Angular observables sensitive to the spin and parity of a Higgs boson decay.

The scalar boson

26th March 2015The ATLAS experiment has released results confirming that the Higgs boson has spin 0 (it is a so-called “scalar”) and positive parity as predicted by the Standard Model, making it the only elementary scalar particle to be observed in nature.

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Candidate event in the search for a Higgs boson produced together with a top-antitop quark pair.

In search of rare Higgs boson production with top quarks

24th March 2015In proton-proton collisions, several processes can lead to the production of a Higgs boson. The most “frequent” process (which is about one collision in four billion!) is the fusion of two gluons, contained in the initial protons, into a Higgs boson through a “top-quark loop”. Least frequent is a mode where the Higgs boson is produced in association with a pair of top-quarks.

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Latest ATLAS results on the Higgs Boson

19th March 2015 – On 17 March, ATLAS presented their latest Higgs physics results at an LHC seminar at CERN from data collected during the LHC's first run. The updated results include searches for the Higgs boson in association with top quarks, measurements of the spin and parity, and improved and combined coupling measurements, all showing good compatibility with Standard Model predictions. These results are also being presented at the 50th Rencontres de Moriond ElectroWeak conference, in La Thuile, Italy, this week.

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ATLAS physicist wins L'Oreal-UNESCO Women in Science award

12th March 2015 – Rajaâ Cherkaoui El Moursli is one of the five laureates of the L'Oreal-UNESCO for Women in Science Awards this year.

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ATLAS' Higgs ML Challenge data open to public

5th March 2015 – The dataset from the ATLAS Higgs Machine Learning Challenge has been released on the CERN Open Data Portal.

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Winners of the ATLAS Thesis Awards announced

27th February 2015 – Six PhD students were announced as the winners of the ATLAS Thesis Awards 2014 from 28 nominations received. The winners – Andrew Chisholm, Kun Liu, Marcus Morgenstern, Priscilla Pani, Dennis Perepelitsa, and James Saxon – were given certificates and an engraved glass model of the ATLAS detector during a ceremony on 19 February 2015 at CERN, Geneva.

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Second ATLAS PhD Grants

23rd February 2015 – The recipients of the second ATLAS PhD Grant were announced last week. The three young ATLAS physicists – Danijela Bogavac, Silvia Fracchia, and Declan Millar – were given certificates at a small ceremony at CERN, Geneva.

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Looking at the Dark side of Matter

19th February 2015The search continues for dark matter, a new kind of matter that doesn’t emit or absorb light. It is assumed to account for the missing amount of mass in our Universe. The total mass in our Universe can be inferred from the observation of gravitational effects of stars in galaxies, and galaxies in clusters of galaxies. However the amount of mass calculated from the observed distribution of light is much less. It is proposed that dark matter makes up the discrepancy as it does not emit light.

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Cleaning ATLAS cables

The Ties That Bind

15th January 2015A few weeks ago, I found myself in one of the most beautiful places on earth: wedged between a metallic cable tray and a row of dusty cooling pipes at the bottom of Sector 13 of the ATLAS Detector at CERN. My wrists were scratched from hard plastic cable ties, I had an industrial vacuum strapped to my back, and my only light came from a battery powered LED fastened to the front of my helmet. It was beautiful.

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ATLAS collision event with two charm-tagged jets.

In search of super charm

9th January 2015 – If all the experimental evidence supports a theory, why should anyone want to dream up additional particles? Yet exactly this situation arose in the late 1960s. At that time, when the complete table of the known hadrons could be explained with just three quarks, theorists were already proposing a fourth, which they whimsically called “charm”.

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