Steven Schramm

Antti Pietari Pirttikoski

Thèse, 177 (2026)

The Large Hadron Collider provides proton-proton collisions at the highest energies ever achieved in a laboratory setting, enabling precision tests of the Standard Model and searches for new physics. Many of the resulting final states are hadronic and are reconstructed as jets, whose measurement...

Léon Bozianu

Thèse, 256 (2026)

The trigger and data acquisition system is an essential and evolving component of the ATLAS detector. The sequential hardware and software triggers are responsible for the real-time reconstruction of all physics signatures of interest and the selection of events based on diverse trigger hypotheses. ...

Björn Penning, Nicolas Angelides, Laura Baudis, Harvey Birch, Abigail Flowers, Florian Jörg, Alexander Kavner, Marcelle Soares-Santos, Aravind Remesan Sreekala, Johannes Wüthrich, Guandi Zhao, Chiara Capelli, John Clinton, Jose Cuenca García, Paolo Crivelli, Domenico Giardini, Evangelos-Leonidas Gkougkousis, Yacine Haddad, Marian Hertrich, Rebecca Hochreutener, Luisa Hötzsch, Philippe Jetzer, Ben Kilminster, Boris Korzh, Frédérick Massin, Knut Dundas Morå, Margherita Noia, Francesco Piastra, Christian Regenfus, Federico Sanchez Nieto, Steven Schramm, Francesco Riva, Serhan Tufanli, Michele Weber, Stefan Wiemer and Mathilde Wimez

European physical journal. C, Particles and fields 86 7, 866 (2026)

Underground laboratories provide the ultra-low background and low-vibration environments essential for rare-event searches, gravitational-wave detection, and quantum-sensing technologies. We report a comprehensive environmental characterisation of the Bedretto tunnel in Ticino, Switzerland, a site...

Mario Alves Cardoso

Thèse, 138 (2026)

This thesis presents a novel methodology within the ATLAS experiment that exploits the large number of recorded untriggered pp interactions, commonly referred to as pile-up, to construct a dedicated low-p_T dataset. By treating each additional inelastic collision in a recorded bunch...

The journal of high energy physics 01, 53 (2025)

A search is performed for light, spin-0 bosons decaying into two photons in the 66 to 110 GeV mass range, using 140 fb$^{−1}$ of proton-proton collisions at $ \sqrt{s} $ = 13 TeV produced by the Large Hadron Collider and collected by the ATLAS detector. Multivariate analysis techniques are used...

European physical journal. C, Particles and fields 85 6 (2025)

This paper presents the reconstruction of missing transverse momentum ($p_{\text {T}}^{\text {miss}}$) in proton–proton collisions, at a center-of-mass energy of 13 TeV. This is a challenging task involving many detector inputs, combining fully calibrated electrons, muons, photons, hadronically...

Physics letters. B 865, 139472 (2025)

A search is conducted for a new scalar boson S, with a mass distinct from that of the Higgs boson, decaying promptly into four leptons (ℓ=e, μ) via an intermediate state containing two on-shell, promptly decaying new spin-1 bosons Zd: S→ZdZd→4ℓ, where the Zd boson has a mass between 15 and ...

The journal of high energy physics 8 8, 142 (2025)

Measurements of W$^{+}$W$^{−}$ → e$^{±}$νμ$^{∓}$ν production cross-sections are presented, providing a test of the predictions of perturbative quantum chromodynamics and the electroweak theory. The measurements are based on data from pp collisions at $ \sqrt{s} $ = 13 TeV recorded by the...

European physical journal. C, Particles and fields 85 6 (2025)

This paper presents a new $\tau $-lepton reconstruction and identification procedure at the ATLAS detector at the Large Hadron Collider, which leads to significantly improved performance in the case of physics processes where a highly boosted pair of $\tau $-leptons is produced and one $\tau...

The journal of high energy physics 11 11, 68 (2025)

Measurements of integrated and differential cross-sections for W$^{±}$Z production in proton-proton collisions are presented. The data collected by the ATLAS detector at the Large Hadron Collider from 2015 to 2018 at a centre-of-mass energy of $ \sqrt{s}=13 $ TeV are used, corresponding to an...

