ATLAS & CMS Physicists Recover Lost Higgs Boson

Scientists working on the Large Hadron Collider at CERN breathed a sigh of relief today, as the world-renowned Higgs boson returned to its showcase in the heart of the laboratory.

Blog | 01 Apr 2023

Probing fundamental symmetries of nature with the Higgs boson

In the new results presented at the Moriond conferences, the ATLAS Collaboration tested the CP invariance of Higgs-boson interactions with vector bosons (W or Z bosons).

Physics Briefing | 31 Mar 2023

LHC passes a new milestone

The ATLAS Collaboration has just published the most precise measurement to date of the production cross section of top-quark pairs. The measured value is 829 ± 15 picobarns and has a relative uncertainty of just 1.8%.

Physics Briefing | 24 Mar 2023

ATLAS confirms mild tension in production of top-quark pairs with a W boson

The ATLAS Collaboration has released the most detailed analysis to date of the production of top-quark pairs alongside a W boson.

Physics Briefing | 24 Mar 2023

ATLAS observes the simultaneous production of four top quarks

The ATLAS Collaboration at CERN announces the observation of the simultaneous production of four top quarks. This is one of the rarest – and heaviest – processes ever observed at the Large Hadron Collider (LHC), with a total particle mass of almost 700 GeV.

Physics Briefing | 24 Mar 2023

ATLAS measures the strength of the strong force

The ATLAS Collaboration at CERN has released a precise new measurement of the Z-boson transverse momentum. This has allowed researchers to determine the strength of the strong force. Their result has less than 1% uncertainty, making it the most precise determination of the strong force ever made by a single experiment.

Physics Briefing | 23 Mar 2023

New ATLAS result weighs in on the W boson

The ATLAS Collaboration has measured the W boson mass to be 80360 MeV with an uncertainty of 16 MeV – in agreement with the Standard Model.

Physics Briefing | 23 Mar 2023

Searching from top to bottom for lepton unity

The ATLAS Collaboration has released an impressive set of searches for leptoquarks interacting with third-generation leptons or quarks – placing valuable constraints on leptoquark parameters.

Physics Briefing | 22 Mar 2023

Tau & co.: the search for new physics with the heaviest leptons

The ATLAS Collaboration has released two new studies of the tau lepton, investigating whether this elementary particle may actually be composite in nature.

Physics Briefing | 21 Mar 2023

Summary of new ATLAS results from 2023 Winter Conferences

The winter conference season has begun! This month, all roads lead to La Thuile in the Italian Alps, where experimental physicists and theorists will take part in some of the most important particle physics meetings of the year. The La Thuile and Rencontres de Moriond conferences promise not to disappoint, with topical sessions ranging from heavy-ion and neutrino physics, to dark matter searches and astroparticle observations.

News | 16 Mar 2023

In conversation with Kevin Einsweiler, an instrumental voice in ATLAS upgrades

Kevin Einsweiler is a senior scientist at Lawrence Berkeley National Lab (LBNL). He joined the ATLAS Collaboration in 1993, playing an instrumental role in bringing US institutes into the LHC programme. He served as ATLAS Pixel Project Leader (2005-2009), Physics Coordinator (2011-2013) and Upgrade Coordinator (2014-2019).

Portrait | 06 Mar 2023

ATLAS management begins new term

The ATLAS Collaboration at CERN welcomes a new management team at its helm. Spokesperson Andreas Hoecker (CERN) will continue to steer the experiment until March 2025.

News | 06 Mar 2023

Winners of the 2022 ATLAS Thesis Awards announced

Behind nearly every great ATLAS result lies an outstanding PhD student! Students are a key cohort of the ATLAS Collaboration, making critical contributions to the experiment while working on their degree. Every year, the Collaboration comes together to celebrate their work in the context of the ATLAS Thesis Awards.

News | 20 Feb 2023

ATLAS delivers most precise luminosity measurement at LHC

The ATLAS Collaboration has just released its most precise luminosity measurement to date. They studied four years of measurements (2015-2018), covering the entire Run 2 of the LHC to assess the amount of luminosity delivered to the ATLAS experiment.

Experiment Briefing | 24 Jan 2023

A new ATLAS for the high-luminosity era

Stefan Guindon, Christian Ohm and Caterina Vernieri describe the major ‘Phase II’ upgrades taking place to prepare the ATLAS detector for the High-Luminosity LHC.

Feature | 18 Jan 2023

ATLAS casts wide net in search for new high-mass particles

The ATLAS Collaboration has performed an extensive search for new, high-mass particles that can decay to a pair of W bosons. As many theoretical models predict the existence of such high-mass particles, physicists were able to investigate the validity of several models at once across a large energy range.

Physics Briefing | 01 Dec 2022

ATLAS moves into top gear for Run 3

The ATLAS Collaboration has just released its first Run 3 measurements, studying data collected in the first half of August 2022. Researchers have measured the interaction strength (or cross-section) of two well-known processes: the production of a pair of top quarks and the production of a Z boson.

Physics Briefing | 30 Nov 2022

ATLAS measures Higgs width

In a highlight result presented at the Higgs 2022 conference, the ATLAS Collaboration studied the production of off-shell Higgs bosons with a high invariant mass decaying into two on-shell Z bosons using the data collected during LHC Run 2 (2015-2018). For their new search, ATLAS physicists focused on events where the two Z bosons decay into four charged leptons (ZZ→4l channel) or two charged leptons plus two neutrinos (ZZ→ 2l2v channel), as they offered the highest signal sensitivity.

Physics Briefing | 15 Nov 2022

ATLAS and Seal Storage Technology collaborate on new archival storage

The ATLAS Collaboration has partnered with Seal Storage Technology in a pilot project to explore their decentralised cloud storage platform as an efficient and cost-effective option for archival data storage

News | 28 Oct 2022

ATLAS celebrates 30 years of collaboration

The ATLAS Collaboration celebrated its 30th anniversary on 1 October 2022.

News | 01 Oct 2022

ATLAS Live talk: Searching for new, long-lived particles at the LHC with Dr. Hideyuki Oide

On 6 October at 2pm CET, Dr. Hideyuki Oide will give a live public talk on the ATLAS Youtube Channel on the LHC's search for new, long-lived particles.

News | 27 Sep 2022

Using the Higgs boson to search for dark photons

The ATLAS Collaboration has been looking for signs of dark photons in data collected by the experiment during LHC Run 2 (2015-2018). Their newest search targets, for the first time in ATLAS, the production of a Higgs boson in association with a Z boson, with subsequent decay of the Higgs into a photon and a dark photon.

Physics Briefing | 15 Sep 2022

ATLAS Highlights from ICHEP 2022

At ICHEP 2022, the ATLAS Collaboration presented the results of 30 new studies, spanning from Higgs boson and Standard Model measurements to searches for new phenomena.

News | 22 Jul 2022

ATLAS observes potential four-charm tetraquark

In a new analysis presented at the ICHEP 2022 conference, ATLAS physicists found evidence of a four-charm-quark excess. Like the LHCb Collaboration, ATLAS sees both the X(6900) particle and a broad structure at threshold.

Physics Briefing | 09 Jul 2022

ATLAS measures quantum interference when protons bounce off each other

In a new result presented at ICHEP 2022, ATLAS physicists set out to measure proton scattering at microradian angles and study this quantum interference.

Physics Briefing | 08 Jul 2022