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Abstract Artificial Intelligence is poised to transform the design of complex, large-scale detectors like ePIC at the future Electron Ion Collider. Featuring a central detector with additional detecting systems in the far forward and far backward regions, the ePIC experiment incorporates numerous design parameters and objectives, including performance, physics reach, and cost, constrained by mechanical and geometric limits.This project aims to develop a scalable, distributed AI-assisted detector design for the EIC (AID(2)E), employing state-of-the-art multiobjective optimization to tackle complex designs. Supported by the ePIC software stack and usingGeant4simulations, our approach benefits from transparent parameterization and advanced AI features.The workflow leverages the PanDA and iDDS systems, used in major experiments such as ATLAS at CERN LHC, the Rubin Observatory, and sPHENIX at RHIC, to manage the compute intensive demands of ePIC detector simulations. Tailored enhancements to the PanDA system focus on usability, scalability, automation, and monitoring.Ultimately, this project aims to establish a robust design capability, apply a distributed AI-assisted workflow to the ePIC detector, and extend its applications to the design of the second detector (Detector-2) in the EIC, as well as to calibration and alignment tasks. Additionally, we are developing advanced data science tools to efficiently navigate the complex, multidimensional trade-offs identified through this optimization process. 

Abstract Data preservation is a mandatory specification for any present and future experimental facility and it is a cost-effective way of doing fundamental research by exploiting unique data sets in the light of the continuously increasing theoretical understanding. This document summarizes the status of data preservation in high energy physics. The paradigms and the methodological advances are discussed from a perspective of more than ten years of experience with a structured effort at international level. The status and the scientific return related to the preservation of data accumulated at large collider experiments are presented, together with an account of ongoing efforts to ensure long-term analysis capabilities for ongoing and future experiments. Transverse projects aimed at generic solutions, most of which are specifically inspired by open science and FAIR principles, are presented as well. A prospective and an action plan are also indicated. 

This paper presents a search for massive, charged, long-lived particles with the ATLAS detector at the Large Hadron Collider using an integrated luminosity of $$140~fb^{−1}$$ of proton-proton collisions at $$\sqrt{s}=13$$~TeV. These particles are expected to move significantly slower than the speed of light. In this paper, two signal regions provide complementary sensitivity. In one region, events are selected with at least one charged-particle track with high transverse momentum, large specific ionisation measured in the pixel detector, and time of flight to the hadronic calorimeter inconsistent with the speed of light. In the other region, events are selected with at least two tracks of opposite charge which both have a high transverse momentum and an anomalously large specific ionisation. The search is sensitive to particles with lifetimes greater than about 3 ns with masses ranging from 200 GeV to 3 TeV. The results are interpreted to set constraints on the supersymmetric pair production of long-lived R-hadrons, charginos and staus, with mass limits extending beyond those from previous searches in broad ranges of lifetime 

This report presents a comprehensive collection of searches for new physics performed by the ATLAS Collaboration during the Run~2 period of data taking at the Large Hadron Collider, from 2015 to 2018, corresponding to about 140~$$^{-1}$$ of $$\sqrt{s}=13$$~TeV proton--proton collision data. These searches cover a variety of beyond-the-standard model topics such as dark matter candidates, new vector bosons, hidden-sector particles, leptoquarks, or vector-like quarks, among others. Searches for supersymmetric particles or extended Higgs sectors are explicitly excluded as these are the subject of separate reports by the Collaboration. For each topic, the most relevant searches are described, focusing on their importance and sensitivity and, when appropriate, highlighting the experimental techniques employed. In addition to the description of each analysis, complementary searches are compared, and the overall sensitivity of the ATLAS experiment to each type of new physics is discussed. Summary plots and statistical combinations of multiple searches are included whenever possible. 

Top-quark pair production is observed in lead–lead ( $\mathrm{Pb}+\mathrm{Pb}$) collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$at the Large Hadron Collider with the ATLAS detector. The data sample was recorded in 2015 and 2018, amounting to an integrated luminosity of $1.9{\mathrm{nb}}^{-1}$. Events with exactly one electron and one muon and at least two jets are selected. Top-quark pair production is measured with an observed (expected) significance of 5.0 (4.1) standard deviations. The measured top-quark pair production cross section is ${\sigma }_{t\overline{t}}=3.6{}_{-0.9}^{+1.0}\left(\mathrm{stat}\right){}_{-0.5}^{+0.8}\left(\mathrm{syst}\right)\mathrm{\mu }\mathrm{b}$, with a total relative uncertainty of 31%, and is consistent with theoretical predictions using a range of different nuclear parton distribution functions. The observation of this process consolidates the evidence of the existence of all quark flavors in the preequilibrium stage of the quark-gluon plasma at very high energy densities, similar to the conditions present in the early Universe. © 2025 CERN, for the ATLAS Collaboration2025CERN 

