Study of Background Estimation and B-Tagging Performance in the H→WW*→ℓνℓν Run 3 Analysis with the ATLAS Detector

Ijaz Ahmad^1,2*, Yun-Ju Lu¹, Song-Ming Wang¹

¹Institute Of Physics, Academia Sinica, Taipei, Taiwan
²Department of Physics, National Central University, Taoyuan, Taiwan

* Presenter:Ijaz Ahmad, email:i.ahmad@cern.ch

The decay of the Higgs boson to a pair of W bosons (H → WW* → ℓνℓν) provides one of the most sensitive probes of Higgs production and electroweak symmetry breaking. Using Run 3 proton–proton collision data at √s = 13.6 TeV recorded with the ATLAS detector, this analysis targets Higgs boson production through gluon–gluon fusion (ggF) and vector-boson fusion (VBF), with emphasis on events containing two jets, where both production modes contribute significantly.

The current study focuses on background estimation and validation in control regions, particularly for non-resonant WW processes using mT₂-based studies and for top-quark backgrounds through updated B-tagging performance checks in both signal and control regions. A comparative study of the GN2 and DL1r b-tagging algorithms is performed to quantify their effects on the signal efficiency.

By refining the two-jet event selection and exploring new discriminating variables, this work strengthens the precision of Higgs-boson cross-section measurements in the H → WW* channel using Run 3 data and establishes a robust foundation for subsequent Higgs-coupling studies within ATLAS.

Keywords: Higgs boson, H → WW* → ℓνℓν, ggF & VBF, B-tagging performance, Background estimation