The ATLAS trigger system operated extremely successfully during Run 1 (2009–2013) and Run 2 (2015–2018) of the LHC. It is now undergoing various upgrades in preparation for the upcoming Run-3 data-taking period, which will see a moderate increase in the rate of collisions inside the experiment.

According to the Standard Model, most particles get their mass through an interaction with the Higgs field. If dark-matter particles acquire their mass in the same way, a Higgs boson created in an LHC collision might sometimes decay into a pair of “invisible” dark-matter particles. The ATLAS Collaboration has released a new search for invisible Higgs-boson decays using the full Run-2 dataset.

On 17 February 2022 at 8pm CET, Dr. Karolos Potamianos will give a live public talk on the ATLAS Youtube Channel on the study of the electroweak force and the role it plays in the Universe.

Physicists from the ATLAS Collaboration have combined two measurements of the interaction strength of the Higgs boson with two different pairs of quarks. This allows physicists to test a hypothesis that the Higgs boson interacts with charm quarks (which are second-generation quarks) in the same way it interacts with beauty quarks (third-generation quarks).

Former ATLAS engineer Elwyn Baynham shares his experience as part of the team developing the ATLAS End-Cap Toroids. His story paints a personal picture of the history of these incredible magnets.

The ATLAS Collaboration has completed the installation of “Phase-I” upgrades of the Liquid Argon Calorimeter (LAr). The upgrades improve the read-out speed of the calorimeter’s electronics and provide more efficient event-selection capabilities. These improvements will be pivotal for data-taking during the coming high-intensity runs of the LHC.

The ATLAS Collaboration has just released a new paper combining LHC and HERA data to determine Parton Distribution Functions (PDFs), which describe what fraction of a proton’s momentum is taken by its constituent quarks and gluons.

The ATLAS Collaboration has released updated measurements of the Higgs boson properties using the full LHC Run-2 dataset (recorded 2015-2018).

The 30th International Symposium on Lepton Photon Interactions at High Energies (Lepton Photon 2021) kicks off today. Explore the ATLAS results that will be presented.

When I received an email from the ATLAS outreach coordinators in October 2021, asking if I would help them make an ATLAS-inspired gingerbread village for this year’s card, I couldn’t refuse an opportunity for another fun “Physics Cakes” project.

Could there be another source of asymmetry in the Universe? ATLAS physicists are studying the differences between positively- and negatively-charged electrons and muons, looking for signs of charge–lepton-flavour symmetry breaking.

For several years, the ICTP Physics Without Frontiers (PWF) programme has been heavily involved with outreach activities to inspire, train and educate young and motivated physics students worldwide. Several members of the ATLAS Collaboration very active in this programme.

According to the Standard Model, the Higgs boson can interact with itself, resulting in the simultaneous production of two Higgs bosons ("di-Higgs production"). In a new result, the ATLAS Collaboration combines three di-Higgs decay channels to reach the best limits yet on di-Higgs production.

On 22 November 2021 at 8pm CET, Dr. Heather Russell will give a live public talk on the ATLAS Youtube Channel on the "trigger", the ATLAS event selection system.

4 November 2021, Geneva. The ATLAS Experiment at CERN welcomes a brand-new detector: the Muon New Small Wheel system. Its successful installation follows nearly a decade of design and construction, and marks a major milestone in ATLAS’ high-luminosity era.

Following several years of development, ATLAS Collaboration has launched a new "multithreaded" release of its analysis software, Athena.

The ATLAS Collaboration is breathing new life into its LHC Run-2 dataset, recorded from 2015 to 2018. Physicists will be reprocessing the entire dataset – nearly 18 PB of collision data – using an updated version of the ATLAS offline analysis software (Athena). Not only will this improve ATLAS physics measurements and searches, it will also position the Collaboration well for the upcoming challenges of Run 3 and beyond.

ATLAS physicists Florencia Daneri and Waleed Ahmed share the latest news from the Charge-Higgs@LHC workshop, which took place online August 30-31, 2021.

On 23 September 2021 at 8pm CEST, Dr. Maria Moreno Llácer will give a live public talk on the ATLAS Youtube Channel on the top quark. She will explain what makes this quark such a unique particle and describe the role it plays in the search for new physics.

Finding the differences between these types of matter – while extremely challenging – could reveal well-hidden effects that hint at the existence of new particles and interactions. In a new result presented at the TOP 2021 conference, the ATLAS Collaboration probed the heaviest-known elementary particle, the top quark, in search of these effects.

ATLAS’ vibrant physics programme was on full display at EPS-HEP 2021, with members presenting 26 new physics analyses among other key recent results. These were shown in 63 presentations and 45 posters over the five days.

In a new study, the ATLAS Collaboration looked for Z bosons decaying into an electron and an anti-muon, or into a muon and a positron.

The ATLAS Collaboration releases new measurements of the Higgs-boson decay to tau leptons. The result provides new insight into the “Yukawa coupling”, a key interaction of the Higgs boson.

One of the long-term goals of the LHC is to measure the Higgs-boson self-coupling, which in turn can give us clues about the formation of the early Universe. This self-coupling can only be measured directly by studying the production of pairs of Higgs bosons (HH).

The ATLAS Collaboration has released a new result searching for pairs of Higgs bosons (HH) produced by new particles. The Higgs bosons would then each decay into pairs of bottom (b) quarks – known as the '4b decay channel'.