Notes on recasting the ATLAS-EXOT-2019-23 search for pairs of displaced hadronic jets in the ATLAS calorimeter

TL;DR

This paper validates a reinterpretation method for an ATLAS search targeting displaced hadronic jets from long-lived particles, providing an efficiency map and discussing its limitations and validation procedures.

Contribution

It introduces a validated efficiency map for recasting the ATLAS displaced jet search and discusses the limitations of current reinterpretation materials.

Findings

The efficiency map can recover ATLAS limits with simulated events.

Limitations exist in the current material for external validation.

Validation procedures reveal issues in recasting accuracy.

Abstract

This note describes the validation of material allowing the reinterpretation of an ATLAS search for decays of pair-produced neutral long-lived particles decaying in the hadronic part of the calorimeter, or at the edge of the electromagnetic calorimeter, using the full Run-2 ATLAS dataset. This reinterpretation material includes an efficiency map linking truth-level kinematic information (decay position, transverse momentum and decay products of the LLPs) to the probability of the reconstructed event being selected in the analysis signal region. In this document we describe the validation procedure, i.e. how the map was used to recover the limits presented in the ATLAS publication using events generated with MadGraph5_aMC@NLO and hadronised using Pythia8, and we identify some limitations of this approach. We moreover comment upon issues concerning the validation procedure itself, in particular with regards to whether or not the information included in the existing, published material allows for an external user to test recasting methods.