constrain multiparton distributions by lattice calculations and by connecting them with generalized parton distributions. We show that the behavior of two-parton distributions at small interparton distances leads to problems with ultraviolet divergences and with double counting, which requires modification of the presently available theoretical framework.