ATLAS Live talk: How does ATLAS study heavy-ion collisions?

On 14 September at 6pm CEST, Dr. Martin Rybar and Dr. Peter Steinberg will give a live public talk on the ATLAS Youtube Channel on how the ATLAS experiment records heavy-ion collisions.

News | 14 Sep 2023

ATLAS observes top quarks in heavy-ion collisions

The ATLAS Collaboration at CERN observes the production of top-quark pairs in proton-lead ion collisions. ATLAS’ new result confirms and builds upon an earlier observation made by the CMS Collaboration, expanding it into a new decay channel.

Physics Briefing | 06 Sep 2023

When jets go dark

For the very first time, the ATLAS Collaboration has searched for dark jets that closely resemble QCD jets. Instead of originating from Standard-Model particles, these dark jets would be produced through a new, heavy particle called the Z' boson.

Physics Briefing | 06 Sep 2023

Summary of new ATLAS results from Quark Matter 2023

The ATLAS Collaboration has prepared a variety of new results for the Quark Matter conference, focusing on the study of collisions involving lead ions, xenon, and lead ions with protons.

News | 04 Sep 2023

ATLAS measures ZZ production using Run-3 data and a new slim data format

The ATLAS Collaboration has just released a new measurement of the production cross section of two Z bosons. This highlight result examines data collected during Run 3 of the LHC and pioneers the use of PHYSLITE, a new, reduced data format that requires significantly less storage.

Physics Briefing | 25 Aug 2023

ATLAS searches for new phenomena using unsupervised machine learning for anomaly detection

In a new paper submitted to Phys. Rev. Lett., the ATLAS Collaboration pioneers the use of unsupervised machine learning to search for anomalous collision events which could be from new-physics phenomena.

Physics Briefing | 24 Aug 2023

Quest for the curious magnetic monopole continues

In a new study presented at the EPS-HEP 2023 conference, the ATLAS Collaboration combed through the full LHC Run-2 dataset (recorded 2015-2018) in search for magnetic monopoles and HECOs (see Figure 1). The result places some of the tightest limits yet on the production rate of magnetic monopoles.

Physics Briefing | 23 Aug 2023

ATLAS releases comprehensive review of supersymmetric dark matter

In new results presented today, the ATLAS Collaboration provides its most comprehensive overview of the searches for weakly-interacting supersymmetric particles. By developing new search algorithms and exploiting machine learning techniques, researchers have probed deep into this difficult-to-reach territory.

Physics Briefing | 22 Aug 2023

Three’s no crowd: ATLAS measures tri-boson production

The ATLAS Collaboration has announced the first observation of two different tri-boson processes: the simultaneous production of a W boson with two photons (Wγγ) and the production of a W boson, a Z boson and a photon (WZγ). The production of a Z boson with two photons (Zγγ) was first observed in 2016 using data from LHC Run 1 (2010-2013). In a new publication, the ATLAS Collaboration expanded the scope of this initial observation using Run 2 data.

Physics Briefing | 18 Aug 2023

ATLAS hunts for new physics in the scattering of W bosons

Vector boson scattering processes play a special role within the Standard Model, as they are closely related to the Higgs mechanism and can proceed via an exchange of a Higgs boson. By studying these processes, ATLAS physicists are exploring multiple new-physics models, including anomalous self-interactions of the W bosons and extended Higgs sector with additional Higgs bosons.

Physics Briefing | 08 Aug 2023

Machine learning is revolutionising our understanding of particle “jets”

This week, ATLAS physicists presented four exciting new results about jet tagging using AI algorithms at the BOOST 2023 conference held at Lawrence Berkeley National Lab (USA).

Physics Briefing | 03 Aug 2023

Signal and noise

The ATLAS Collaboration has released two new results explaining how detector timing measurements and calorimeter signal calibration using artificial intelligence (AI) are being used to further improve the quality of data recorded by the experiment.

Physics Briefing | 01 Aug 2023

Summary of new ATLAS results from BOOST 2023

The 15th International Workshop on Boosted Object Phenomenology, Reconstruction, Measurements, and Searches at Colliders (BOOST 2023) kicks off today in Lawrence Berkeley National Lab, California (USA). The conference brings together experts from the LHC experiments and the theory community to discuss new approaches for using “jets” of particles in studies of Quantum Chromodynamics (QCD) and searches physics beyond the Standard Model.