The journal of high energy physics 10 10, 70 (2025)

A search for the production of a Higgs boson in association with a single top quark, tH, is presented. The analysis uses proton-proton collision data corresponding to an integrated luminosity of 140 fb$^{−1}$ at a centre-of-mass energy of 13 TeV, collected by the ATLAS detector at the LHC. The...

Physics letters. B 870, 139898 (2025)

A measurement of off-shell Higgs boson production is performed in the H* → WW channel. The measurement uses a proton–proton collision dataset with an integrated luminosity of 140 fb−1 collected at a centre-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. Final...

Physics letters. B 870, 139892 (2025)

This letter reports the measurement of double parton scattering in same-sign W boson pair production with the ATLAS detector. The data set used corresponds to an integrated luminosity of 140 fb−1 of proton–proton collisions at a center-of-mass energy of 13 TeV, collected during Run 2 of the...

European physical journal. C, Particles and fields 85 9, 927 (2025)

The jet energy calibration and its uncertainties are derived from measurements of the calorimeter response to single particles in both data and Monte Carlo simulation using proton-proton collisions at $\sqrt{s} = 13$ TeV collected with the ATLAS detector during Run 2 at the Large Hadron Collider....

Physical review letters 135 11, 111802 (2025)

This Letter reports the first evidence of electroweak production of same-sign W boson pairs where at least one of the W bosons is longitudinally polarized and the most stringent constraint to date for the production of two longitudinally polarized same-sign W bosons. The dataset used corresponds to ...

The journal of high energy physics 2025, 12 (2025)

A search for single production of a vector-like quark Q, which could be either a singlet T, with charge $ \frac{2}{3} $, or a Y from a (T, B, Y) triplet, with charge $ -\frac{4}{3} $, is performed using data from proton-proton collisions at a centre-of-mass energy of 13 TeV. The data correspond to...

The journal of high energy physics 12 12, 23 (2025)

A measurement of the top-quark pole mass $ {m}_t^{\textrm{pole}} $ is presented in $ t\overline{t} $ events with an additional jet, $ t\overline{t} $ + 1-jet, produced in pp collisions at $ \sqrt{s}=13 $ TeV. The data sample, recorded with the ATLAS experiment during Run 2 of the LHC, corresponds...

The journal of high energy physics, 180 (2025)

This paper presents a search for physics beyond the Standard Model targeting a heavy resonance visible in the invariant mass of the lepton-jet system. The analysis focuses on final states with a high-energy lepton and jet, and is optimised for the resonant production of leptoquarks — a novel...

Physical review. D. 112 7, 44 (2025)

A search for exotic decays of the Higgs boson H into new scalar or pseudoscalar particles that subsequently decay into b-quarks is presented. The search considers ZH production with several decay scenarios for the Higgs boson; first to a pair of identical scalars, H→2a→4b, second to a pair of...

Physical review. D. 112 7, 34 (2025)

An anomaly detection search for narrow-width resonances beyond the Standard Model that decay into a pair of jets is presented. The search is based on 139 fb-1 of proton-proton collisions at s=13 TeV recorded during 2015–2018 with the ATLAS detector at the Large Hadron Collider. The analysis is...

The journal of high energy physics 10 10 (2025)

The CP properties of the Higgs boson are studied in the vector-boson fusion production mode. The analysis exploits the decay mode of the Higgs boson into two τ-leptons using 140 fb$^{−1}$ of proton-proton collision data at $ \sqrt{s}=13 $ TeV collected by the ATLAS experiment at the Large Hadron ...

The journal of high energy physics 10 10 (2025)

The production cross-section of high-mass τ-lepton pairs is measured as a function of the dilepton visible invariant mass, using 140 fb$^{−1}$ of $ \sqrt{s}=13 $ TeV proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider. The measurement agrees with the...

The journal of high energy physics 09 9, 49 (2025)

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...

Physical review. D. 112 9, 30 (2025)

This article reports on a search for dijet resonances using 132 fb-1 of pp collision data recorded at s=13 TeV by the ATLAS detector at the Large Hadron Collider. The search is performed solely on jets reconstructed within the ATLAS trigger to overcome bandwidth limitations imposed on conventional...

