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...

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...

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. ...

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 12, 1468 (2025)

Volume 1 of the FCC Feasibility Report presents an overview of the physics case, experimental programme, and detector concepts for the Future Circular Collider (FCC). This volume outlines how FCC would address some of the most profound open questions in particle physics, from precision studies of...

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 ...

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...

Physical review letters 134 12 (2025)

A search is performed for dark matter particles produced in association with a resonantly produced pair of b-quarks with 30

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

A search for a dark photon, a new light neutral particle, which decays promptly into collimated pairs of electrons or muons is presented. The search targets dark photons resulting from the exotic decay of the Standard Model Higgs boson, assuming its production via the dominant gluon-gluon fusion...

The journal of high energy physics 02 2 (2025)

The paper presents a search for supersymmetric particles produced in proton-proton collisions at $ \sqrt{s} $ = 13 TeV and decaying into final states with missing transverse momentum and jets originating from charm quarks. The data were taken with the ATLAS detector at the Large Hadron Collider at...

The journal of high energy physics 03 3 (2025)

A search for exotic decays of the 125 GeV Higgs boson into a pair of new spin-0 particles, H → aa, where one decays into a photon pair and the other into a τ-lepton pair, is presented. Hadronic decays of the τ-leptons are considered and reconstructed using a dedicated tagger for collimated...

Physical review. D 111 7 (2025)

Charged Higgs bosons produced either in top-quark decays or in association with a top quark, subsequently decaying via H±→τ±ντ, are searched for in 140  fb-1 of proton-proton collision data at s=13  TeV recorded with the ATLAS detector. Depending on whether the top quark is produced...

Physical review letters 134 14 (2025)

Top-quark pair production is observed in lead-lead (Pb+Pb) collisions at sqrt[s_{NN}]=5.02  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  nb^{-1}. Events with exactly one electron and...

The journal of high energy physics 03 3 (2025)

Differential measurements of Higgs boson production in the τ-lepton-pair decay channel are presented in the gluon fusion, vector-boson fusion (VBF), VH and $ t\overline{t}H $ associated production modes, with particular focus on the VBF production mode. The data used to perform the measurements...

The journal of high energy physics 02 2 (2025)

A search for the production of top-quark pairs with the same electric charge (tt or $ \overline{tt} $) is presented. The analysis uses proton-proton collision data at $ \sqrt{s} $ = 13 TeV, recorded by the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 140 ...

The journal of high energy physics 02 2 (2025)

A search for T and Y vector-like quarks produced in proton-proton collisions at a centre-of-mass energy of 13 TeV and decaying into Wb in the fully hadronic final state is presented. The search uses 139 fb$^{−1}$ of data collected by the ATLAS detector at the LHC from 2015 to 2018. The final...

Physical review letters 135 23, 231802 (2025)

A search for the dimuon decay of the Higgs boson is presented based on pp collision data recorded by ATLAS during Run 3 of the Large Hadron Collider, corresponding to an integrated luminosity of 165  fb^{-1} at sqrt[s]=13.6  TeV. To enhance the sensitivity, the results are combined with...

European physical journal. C, Particles and fields 85 12, 1397 (2025)

ATLAS, a general-purpose experiment at the Large Hadron Collider (LHC), makes use of a large internationally-distributed computing infrastructure, including over $10^6$ TB of managed data on disk and tape and almost one million simultaneously running CPU cores. Upgrades for the High-Luminosity LHC...

Physics letters. B 860, 139177 (2025)

Inclusive cross-sections for top-quark pair production in association with charm quarks are measured with proton–proton collision data at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 140 fb⁻¹, collected with the ATLAS experiment at the LHC between...

Physics letters. B 860, 139137 (2025)

A combination of searches for singly and doubly charged Higgs bosons, H± and H±±, produced via vector-boson fusion is performed using 140 fb⁻¹ of proton–proton collisions at a centre-of-mass energy of 13 TeV, collected with the ATLAS detector during Run 2 of the Large Hadron...

