Browsing by Author "Hirsch, Martin"

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    Heavy neutral leptons and top quarks in effective field theory
    (Springer Nature, 2025) Beltrán, Rebeca; Cottin Buracchio, Giovanna Francesca; Günther, Julian; Hirsch, Martin; Titov, Arsenii; Wang, Zeren S.
    We study the phenomenology of heavy neutral leptons (HNLs) at the LHC in effective field theory, concentrating on d = 6 operators with top quarks. Depending on the operator choice and HNL mass, the HNLs will be produced either from proton-proton collisions in association with a single top, or via non-standard decays of top quarks. For long-lived HNLs we estimate the sensitivity reach of different detectors to various operators with top quarks and the HNLs for the high-luminosity phase of the LHC. For certain operators, ATLAS and some far detectors (MATHUSLA and ANUBIS) will be able to probe the associated new-physics scale as large as 12 TeV and 4.5 TeV, respectively, covering complementary HNL-mass ranges.
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    Long-lived particle phenomenology in one-loop neutrino mass models with dark matter
    (2025) Arbeláez, Carolina; Cottin Buracchio, Giovanna; Helo, Juan C.; Hirsch, Martin; de Melo, Téssio B.
    Neutrino masses and dark matter (DM) might have a common origin. The scotogenic model can be considered the proto-type model realizing this idea, but many other variants exist. In this paper we explore the phenomemology of a particular DM neutrino mass model, containing a triplet scalar. We calculate the relic density and check for constraints from direct detection experiments. The parameter space of the model, allowed by these constraints, contains typically a long-lived or quasi-stable doubly charged scalar, that can be searched for at the LHC. We reinterpret existing searches to derive limits on the masses of the scalars of the model and estimate future sensitivities in the high-luminosity phase of the LHC. The searches we discuss can serve to constrain also many other 1-loop neutrino mass models.