Trigger and identification strategies for the search of Higgs boson pair production in the bbττ final state in the ATLAS experiment

Measuring the Higgs boson self-coupling is one of the primary objectives of the High Luminosity Large Hadron Collider (HL-LHC). Optimizing and upgrading the sensitivity to its signals is therefore crucial. During Run 2, the LHC achieved an integrated luminosity of 140 fb−1 for proton-proton collisions at 13 TeV, and this figure is expected to at least double by the end of the ongoing Run 3. De spite this increase, the low di-Higgs production cross-section requires significantly higher data statistics to observe this process. Hence, improving signal acceptance and efficiency, starting with enhanced trigger selections, is essential to reducing the necessary data volume for this measurement. This paper presents the latest results of an ongoing study focused on optimizing the trade-off between acceptance in the bbττ channel and the total trigger rate within the ATLAS experiment’s High-Level trigger. A notable advancement in this research is the introduction of a new b+τ trigger, which offers a superior efficiency-rate trade off compared to previous upgrades. Additionally, enhancements in identification algorithms through the inclusion of new variables have significantly improved background rejection power. These improvements are part of the comprehensive ATLAS effort to increase sensitivity to Higgs boson self-coupling measurements.