Search for a new scalar decaying into new spin-1 bosons in four-lepton final states with the ATLAS detector

Abstract

A search is conducted for a new scalar boson 𝑆, with a mass distinct from that of the Higgs boson, decayingpromptly into four leptons (𝓁 = 𝑒, 𝜇) via an intermediate state containing two on-shell, promptly decaying newspin-1 bosons 𝑍d: 𝑆 RIGHTWARDS ARROW𝑍d𝑍d RIGHTWARDS ARROW4𝓁, where the 𝑍d boson has a mass between 15 and 300 GeV, and the 𝑆 bosonhas a mass between either 30 and 115 GeV or 130 and 800 GeV. The search uses proton-proton collision datacollected with the ATLAS detector at the Large Hadron Collider with an integrated luminosity of 139 fb-1 at acentre-of-mass energy of SQUARE ROOT𝑠 = 13 TeV. No significant excess above the Standard Model background expectationis observed. Upper limits at 95% confidence level are set on the production cross-section times branching ratio,𝜎(𝑔𝑔 RIGHTWARDS ARROW𝑆) x (𝑆 RIGHTWARDS ARROW𝑍d𝑍d RIGHTWARDS ARROW4𝓁), as a function of the mass of both particles, 𝑚𝑆 and 𝑚𝑍d.