A search for dark matter produced in association with a dark Higgs boson decaying into a Higgs boson pair in 3b or 4b final states using <em>pp</em> collisions at $\sqrt{s}=13$ TeV with the ATLAS dete

A search is performed for dark matter particles produced in association with a resonant pair of Higgs bosons using 140 fb⁻¹ of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the Large Hadron Collider. This signature is expected in some extensions of the Standard Model predicting the production of dark matter particles, and is interpreted in terms of a dark Higgs model containing a Z′ mediator in which the dark Higgs boson s decays into a pair of Higgs bosons. The dark Higgs boson is reconstructed through final states with at least three b-tagged jets, produced by the pair of Higgs boson decays, in events with significant missing transverse momentum consistent with the presence of dark matter. The observed data are found to be in good agreement with Standard Model predictions, constraining scenarios with dark Higgs boson masses within the range of 250 to 400 GeV and Z′ mediators up to 2.3 TeV.. Authors: Aad, G. [Centre National de la Recherche Scientifique (CNRS), Marseille (France). Centre de Physique des Particules de Marseille (CPPM); Aix-Marseille Univ., Marseille (France); ATLAS Collaboration; et al.] (ORCID:0000000266654934); Aakvaag, E. [University of Bergen] (ORCID:0000000176161554); Abbott, B. [University of Oklahoma] (ORCID:0000000258882734); Abdelhameed, S. [New York University Abu Dhabi] (ORCID:0000000202875869); Abeling, K. [Georg-August-Universität Göttingen] (ORCID:0000000210021652). DOE Contract: AC02-05CH11231; FG02-03ER41244; SC0017996. Subjects: Dark Energy and Dark Matter; Experimental Particle Physics; Higgs physics; High-Energy Astrophysics; Particle Astrophysics; Particle Physics; Theoretical Particle Physics; hadron-hadron scattering