Confronting QCD Instantons with HERA Data

TL;DR

This paper investigates the potential to detect QCD instanton-induced processes in HERA deep-inelastic scattering data, setting upper limits on their occurrence and analyzing the sensitivity of various observables.

Contribution

It provides the first systematic analysis of HERA data's sensitivity to QCD instantons and establishes upper bounds on their contribution in specific kinematic regions.

Findings

Instanton processes constitute less than a few percent of DIS events.

Multiplicity distribution offers the most sensitive probe for instanton detection.

Established the first experimental upper limits on instanton-induced processes in HERA data.

Abstract

The sensitivity of existing HERA data on the hadronic final state in deep-inelastic scattering (DIS) to processes induced by QCD instantons is systematically investigated. The maximally allowed fraction of such processes in DIS is found to be on the percent level in the kinematic domain 0.0001 < x-Bjorken < 0.01 and 5 < Q squared < 100 GeV squared. The best limits are obtained from the multiplicity distribution.