News | 31 Jul 2023

ATLAS sets record precision on Higgs boson’s mass

The new result is the most precise determination of the Higgs-boson mass yet, achieving a remarkable accuracy of 0.09% for this fundamental parameter.

Press Statement | 21 Jul 2023

ATLAS measures Higgs boson mass with unprecedented precision

This week, at the Lepton-Photon Conference in Melbourne (Australia), the ATLAS Collaboration presented its measurement of the Higgs-boson mass in studies of Higgs decays to two photons using the full LHC Run 2 dataset (“H→yy” or the diphoton channel), and a new combination of this measurement with the 2022 measurement of the Higgs-boson mass in studies of the Higgs decays to four leptons (the “H→4l channel”).

Physics Briefing | 21 Jul 2023

Summary of new ATLAS results from 2023 summer conferences

The summer conference season is here! While for some, summer means slowing down – for ATLAS researchers, it means the start of new conferences, with more new results to be presented! This season, experimental physics and theorists will be traveling to Melbourne, Australia, for the International Symposium on Lepton Photon Interactions at High Energies (Lepton Photon), and to Hamburg, Germany, for the European Physical Society Conference on High Energy Physics ( EPS-HEP).

News | 17 Jul 2023

Giving collisions a new shape

When studying the shape of LHC collision events, physicists ask: how similar or different is their energy flow? The ATLAS Collaboration recently published a measurement of new collision event shapes in high-energy multijet events at the LHC.

Physics Briefing | 14 Jul 2023

ATLAS highlights from LHCP 2023

Over 300 physicists travelled to Belgrade (Serbia) for LHCP’s long-awaited return to in-person gatherings. Scientists from the ATLAS Collaboration presented several new results at the LHCP conference. These newly released results cover a broad range of physics topics, including precision measurements of the W± and Z bosons, evidence of the Higgs-boson decay into a Z boson and a photon, and searches for a new scalar particle.

News | 16 Jun 2023

Not a jet all the way: is dark matter hiding in plain sight?

What happens if dark-matter particles are produced inside a jet of Standard-Model particles? This leads to a novel detector signature known as semi-visible jets! The ATLAS Collaboration has come up with the first search for semi-visible jets, looking for them in a general production mode where two protons interact by exchanging an intermediate particle, which is then converted into two jets.

Physics Briefing | 26 May 2023

LHC experiments see first evidence for rare Higgs boson decay into two different bosons

The ATLAS and CMS Collaborations have joined forces to report first evidence of the Higgs boson decaying into a Z boson and a photon.

Physics Briefing | 26 May 2023

LHC experiments see first evidence of a rare Higgs boson decay

ATLAS and CMS teamed up to find the first evidence of the rare process in which the Higgs boson decays into a Z boson, the electrically neutral carrier of the weak force, and a photon, the carrier of the electromagnetic force.

Press Statement | 26 May 2023

New high-precision measurements of W and Z boson properties

At the 2023 LHCP conference, ATLAS physicists presented precise new measurements of the W± and Z boson transverse momentum distributions at two centre-of-mass energies: 13 TeV and, for the first time, 5.02 TeV. These results give unprecedented information on these transverse-momentum shape spectra, providing crucial input for other studies of these bosons.

Physics Briefing | 25 May 2023

ATLAS measures the Higgs boson at 13.6 TeV

The ATLAS Collaboration just released new measurements of the production rate (or cross-section) of Higgs bosons at 13.6 TeV using data collected in the second half of 2022.

Physics Briefing | 24 May 2023

Summary of new ATLAS results from LHCP 2023

The eleventh annual conference on Large Hadron Collider physics (LHCP 2023) kicks off today in Belgrade (Serbia) signaling the return of this week-long event to its face-to-face format. The programme of this edition covers the wide spectrum of Large Hadron Collider physics and technology, from several final studies of the LHC Run-2 dataset (2015-2018) to detailed assessments of the upgraded accelerators and detectors for Run 3.

News | 22 May 2023

ATLAS Live: Behind the Scenes at the Control Room

On 5 May at 4pm CEST, ATLAS physicists Dr. Stefanie Morgenstern and Dr. Liaoshan Shi will give a live tour of the ATLAS Control Room on the ATLAS and CERN Youtube Channels.

News | 04 May 2023