Hunting for QCD Instantons at the LHC in Events with Large Rapidity Gaps

TL;DR

This paper proposes a method to detect QCD instantons in diffractive LHC events with large rapidity gaps, using specific selection criteria to enhance the signal over background in low luminosity runs.

Contribution

It introduces a new search strategy for QCD instantons at the LHC, including optimized event selection and updated cross-section calculations, to improve detection prospects.

Findings

Signal exceeds background by at least a factor of 8 with chosen cuts.

Instanton production can be studied at low luminosity without pile-up issues.

Updated instanton cross-section computations support the search strategy.

Abstract

We outline a strategy of how to search for QCD instantons of invariant mass 20 -- 60 GeV in diffractive events in low luminosity runs at the LHC. We show that by imposing appropriate selection criteria on the final states, one can select the kinematic regime where the instanton signal exceeds the background by a factor of at least 8. In spite of the relatively strong cuts that we impose on the total transverse energy and the number of charged tracks, $\sum_i E_{T,i}>15$ GeV, $N_{\rm ch}>20$ measured within the $0<\eta<2$ interval and excluding events with high $p_{T}$ particles, the expected cross-section is sufficiently large to study the instanton production in the events with Large Rapidity Gaps at low luminosities, thus avoiding problems with pile-up. The paper also includes an updated computation of instanton cross-sections and other parameters relevant for the ongoing studies.