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 March 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%.
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.
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.
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 March 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 March 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 March 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 March 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 January 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 | 1 December 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 November 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 November 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 September 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 | 9 July 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 | 8 July 2022
ATLAS measures joint polarisation of W and Z bosons
In a new result presented at the ICHEP 2022 conference, ATLAS physicists have been able to observe events with both a W and Z boson simultaneously polarised longitudinally for the very first time.
Physics Briefing | 7 July 2022
ATLAS explores the self-interaction of the Higgs boson
In the most recent effort to constrain the Higgs self-coupling constant, ATLAS physicists used the full Run 2 dataset (collected during 2015-2018) to perform a combined study on the production of a single Higgs boson and two Higgs bosons. This single-Higgs analysis was featured in a paper released in Nature today, looking back on 10 years of Higgs boson research at the ATLAS Experiment
Physics Briefing | 4 July 2022
ATLAS Pixel detector in Run 3
The ATLAS experiment at the Large Hadron Collider (LHC) is on the eve of a new data harvest with the restart of the LHC for Run 3. The upcoming four-year run will provide a dataset nearly twice the size of what was collected in Run 2 (2015–2018).
Physics Briefing | 1 July 2022
Harnessing a supercomputer for ATLAS
ATLAS researchers are exploring the potential of High Performance Computing (HPC). HPC harnesses the power of purpose-built supercomputers constructed from specialised hardware, and is used widely in other scientific disciplines.
Experiment Briefing | 2 June 2022
ATLAS measures symmetry of Higgs boson decays to tau leptons
The ATLAS Collaboration has just released a new measurement of the CP properties of H→ττ interactions. The study of H→ττ allows researchers to understand the CP-nature of Higgs boson interactions.
Physics Briefing | 20 May 2022
The ATLAS Collaboration has released a new combined search for heavy vector bosons, which includes 13 individual searches studying different final states. The new combination includes, for the first time, a dedicated search for heavy particles decaying to third-generation leptons (taus).
Physics Briefing | 18 May 2022
ATLAS looks for top quarks going against the current
Using the full Run-2 dataset, the ATLAS Collaboration has published four analyses searching for flavour-changing neutral currents in the production and decay of the top quark. The results study top-quark processes involving all four neutral bosons: the photon, gluon, Z boson and Higgs boson.
Physics Briefing | 16 May 2022
Mass matters – but it isn't the only thing!
The ATLAS Collaboration finds evidence of parton mass, colour-charge and radiation-pattern dependence in quark-gluon-plasma induced energy loss.
Physics Briefing | 27 April 2022
ATLAS gives new insight into dijet suppression in heavy-ion collisions
At the recent Quark Matter 2022 conference in Krakow, Poland, members of the ATLAS Collaboration presented a new study of “jets” of particles travelling through the QGP. The result provides new insight into dijet suppression due to interactions with the nuclear medium.
Physics Briefing | 22 April 2022
ATLAS observes pairs of tau particles in heavy-ion collisions
Today at the Quark Matter 2022 Conference, the ATLAS Collaboration announced the observation of tau-lepton pairs created when particles of light – or photons – interact during lead-ion collisions. The result opens a new avenue for measuring how magnetic the tau lepton is – a property sensitive to new particles beyond the Standard Model.
Physics Briefing | 7 April 2022