Speaker
Description
The ATLAS search for pair-produced doubly charged Higgs bosons in multi-lepton final states using the full Run 2 dataset [Eur. Phys. J. C 83 (2023) 605] reports the strongest limits to date on the mass of such states, driven by an essentially background-free four-lepton channel. We show that the four-lepton signal efficiency implied by the auxiliary cutflow of that analysis exceeds a strict, mass-independent upper bound derived from the equal-branching-ratio assumption of the search, the leptonic τ branching fractions, and the ATLAS lepton reconstruction efficiencies. We show that this excess cannot be explained by hadronic τ or jet misidentification without invoking fake rates far above realistic values. Regenerating the signal independently and recomputing the exclusion limit with the corrected signal yields, the ATLAS background predictions, and the same CLs procedure implemented in pyhf, we obtain an expected limit lying systematically above the ATLAS expected limit by roughly a factor of two, shifting the expected lower mass bound from 1065 GeV to ∼ 950 GeV in the left-right symmetric type-II seesaw model, and from 880 GeV to ∼ 770 GeV in the Zee-Babu model.