European physical journal. C, Particles and fields 85 11, 42 (2025)

A search for pair-production of vector-like leptons is presented, considering their decays into a third-generation Standard Model (SM) quark and a vector leptoquark ($U_1$) as predicted by an ultraviolet-complete extension of the SM, referred to as the '4321' model. Given the assumed decay of $U_1$ ...

European physical journal. C, Particles and fields 85 11, 44 (2025)

A calibration of the ATLAS flavour-tagging algorithms using a new calibration procedure based on optimal transportation maps is presented. Simultaneous, continuous corrections to the b-jet, c-jet, and light-flavour jet classification probabilities from jet-tagging algorithms in simulation are...

Physical review. D. 112 9 (2025)

A search for events with one displaced vertex from long-lived particles using data collected by the ATLAS detector at the Large Hadron Collider is presented, using 140 fb-1 of proton-proton collision data at s=13 TeV recorded in 2015–2018. The search employs techniques for reconstructing vertices ...

European physical journal. C, Particles and fields 85 7 (2025)

Jets with different radius parameters R are an important tool for probing quantum chromodynamics processes at different angular scales. Jets with small $R=0.2$ are instrumental in measurements of the substructure of large-R jets resulting from collimated hadronic decays of energetic W, Z, and Higgs ...

Physical review. D 112 1 (2025)

A search for cascade decays of charged sleptons and sneutrinos using final states characterized by three leptons (electrons or muons) and missing transverse momentum is presented. The analysis is based on a dataset with 140  fb-1 of proton-proton (pp) collisions at a center-of-mass energy of...

The journal of high energy physics 07 7 (2025)

This paper presents a first measurement of the cross-section for the charged-current Drell-Yan process pp → W$^{±}$ → ℓ$^{±}$ν above the resonance region, where ℓ is an electron or muon. The measurement is performed for transverse masses, $ {m}_{\textrm{T}}^{\textrm{W}} $, between 200...

Physical review. D 112 1 (2025)

A search for leptons displaced from the primary vertex is performed with the ATLAS detector at the Large Hadron Collider. The search includes the full proton-proton collision dataset collected during Run 2 at $\sqrt{s}=13$ TeV and a partial dataset collected during Run 3 in 2022-2023 at...

The journal of high energy physics 07 7 (2025)

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...

Physics letters. B 868, 139671 (2025)

A search for decays of the Higgs boson into a $Z$ boson and a light resonance, with a mass of 0.5-3.5 GeV, is performed using the full 140 fb$^{-1}$ dataset of 13 TeV proton-proton collisions recorded by the ATLAS detector during Run 2 of the LHC. Leptonic decays of the $Z$ boson and hadronic...

The journal of high energy physics 07 7 (2025)

The production of D$^{±}$ and $ {D}_s^{\pm } $ charmed mesons is measured using the D$^{±}$/$ {D}_s^{\pm } $→ ϕ(μμ)π$^{±}$ decay channel with 137 fb$^{−1}$ of $ \sqrt{s} $ = 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider during the...

Physics letters. B 868, 139680 (2025)

Measurements of jet substructure are key to probing the energy frontier at colliders, and many of them use track-based observables which take advantage of the angular precision of tracking detectors. Theoretical calculations of track-based observables require ‘track functions’, which...

The journal of high energy physics 08 8, 34 (2025)

Measurements of the total and differential Higgs boson production cross-sections, via WH and ZH associated production using H → WW$^{*}$ → ℓνℓν and H → WW$^{*}$ → ℓνjj decays, are presented. The analysis uses proton-proton events delivered by the Large Hadron Collider at a...

