Better late than never: ATLAS searches for late-decaying new particles

A new result from the ATLAS Collaboration – debuted at the virtual Moriond Electroweak conference – sets itself apart from more traditional LHC searches. Typically, physicists will look for new particles produced in LHC collisions that immediately decay to known or invisible particles. This analysis, in contrast, looks for new particles that live for roughly a hundred nanoseconds or more before decaying.

Physics Briefing | 23 Mar 2021

Deeper insight into Higgs boson production using W bosons

The Higgs boson reveals its properties to the outside world twice: during production and decay. ATLAS’ new result studies the Higgs boson at both of these moments, looking at its production via two different methods and its subsequent decay into two W bosons.

Physics Briefing | 22 Mar 2021

Summary of new ATLAS results from Moriond

Since 1966, Les Rencontres de Moriond has united experimentalists and theorists for weeks of scientific discussion. 2021 is no exception – but instead of in-person chats over coffee in La Thuile (Italy), physicists will be sharing their new findings in online meetings.

News | 21 Mar 2021

The supersymmetric bottom quark and its friends

The special status of the top and bottom quarks makes them key players in the search for phenomena not foreseen by the Standard Model. New ATLAS results set strong constraints on the production of supersymmetric bottom quarks and of possible dark-matter particles. 

Physics Briefing | 16 Mar 2021

Studying top quarks at high and not-so-high energies

CERN’s Large Hadron Collider (LHC) is famous for colliding protons at world-record energies – but sometimes it pays to dial down the energy and see what happens under less extreme conditions.

Physics Briefing | 11 Mar 2021

The power of position: aligning the ATLAS muon spectrometer

In new results released this week, ATLAS physicists describe novel techniques used to accurately align the muon spectrometer.

Experiment Briefing | 04 Mar 2021

ATLAS: now under new management

The ATLAS Collaboration welcomes new management this month, with Andreas Hoecker (CERN) taking the lead as Spokesperson for the experiment.

News | 02 Mar 2021

Planning an event during a pandemic

At the ATLAS Early Career Scientist Board (ECSB), we have also had to adapt in order to best represent and assist the early career scientists in our collaboration. One of the biggest changes was moving all of our events in the second half of 2020 to be entirely virtual.

Blog | 19 Feb 2021

Students step into the limelight: ATLAS awards excellent PhD theses

ATLAS PhD students are a key cohort of the Collaboration, making unique and crucial contributions to the experiment while working on their degree. Every year, their work is celebrated in the context of the ATLAS Thesis Awards.

News | 17 Feb 2021

ATLAS recognises the outstanding achievements of Collaboration members

The 2020 ATLAS Outstanding Achievement Awards ceremony was held online on 11 February 2021. Established in 2014, the awards recognise outstanding contributions in support of the ATLAS experiment, covering all areas except physics analysis. 

News | 16 Feb 2021

ATLAS finds evidence of a rare Higgs boson Dalitz decay to two leptons and a photon

ATLAS finds first evidence of the Higgs boson decaying to two leptons and a photon. This is one of the rarest Higgs boson decays yet seen at the LHC, with striking features that presented unique challenges for the ATLAS experiment.

Physics Briefing | 02 Feb 2021

Teaching university students with real ATLAS data

ATLAS PhD student Meirin Oan Evans explores how the University of Sussex is incorporating ATLAS Open Data into their teaching – and shares his experience using this incredible resource.

Blog | 27 Jan 2021

2020: an unprecedented year in review

Despite the huge challenges of the COVID-19 pandemic, last year saw excellent successes for the ATLAS Collaboration, including first-of-a-kind physics results and great headway made on detector upgrades.

News | 06 Jan 2021

Studying the Higgs boson in its most common – yet uncommonly challenging – decay channel

New results from the ATLAS Collaboration focus on different production modes of the Higgs boson decaying into b-quarks, capitalising on the power of machine learning to better discriminate this particular process from other proton collision events.

Physics Briefing | 01 Dec 2020

ATLAS releases new open software

The ATLAS Collaboration has just released a collection of 200 software packages that make up the Trigger and Data Acquisition System (TDAQ). With this new release, most ATLAS software is now open – reinforcing the Collaboration’s ongoing commitment to open science.

News | 20 Nov 2020

Refining the picture of the Higgs boson

A new result from the ATLAS Collaboration, released for the Higgs 2020 conference, aims at enriching the Higgs picture by studying its WW* decays.

Physics Briefing | 19 Nov 2020

ATLAS uses the Higgs boson as a tool to search for Dark Matter

One of the great unexplained mysteries is the nature of dark matter. So far, its existence has only been established through gravitational effects observed in space; no dark-matter particles with the needed properties have (yet) been detected. Could the Higgs boson be the key to their discovery?

Physics Briefing | 29 Oct 2020

Higgs boson probes for new phenomena

ATLAS scientists are implementing a new strategy in the search for physics beyond the Standard Model – one that combines measurements across the full spectrum of the Collaboration's research programme.

Physics Briefing | 28 Oct 2020

Leptons at a distance: a new search for long-lived particles

ATLAS researchers are broadening their extensive search programme to look for more unusual signatures of unknown physics, such as long-lived particles. A theory that naturally motivates long-lived particles is supersymmetry (SUSY). A new search from the ATLAS Collaboration – released this week for the 5th International Conference on Particle Physics and Astrophysics (ICPPA-2020) – looks for the superpartners of the electron, muon and tau lepton

Physics Briefing | 07 Oct 2020

Unraveling Nature's secrets: vector boson scattering at the LHC

In 2017, the ATLAS and CMS Collaborations announced the detection of a never-before-observed process: vector boson scattering.

Feature | 22 Sep 2020

Exploring the “coolest” mock-up

It was in 2014, just a few months after my transition from ALICE to ATLAS, that I saw the mock-up for the first time: a full-scale wooden reproduction of the central portion of the ATLAS experiment, measuring some 8 metres high and wide.

Blog | 10 Sep 2020

Z bosons zoom through quark–gluon plasma as jets quench

With new data from the LHC, ATLAS physicists have measured jet-quenching phenomena in the quark–gluon plasma with help of Z bosons.

Physics Briefing | 25 Aug 2020

ATLAS highlights presented at the world's largest particle-physics conference

As major players in the field of particle physics, the LHC collaborations contributed many new results, most of which exploited the full Run 2 dataset, recorded in 2015 to 2018. ATLAS physicists contributed 35 new results, and gave 85 talks in the parallel and plenary sessions. Their contributions spanned a wide range of topics, from precision measurements and searches for new phenomena to detector performance and R&D, as well as diversity and outreach.

News | 08 Aug 2020

Rare phenomenon observed by ATLAS features the LHC as a high-energy photon collider

During the International Conference on High-Energy Physics (ICHEP 2020), the ATLAS Collaboration presented the first observation of photon collisions producing pairs of W bosons, elementary particles that carry the weak force, one of the four fundamental forces. The result demonstrates a new way of using the LHC, namely as a high-energy photon collider directly probing electroweak interactions. It confirms one of the main predictions of electroweak theory – that force carriers can interact with themselves – and provides new ways to probe it.

Press Statement | 05 Aug 2020

ATLAS observes W-boson pair production from light colliding with light

The ATLAS Collaboration has announced the first observation of two W bosons produced from the scattering of two photons — particles of light – at the International Conference on High-Energy Physics (ICHEP 2020).

Physics Briefing | 05 Aug 2020