Briefings

Hunting for magnetic monopoles with the Universe's strongest magnetic fields

In a new result from the ATLAS Collaboration, physicists analysed the first Run-3 heavy-ion collision data collected in the autumn of 2023. Specifically researchers looked at “ultraperipheral” collisions, where ions pass at a distance precluding hadronic interactions yet close enough to interact through electromagnetic fields.

Physics Briefing |

Jetting into a new era of Higgs studies

The ATLAS Collaboration has made a significant advancement in the understanding of the Higgs boson by investigating its production in association with W or Z bosons (known as “VH production”), where the Higgs boson decays to bottom quarks. For the first time, LHC researchers have studied VH production in a fully hadronic final state.

Physics Briefing |

ATLAS searches for the building blocks of dark matter

Researchers at the ATLAS Experiment release the first-ever direct search for new composite dark particles called dark mesons, presented this week at the Large Hadron Collider Physics (LHCP) Conference in Boston.

Physics Briefing |

ATLAS chases long-lived particles with the Higgs boson

In a new study submitted to Physical Review Letters, ATLAS scientists used a new algorithm to search for long-lived particles (LLP) produced in the decay of Higgs bosons. These LLPs may leave a distinct signature of one or more hadronic “jets” of particles originating at a significantly displaced position from the proton–proton collision point.

Physics Briefing |

Looking for the extended family of the Higgs boson

The ATLAS Collaboration has just published a search for two new Higgs bosons, X and S, that would interact with the Standard-Model Higgs boson.

Physics Briefing |

Menu of the day: Di-Higgs soup!

If spotting one Higgs boson is interesting, what happens when you spot two? ATLAS researchers are looking for the production of two Higgs bosons using a new technique.

Physics Briefing |

ATLAS explores Z boson production with heavy-flavour quarks

Using the full LHC Run-2 dataset, the ATLAS Collaboration measured Z boson production in association with both bottom (b) and charm (c) quarks, the latter for the first time in ATLAS.

Physics Briefing |

ATLAS detects electrons and photons with greater clarity

New results released by the ATLAS Collaboration describe the significant advancements made in identifying electrons and photons.

Physics Briefing |

ATLAS provides first measurement of the W-boson width at the LHC

In a groundbreaking new result, the ATLAS Collaboration has measured the W-boson width for the first time at the Large Hadron Collider (LHC).

Physics Briefing |

First ATLAS measurement of W and Z boson production using Run-3 data

The ATLAS Collaboration has just released its first measurements using LHC Run-3 data of the production rates (“cross sections”) of W and Z bosons.

Physics Briefing |

Measuring the delicate balance of lepton flavours

In a new result presented at Moriond EW, physicists at the ATLAS Collaboration tested lepton flavour universality between muons and electrons. The precision of the result stands as the best yet-achieved in W-boson decays by a single experiment and surpasses the world average.

Physics Briefing |

ATLAS searches for new particles in familiar decays

In a new result, researchers conducted a novel search of data collected during Run 2 of the LHC, searching for heavy new particles that could fit the 2HDM or 2HDM+S models.

Physics Briefing |

ATLAS measures rare Higgs boson interaction with tau leptons

In a new result, the ATLAS Collaboration reports the first evidence of a Higgs boson produced in association with a leptonically-decaying W or Z boson and decaying into a pair of tau leptons.

Physics Briefing |

Searching for supersymmetric needles in the LHC haystack

The ATLAS Collaboration has published three new results in this challenging area, using Boosted Decision Trees (BDTs) to isolate potential signals and ultimately set stringent constraints on the masses of SUSY particles.

Physics Briefing |

ATLAS gains momentum in study of charmonium

The ATLAS Collaboration has measured the production cross section of the J/ψ and ψ(2S) charmonium states in terms of the transverse momentum and the rapidity. For both states, they examined the widest range of transverse momentum so far, thus providing new input for theoretical models.

Physics Briefing |

ATLAS and CMS unite to weigh in on the top quark

The ATLAS and CMS Experiments at CERN have just released a new measurement of the mass of the top quark. The new result combines 15 previous measurements to give the most precise determination of the top-quark mass to date.

Physics Briefing |

ATLAS achieves highest-energy detection of quantum entanglement

In a new result from the ATLAS Collaboration, physicists observed – for the first time – quantum entanglement between a pair of quarks. This is the highest-energy measurement of entanglement to date.

Physics Briefing |

Shedding light on Higgs-boson self-interactions

The ATLAS Collaboration has released two brand-new results searching for di-Higgs events in the full LHC Run-2 dataset. In one, researchers looked for events where one Higgs boson decays into two bottom quarks and the other decays into two photons. In the other, they looked for events where one Higgs boson decays into two bottom quarks, and the other into two tau leptons or W/Z bosons, which subsequently decay into leptons.

Physics Briefing |

ATLAS observes top quarks in proton-lead collisions

The ATLAS Collaboration at CERN observes the production of top-quark pairs in proton-lead ion collisions. ATLAS’ new result confirms and builds upon an earlier observation made by the CMS Collaboration, expanding it into a new decay channel.

Physics Briefing |

When jets go dark

For the very first time, the ATLAS Collaboration has searched for dark jets that closely resemble QCD jets. Instead of originating from Standard-Model particles, these dark jets would be produced through a new, heavy particle called the Z' boson.

Physics Briefing |

ATLAS measures ZZ production using Run-3 data and a new slim data format

The ATLAS Collaboration has just released a new measurement of the production cross section of two Z bosons. This highlight result examines data collected during Run 3 of the LHC and pioneers the use of PHYSLITE, a new, reduced data format that requires significantly less storage.

Physics Briefing |

ATLAS searches for new phenomena using unsupervised machine learning for anomaly detection

In a new paper submitted to Phys. Rev. Lett., the ATLAS Collaboration pioneers the use of unsupervised machine learning to search for anomalous collision events which could be from new physics phenomena.

Physics Briefing |

Quest for the curious magnetic monopole continues

In a new study presented at the EPS-HEP 2023 conference, the ATLAS Collaboration combed through the full LHC Run-2 dataset (recorded 2015-2018) in search for magnetic monopoles and HECOs (see Figure 1). The result places some of the tightest limits yet on the production rate of magnetic monopoles.

Physics Briefing |

ATLAS releases comprehensive review of supersymmetric dark matter

In new results presented today, the ATLAS Collaboration provides its most comprehensive overview of the searches for weakly-interacting supersymmetric particles. By developing new search algorithms and exploiting machine learning techniques, researchers have probed deep into this difficult-to-reach territory.

Physics Briefing |

Three’s no crowd: ATLAS measures tri-boson production

The ATLAS Collaboration has announced the first observation of two different tri-boson processes: the simultaneous production of a W boson with two photons (Wγγ) and the production of a W boson, a Z boson and a photon (WZγ). The production of a Z boson with two photons (Zγγ) was first observed in 2016 using data from LHC Run 1 (2010-2013). In a new publication, the ATLAS Collaboration expanded the scope of this initial observation using Run 2 data.

Physics Briefing |