Recast of ATLAS-EXOT-2018-06

• ATLAS page: ATLAS-EXOT-2018-06
• ATLAS paper: arXiv:2102.10874
• HEPData: 1847779
• HackAnalysis name: ATLAS_EXOT_2018_06
• Signature: monojet

Validation for the HackAnalysis analysis is to appear; it was developed in parallel with the MadAnalysis version and is essentially identical.