CERN Accelerating science

ATLAS Slides
Report number	ATL-PHYS-SLIDE-2025-412
Title	Search for new physics in final states with semi-visible jets or anomalous signatures using the ATLAS detector
Author(s)	Park, Ki Ryeong (Columbia University (US))
Corporate author(s)	The ATLAS collaboration
Collaboration	ATLAS Collaboration
Submitted to	The 32nd International Symposium on Lepton Photon Interactions at High Energies (Lepton Photon 2025), Madison, Wisconsin, Us, 25 - 29 Aug 2025
Submitted by	k.park@cern.ch on 29 Aug 2025
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; ATLAS
Free keywords	Experimental results ; Dark matter ; Dark sector ; Z' mediator ; Anomaly Detection ; Variational Autoencoder ; Particle Flow Network ; EXOTICS
Abstract	A search is presented for hadronic signatures of beyond the Standard Model (BSM) physics, with an emphasis on signatures of a strongly-coupled hidden dark sector accessed via resonant production of a Z' mediator using 140fb-1 of Run-2 pp collision data at 13 TeV. The Z' mediator is considered to decay to two dark quarks, each of which then hadronizes and decays to showers containing both dark and Standard Model particles, producing a topology of interacting and non-interacting particles within a jet known as "semi-visible". Machine learning methods are used to select events with semi-visible jets and reject the dominant background of mismeasured multijet events, including an anomaly detection approach to preserve broad sensitivity to a variety of BSM topologies.