A<sc>bstract</sc> A study of the Higgs boson decaying into bottom quarks (H→$$ b\overline{b} $$ $b\overline{b}$) and charm quarks (H→$$ c\overline{c} $$ $c\overline{c}$) is performed, in the associated production channel of the Higgs boson with aWorZboson, using 140 fb⁻¹of proton-proton collision data at$$ \sqrt{s} $$ $\sqrt{s}$= 13 TeV collected by the ATLAS detector. The individual production ofWHandZHwithH→$$ b\overline{b} $$ $b\overline{b}$is established with observed (expected) significances of 5.3 (5.5) and 4.9 (5.6) standard deviations, respectively. Differential cross-section measurements of the gauge boson transverse momentum within the simplified template cross-section framework are performed in a total of 13 kinematical fiducial regions. The search for theH→$$ c\overline{c} $$ $c\overline{c}$decay yields an observed (expected) upper limit at 95% confidence level of 11.5 (10.6) times the Standard Model prediction. The results are also used to set constraints on the charm coupling modifier, resulting in|κ_c| <4.2 at 95% confidence level. Combining theH→$$ b\overline{b} $$ $b\overline{b}$andH→$$ c\overline{c} $$ $c\overline{c}$measurements constrains the absolute value of the ratio of Higgs-charm and Higgs-bottom coupling modifiers (|κ_c/κ_b|) to be less than 3.6 at 95% confidence level. 

The ATLAS experiment has developed extensive software and distributed computing systems for Run 3 of the LHC. These systems are described in detail, including software infrastructure and workflows, distributed data and workload management, database infrastructure, and validation. The use of these systems to prepare the data for physics analysis and assess its quality are described, along with the software tools used for data analysis itself. An outlook for the development of these projects towards Run 4 is also provided. 

A<sc>bstract</sc> Differential measurements of Higgs boson production in theτ-lepton-pair decay channel are presented in the gluon fusion, vector-boson fusion (VBF),VHand$$ t\overline{t}H $$ $t\overline{t}H$associated production modes, with particular focus on the VBF production mode. The data used to perform the measurements correspond to 140 fb⁻¹of proton-proton collisions collected by the ATLAS experiment at the LHC. Two methods are used to perform the measurements: theSimplified Template Cross-Section(STXS) approach and anUnfolded Fiducial Differentialmeasurement considering only the VBF phase space. For the STXS measurement, events are categorized by their production mode and kinematic properties such as the Higgs boson’s transverse momentum ($$ {p}_{\textrm{T}}^{\textrm{H}} $$ $p_T^H$), the number of jets produced in association with the Higgs boson, or the invariant mass of the two leading jets (m_jj). For the VBF production mode, the ratio of the measured cross-section to the Standard Model prediction form_jj> 1.5 TeV and$$ {p}_{\textrm{T}}^{\textrm{H}} $$ $p_T^H$> 200 GeV ($$ {p}_{\textrm{T}}^{\textrm{H}} $$ $p_T^H$< 200 GeV) is$$ {1.29}_{-0.34}^{+0.39} $$ ${1.29}_{-0.34}^{+0.39}$($$ {0.12}_{-0.33}^{+0.34} $$ ${0.12}_{-0.33}^{+0.34}$). This is the first VBF measurement for the higher-$$ {p}_{\textrm{T}}^{\textrm{H}} $$ $p_T^H$criteria, and the most precise for the lower-$$ {p}_{\textrm{T}}^{\textrm{H}} $$ $p_T^H$criteria. Thefiducialcross-section measurements, which only consider the kinematic properties of the event, are performed as functions of variables characterizing the VBF topology, such as the signed ∆ϕ_jjbetween the two leading jets. The measurements have a precision of 30%–50% and agree well with the Standard Model predictions. These results are interpreted in the SMEFT framework, and place the strongest constraints to date on the CP-odd Wilson coefficient$$ {c}_{H\overset{\sim }{W}} $$ $c_{H\tilde{W}}$.