European physical journal. C, Particles and fields 85 12, 1441 (2025)

Processes with $\tau $-leptons in the final state are important for Standard Model measurements and searches for physics beyond the Standard Model. The ATLAS experiment at the Large Hadron Collider observes $\tau $-leptons produced in proton–proton collisions only through their decay products....

European physical journal. C, Particles and fields 85 12, 1437 (2025)

A search for R-parity-conserving supersymmetry in events with large missing transverse momentum, jets and at least one hadronically decaying $τ$-lepton is presented. Both gluino and squark pair production are considered, with the cascade decay of each gluino or squark producing either a...

The journal of high energy physics 04 4 (2025)

A study of the Higgs boson decaying into bottom quarks (H → $ b\overline{b} $) and charm quarks (H → $ c\overline{c} $) is performed, in the associated production channel of the Higgs boson with a W or Z boson, using 140 fb$^{−1}$ of proton-proton collision data at $ \sqrt{s} $ = 13 TeV...

European physical journal. C, Particles and fields 85 4 (2025)

The Lund jet plane (LJP) is measured for the first time in $t\bar{t}$ events, using 140 $\textrm{fb}^{-1}$ of $\sqrt{s} = 13$ TeV pp collision data collected with the ATLAS detector at the LHC. The LJP is a two-dimensional observable of the sub-structure of hadronic jets that acts as a proxy for...

European physical journal. C, Particles and fields 85 5 (2025)

This paper describes an algorithm for reconstructing and identifying a highly collimated hadronically decaying $\tau $-lepton pair with low transverse momentum. When two $\tau $-leptons are highly collimated, their visible decay products might overlap, degrading the reconstruction performance for...

The journal of high energy physics 05 5 (2025)

A search for pair production of vector-like leptons coupling to first- and second-generation Standard Model leptons is presented. The search is based on a dataset of proton-proton collisions at $ \sqrt{s} $ = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider,...

Physics letters. B 867, 139608 (2025)

The mass of the top quark is measured using top-antitop-quark pair events with high transverse momentum top quarks. The dataset, collected with the ATLAS detector in proton--proton collisions at $\sqrt{s}=13$ TeV delivered by the Large Hadron Collider, corresponds to an integrated luminosity of 140 ...

European physical journal. C, Particles and fields 85 5 (2025)

A search is presented for a heavy scalar (H) or pseudo-scalar (A) predicted by the two-Higgs-doublet models, where the H/A is produced in association with a top-quark pair $(t\bar{t}H/A),$ and with the H/A decaying into a $t\bar{t}$ pair. The full LHC Run 2 proton–proton collision data collected...

Physics letters. B 866, 139527 (2025)

A search for the production of three massive vector bosons, $VVZ (V=W, Z)$, in proton-proton collisions at $\sqrt{s} = 13$ TeV is performed using data with an integrated luminosity of $140$ fb$^{-1}$ recorded by the ATLAS detector at the Large Hadron Collider. Events produced in the leptonic final...

The journal of high energy physics 05 5 (2025)

A measurement of the ratio of the branching fractions, R$_{τ/e}$ = B(W → τν)/B(W → eν), is performed using a sample of W bosons originating from top-quark decays to final states containing τ-leptons or electrons. This measurement uses pp collisions at $ \sqrt{s} $ = 13 TeV, collected by...

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

A set of measurements for the production of a $W$-boson in association with high-transverse-momentum jets is presented using 140 fb$^{-1}$ of proton–proton collision data at a centre-of-mass energy of $\sqrt{s}=13$ TeV collected by the ATLAS detector at the LHC. The measurements are performed in...

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

High precision single-differential $W^\pm$-boson production cross-sections as a function of electron or muon transverse momentum $p_\mathrm{T}$ or their pseudorapity $\eta$, as well as double-differential cross-sections as functions of these variables, are measured in proton-proton collisions at...

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

A measurement of the $B^{0}$ meson lifetime using $ B^{0} \rightarrow J/\psi K^{*0} $ decays in data from 13 $\text {TeV}$ proton–proton collisions with an integrated luminosity of $ 140~\mathrm {fb^{-1}} $ recorded by the ATLAS detector at the LHC is presented. The measured effective lifetime is ...

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...