Primary Vertex Selection in VBF Higgs to Invisibles at the HL-LHC with the ATLAS Experiment

TL;DR

This paper presents a novel vertex selection algorithm for VBF Higgs to invisible events at HL-LHC, utilizing ATLAS's forward tracking and pile-up mitigation techniques to enhance efficiency and robustness.

Contribution

The paper introduces a new vertex selection method that combines calorimeter and tracking data, improving pileup resilience and vertex efficiency in VBF Higgs analyses.

Findings

Vertex selection efficiency increased from 86% to 95%.

Algorithm is insensitive to pileup density.

Enhanced pile-up jet suppression methods implemented.

Abstract

ATLAS has developed a new approach for vertex selection in VBF invisible events at HL-LHC conditions, exploiting its new forward tracking capabilities, integrating calorimeter and tracking information to mitigate the impact of pileup vertex merging, and introducing a new way to apply pile-up jet suppression methods for the selection of VBF jets. The new algorithm is insensitive to pileup density and improves the average vertex selection efficiency from 86% to 95% under tight VBF event selection cuts.