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.

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'.

The ATLAS Collaboration announces the first observation of “WWW production”: the simultaneous creation of three massive W bosons in high-energy LHC collisions.

What can particles of light – photons – tell us about the inner workings of the Standard Model? A new paper from the ATLAS Collaboration measures pairs of photons to improve the understanding of a fundamental force of Nature – the strong force – and thus scrutinise the theoretical models that underpin high-energy physics research. 

A new result from the ATLAS Collaboration studies the interactions of photons – particles of light – with lead nuclei at the Large Hadron Collider (LHC). Using new data collection techniques, physicists revealed an unexpected similarity to the experimental signatures of the quark–gluon plasma.

The ATLAS Collaboration has released three new searches for "higgsinos" - the super-partner of the Higgs boson.

A new search from the ATLAS Collaboration, released this week at the Large Hadron Collider Physics conference (LHCP 2021), sets limits on the mass of the W’ boson.

In a new result presented by the ATLAS Collaboration, physicists have measured – for the first time – the full polarisation vectors for both top quarks and antiquarks. 

At the LHCP2021 conference, the ATLAS Collaboration presents a new direct search for the decay of the Higgs boson to charm quarks. Observing this decay would give physicists new insight into the Higgs boson’s relationship with the second generation of matter particles.

In the post-Higgs discovery era, scientists at the Large Hadron Collider (LHC) have been hard at work studying the Higgs boson’s properties. One property that remains to be experimentally verified is whether the Higgs boson can couple to itself (self-coupling).

In a new result released this week, the ATLAS Collaboration studied the production of four top quarks at once in LHC collisions. This is the heaviest particle final state ever seen at the LHC, and provides physicists with a unique opportunity to study the top quark’s relationship to the Higgs boson.

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.

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.

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. 

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.

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

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.

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.

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

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?

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.

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