Göttingen 2025 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 89: Axions/ALPs III

T 89.3: Vortrag

Freitag, 4. April 2025, 09:30–09:45, VG 0.110

Study of Higgs decays into long lived Axion-Like Particles with the ATLAS Experiment — •Janek Both, Christian Schmitt, Kristof Schmieden, and Volker Büscher — Johannes Gutenberg-Universität Mainz

Axion-Like Particles (ALP) or more generally, pseudoscalars that are gauge singlets under the Standard Model gauge group, appear in many well-motivated extensions of the Standard Model. These particles are naturally assumed to be light compared to the electroweak scale and might for example provide insides into the nature of dark matter. In scenarios where the ALP couples to the Higgs boson, collider searches can provide sensitivity to ALPs in the GeV range and thus offer a complementary approach to other experiments that mainly focus on lighter ALPs. Depending on the coupling strengths of the ALP, it might decay displaced from the primary vertex inside the calorimeters of the ATLAS detector. Such a signature would be almost background free and hence can be reconstructed with high efficiency. In this talk, a study of long-lived ALP decays inside the ATLAS calorimeter is presented and projected exclusion limits in the ALP mass and photon-coupling plane for an integrated luminosity of 1000 fb⁻¹ are shown. The future dataset will greatly improve upon the existing ATLAS run-2 and run-3 analyses, which focus on displaced ALP decays within the tracking system.

Keywords: Axion-Like particles; BSM Physics; ATLAS Experiment; Long-lived particles