CERN Accelerating science

ATLAS

Higgs boson and the quest for new physics

The discovery of a new particle in 2012 by the ATLAS and CMS experiments at CERN was just the beginning in understanding the properties of this particle and its potential link to some of the most pressing fundamental questions in modern physics.…

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ATLAS New Small Wheel upgrade advances

Group photo after the installation of the last sector of NSW-A. On the right is NSW-C with the first three sectors installed at the time. The New Small Wheel (NSW) upgrade is an ambitious project that aims to allow, along with other upgrade projects…

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Mighty magnets for particle detectors

The ATLAS Magnet Team, part of the EP-ADO-SO section, has the principal responsibility for the maintenance and operation of the ATLAS Superconducting Magnets. This effort is supported by a large number of colleagues, in particular from EP-DT, TE-CRG…

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LHC takes on the SMEFT challenge

The quest for new physics at the LHC is entering a new phase: the experiments are designing new strategies to target potential deviations from the Standard Model (SM) predictions in a systematic way, to complement the traditional “bump hunts” and,…

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ATLAS faces the challenge of Run 3

The ATLAS experiment is a general-purpose particle detector operating at the LHC. It consists of several concentric layers of particle detectors occupying a cylindrical volume 46m long and 25m in diameter. The innermost detectors reconstruct the…

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The likelihood is dead, long live the likelihood

Among the sciences, particle physics has the luxury of having a well established theoretical basis. Often we focus on the elementary particles and model them mathematically with quantum field theories like the Standard Model. In order to compare…

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CERN's new open data policy supports open science

The four main LHC collaborations (ALICE, ATLAS, CMS and LHCb) have unanimously endorsed a new open data policy for scientific experiments at the Large Hadron Collider (LHC), which was presented to the CERN Council today. The policy commits to…

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Stephanie Zimmermann (1973 – 2020)

  We have been deeply saddened to hear about the passing of Stephanie Zimmermann, an outstanding physicist, who has made a long-lasting contributions to the ATLAS experiment. Stephanie was involved in the Muon Detector Control System activities and…

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Machine learning ushers in a new paradigm for particle searches at the LHC

Searching for physics beyond the Standard Model (BSM) is a major part of the research programme at the LHC experiments. Nearly all of these searches pick a signal model that addresses one or more of the experimental (e.g., dark matter) or…

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What is the likelihood function, and how is it used in particle physics?

In statistical data analysis, “likelihood” is a key concept that is closely related to, but crucially distinct from, the concept of “probability”, which is often a synonym in everyday English. In this article, I first lay some necessary foundations…

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