Multiple Scattering, Underlying Event, and Minimum Bias

TL;DR

This paper reviews experimental evidence and theoretical models related to multiple scattering, underlying events, and minimum bias in high-energy collisions, highlighting discrepancies with traditional theories and discussing advanced concepts like color recombination and pomeron effects.

Contribution

It introduces new insights into the limitations of traditional models for multiple collisions and explores alternative theories involving color recombination and pomeron vertices.

Findings

Experimental data challenge traditional multiple collision models.

Evidence suggests strong effects from pomeron vertices and color recombination.

Theoretical discussions connect multiple collisions with unitarity and diffraction.

Abstract

In this talk I first discuss the experimental evidence for multiple scattering and the properties of the underlying event. The extensive analyses by Rick Field of data from CDF cannot be reconciled with traditional wisdom concerning multiple collisions and the AGK cutting rules. Data seem to imply some kind of color recombination or unexpectedly strong effects from pomeron vertices. I then discuss theoretical ideas concerning the relation between multiple collisions and unitarity: the AGK rules, IP loops, dipole cascade models and diffraction.