Malte Algren, Mario Alves Cardoso, Claire Antel, Konstantinos Axiotis, Léon Bozianu, Vilius Cepaitis, Allan Geoffrey Clark, Domenico Della Volpe, Mariia Drozdova, Lukas Ehrke, Didier Ferrere, Stefano Franchellucci, Alexander Froch, Tobias Golling, Sergio Gonzalez Sevilla, Daigo Harada, Giuseppe Iacobucci, Samuel Klein, Pantelis Kontaxakis, Matthew Leigh, Carlos Moreno Martinez, Ivan Oleksiyuk, Lorenzo Paolozzi, Antti Pietari Pirttikoski, Guillaume Quetant, Johnny Raine, Jorge Sabater Iglesias, Steven Schramm, Tomke Schroeer, Debajyoti Sengupta, Anna Sfyrla, Ondrej Theiner, Yusong Tian, Xin Wu and Stefano Zambito

Journal of instrumentation 20 03, P03002 (2025)

In 2022 and 2023, the Large Hadron Collider produced approximately two billion hadronic interactions each second from bunches of protons that collide at a rate of 40 MHz. The ATLAS trigger system is used to reduce this rate to a few kHz for recording. Selections based on hadronic jets, their...

Physics letters. B 871 139929, 17 (2025)

Measurements of jet substructure in Pb+Pb collisions provide key insights into the mechanism of jet quenching in the hot and dense QCD medium created in these collisions.This Letter presents a measurement of the suppression of large-radius jets with a radius parameter of R=1.0 and its dependence on ...

The journal of high energy physics 2025 11 (2025)

Physics letters. B 861, 139277 (2025)

This Letter presents a constraint on the total width of the Higgs boson (ΓH) using a combined measurement of on-shell Higgs boson production and the production of four top quarks, which involves contributions from off-shell Higgs boson-mediated processes. This method relies on the assumption that...

The journal of high energy physics 2025, 68 (2025)

This paper presents measurements of top-antitop quark pair ($ t\overline{t} $) production in association with additional b-jets. The analysis utilises 140 fb$^{−1}$ of proton–proton collision data collected with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13...

Physical review. D 112 1 (2025)

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. The ATLAS experiment dataset collected at the Large Hadron Collider from 2015 to...

The journal of high energy physics 07 7 (2025)

A search is performed for long-lived heavy neutral leptons (HNLs), produced through the decay of a W boson along with a muon or electron. Two channels are explored: a leptonic channel, in which the HNL decays into two leptons and a neutrino, and a semi-leptonic channel, in which the HNL decays into ...

The journal of high energy physics 08 8, 53 (2025)

This paper presents searches for the direct pair production of charged light-flavour sleptons, each decaying into a stable neutralino and an associated Standard Model lepton. The analyses focus on the challenging “corridor” region, where the mass difference, ∆m, between the slepton ($...

European physical journal. C, Particles and fields 85 8, 886 (2025)

A search for a pseudoscalar $a$ produced in association with a top-quark pair, or in association with a single top quark plus a $W$ boson, with the pseudoscalar decaying into b-quarks ($a\rightarrow b\bar{b}$), is performed using the full Run 2 data sample using a dileptonic decay mode signature....

European physical journal. C, Particles and fields 85 3 (2025)

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...

European physical journal. C, Particles and fields 85 12, 1434 (2025)

Measurements of $t\bar{t}\ell^{+}\ell^{-}$ production in the region of high dilepton invariant mass with effective field theory (EFT) interpretations are presented. They are performed using final states with three isolated leptons (electrons or muons) and are based on $\sqrt{s} = 13$ TeV...

European physical journal. C, Particles and fields 85 12 (2025)

Higgs boson production cross-sections via gluon–gluon fusion and vector-boson fusion in proton–proton collisions are measured in the $H\rightarrow WW^*\rightarrow \ell \nu \ell \nu $ decay channel. The Large Hadron Collider delivered proton–proton collisions at a centre-of-mass energy of...

The journal of high energy physics 02 2 (2025)

This article presents a search for a heavy charged Higgs boson produced in association with a top quark and a bottom quark, and decaying into a W boson and a 125 GeV Higgs boson h. The search is performed in final states with one charged lepton, missing transverse momentum, and jets using...

European physical journal. C, Particles and fields 85 2 (2025)

This paper reports the measurement of Higgs boson production in association with a $t\bar{t}$ pair in the $H\rightarrow b\bar{b}$ decay channel. The analysis uses 140 fb$^{-1}$ of 13 $\text {TeV}$ proton–proton collision data collected with the ATLAS detector at the Large Hadron Collider. The...