The ATLAS Roma1 group studies the properties of the Higgs boson through precision measurements and dedicated searches: rare decays, Higgs pair production (di-Higgs), and production associated with top quarks (ttH).
H → μμ: evidence
Combining Run-3 and Run-2, ATLAS achieved 3.4σ evidence for the decay of the Higgs boson into a pair of muons, thereby measuring its coupling to second-generation leptons.
Roma1 contribution: muon quality, background modeling, ggF/VBF categories, and combined fit.
Di-Higgs & HH→bbττ
Di-Higgs searches probe the Higgs boson’s self-coupling (κλ), a process predicted by the Standard Model but not yet observed. The bbττ channel offers leading sensitivity among single channels and is therefore of prime interest.
Roma1 contribution: τ reconstruction/ID, fake-factor, b-tagging and ML, VBF/boosted categories, MVA optimization, κλ scan.
Higgs-top coupling
Through the analysis of the ttH(bb) process, ATLAS achieved a direct measurement of the top–Higgs coupling with 4.6σ evidence, yielding the most precise single-channel determination of this coupling.
Roma1 contribution: advanced b-tagging, top-background modeling, neural networks, and STXS measurements.
Fonti principali: evidenza H→μμ (ATLAS, arXiv:2507.03595; Briefing), di-Higgs combinato e canali bbττ/bbγγ (arXiv:2404.12660; arXiv:2507.03495), ttH(bb) Run-2 (Briefing; arXiv:2407.10904).