5th September 2018 – The Brout-Englert-Higgs (BEH) mechanism is at the core of the Standard Model, the theory that describes the fundamental constituents of matter and their interactions. It introduces a new field, the Higgs field, through which the weak bosons (W and Z) become massive while the photon remains massless. The excitation of this field is a physical particle, the Higgs boson, which was discovered by the ATLAS and CMS collaborations in 2012.
28th August 2018 – The ATLAS Collaboration at CERN’s Large Hadron Collider (LHC) has – at long last – observed the Higgs boson decaying into a pair of bottom (b) quarks. This elusive interaction is predicted to make up almost 60% of the Higgs boson decays and is thus primarily responsible for the Higgs natural width. Yet it took over six years after the 2012 discovery of the Higgs boson to accomplish this observation.
14th August 2018 – While the Standard Model has proven tremendously successful, much experimental evidence points to it not being a complete description of our universe. The search for “new physics” is therefore an important component of the ATLAS experimental programme, where a number of analyses are looking for signs of new heavy particles decaying to different final states. Though these searches have not yet found a significant signal, they have allowed physicists to place stringent constraints on different new physics scenarios. These can be further tightened by combining different analysis channels and approaches.
10th August 2018 – “Multiculturalism” isn’t just a buzzword for ATLAS, it’s a way of life. With members of over 90 different nationalities – spanning every populated continent – ATLAS is a cultural experiment as much as it is a scientific one. Our new ATLAS Around the World series invites you to meet people from every nationality represented in the collaboration, to gain an insight into the individual journeys that brought them to particle physics. All are from very different backgrounds, but share the common goal of understanding our universe.
8th August 2018 – While the discovery of the Higgs boson at the Large Hadron Collider (LHC) in 2012 confirmed many Standard Model predictions, it has raised as many questions as it has answered. For example, interactions at the quantum level between the Higgs boson and the top quark ought to lead to a huge Higgs boson mass, possibly as large as the Planck mass (>1018 GeV). So why is it only 125 GeV? Is there a mechanism at play to cancel these large quantum corrections caused by the top quark (t)? Finding a way to explain the lightness of the Higgs boson is one of the top (no pun intended) questions in particle physics.
26th July 2018 – Since the beginning of ATLAS, collaboration members have devoted hours, days, weeks and months teaching High Energy Physics (HEP) to anyone willing to listen. But sometimes those willing to listen do not have the means, especially when oceans and continents separate them from our experiment in Geneva. How can we overcome these geographical distances to allow anyone interested in HEP to learn?
17th July 2018 – Feynman. Salam. Weinberg. For the past 50 years, the International Conference on HighEnergy Physics (ICHEP) has been the meeting place of giants in the field. Now, a new type of giant dominates: the thousands-strong collaborations of Large Hadron Collider (LHC) physicists.
10th July 2018 – What a start it's been to my first conference! I was lucky enough to join the 39th International Conference on High Energy Physics (ICHEP), the biggest conference in High Energy Physics. About 1000 physicists are currently gathered in Seoul, presenting results from all across the field. Getting to visit South Korea plus hearing about cutting-edge physics sounded like a 5-star recipe to me!
9th July 2018 – Today, at the 2018 International Conference on High Energy Physics in Seoul, the ATLAS experiment reported a preliminary result establishing the observation of the Higgs boson decaying into pairs of b quarks, furthermore at a rate consistent with the Standard Model prediction.
9th July 2018 – Higgs boson couplings manifest themselves in the rate of production of the Higgs boson at the LHC, and its decay branching ratios into various final states. These rates have been precisely measured by the ATLAS experiment, using up to 80 fb–1 of data collected at a proton-proton collision energy of 13 TeV from 2015 to 2017. Measurements were performed in all of the main decay channels of the Higgs boson: to pairs of photons, W and Z bosons, bottom quarks, taus, and muons. The overall production rate of the Higgs boson was measured to be in agreement with Standard Model predictions, with an uncertainty of 8%. The uncertainty is reduced from 11% in the previous combined measurements released last year.