JETM group

More than the sum of its parts: inside the proton

Discovered almost 100 years ago by Ernest Rutherford, the proton was one of the first particles to be studied in depth. Yet there’s still much about it that remains a mystery. Where does its mass and spin come from? What is it made of? To answer these questions, ATLAS physicists are using “jets” of particles emitted by the LHC as a magnifying glass to examine the inner structure of the proton.

13th June 2017

Making the most of the ATLAS detector

Up to now, ATLAS has measured the energies and positions of jets using the finely segmented calorimeter system, in which both electrically charged and neutral particles interact. However, the inner detector tracking system provides more precise measurements of charged particle energies and positions. A recent ATLAS paper describes a particle flow algorithm that extrapolates the charged tracks seen by the inner detector to the calorimeter regions.

2nd May 2017

What happens when energy goes missing?

Here at ATLAS, we like to consider ourselves pretty decent at tracking down particles. In fact, we do it every day. Just because a proton-proton collision doesn’t produce the next Nobel Prize winning particle doesn’t mean we can ignore it. Teams of physicists are still combing through every single event, rebuilding known particles out of the signals they leave us

3rd November 2016

Precision measurements with multi-TeV energy jets

The strong force is one of the four fundamental interactions of Nature. It governs the interactions between quarks and gluons, and is thus responsible for the stability of ordinary matter. In the proton-proton collisions at the Large Hadron Collider, the strong force is seen in the production of collimated sprays of mesons and baryons, known as hadron jets. The ATLAS Collaboration has released the measurement of the inclusive jet production cross sections at the new 13 TeV energy frontier.

23rd August 2016

Hunting for new physics with boosted bosons

The Standard Model is a tremendously successful theory that describes our best understanding of elementary particles and their interactions, and even predicted the existence of the Higgs Boson. It does not however explain ~95% of the known universe – including dark matter and dDark energy – and does not include a description of gravity.

6th August 2016

Searching for new phenomena in final states with missing momentum and jets

The nature of dark matter remains one of the greatest mysteries in physics. While extraordinary, the Standard Model can not explain dark matter, whose existence is well established by cosmological measurements.

4th August 2016

A boost for the next discovery

I arrived in Chicago for my first conference after the first long LHC shutdown, where new results from the two big experiments ATLAS and CMS were to be shown. Before the beginning of the conference on Monday, I had one day to fight against jetlag and see the city – certainly not enough time to see everything!

14th August 2015

Boost and never look back

When I arrived in Chicago this last Sunday for the BOOST conference I had a pretty good idea what new results we were going to show from ATLAS. I also had some rough ideas of what our friends from the other experiments and theory groups would be up to. What I didn’t expect was to see an ad that would fit the conference so nicely!

12th August 2015

ATLAS ready to “boost” Run 2 physics

A new set of techniques is being used to identify highly energetic top quarks, W and Z bosons, and Higgs bosons decaying to quarks and, ultimately, to hadrons measured in ATLAS. Signatures of these “boosted” Standard Model particles are particularly useful when searching for massive new particles and measuring processes at high energies.

12th August 2015

First measurements set the stage for early searches of new physics

Jets are collimated sprays of hadrons generated from quarks and gluons, produced either directly in the proton-proton collision or as a part of the decay of W bosons, Z bosons, Higgs bosons, top quarks or new particles yet to be discovered. In fact, all W, Z and Higgs bosons decay most often to quarks which form jets.

24th July 2015

Run 1 search for new massive bosons builds excitement for Run 2

The ATLAS experiment is now taking data from 13 TeV proton-proton collisions. The increased collision energy and rate in these Run 2 collisions will allow physicists to carry out stronger tests of many theoretical conjectures, including several theories that predict more massive versions of force-carrying particles like the W and Z bosons.

19th June 2015

Looking at the Dark side of Matter

The 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.

19th February 2015

Are quarks fundamental particles?

From decades of discoveries made at particle colliders, we know that protons are composed of quarks bound together by gluons. We also know that there are six kinds of quarks, each one with its associated antiparticle. But are quarks fundamental? ATLAS searched for signs that quarks may have substructure in its most recent data, collected from the LHC’s proton-proton collisions in 2012.

6th July 2014

Hunting for the top squark

Completion of the analysis of 2012 data recorded by the ATLAS detector at the LHC’s collision energy of 8 TeV has significantly improved our capability of finding a supersymmetric partner of the top quark – also known as the top squark or the stop.

5th July 2014

The production of W bosons in association with jets

The production of a W boson in association with “jets” of particles initiated by quarks or gluons (“W+jets” events) is an important signature to test quantum chromodynamics, the theory of strong interactions. A new measurement reported by ATLAS focuses on studying the properties of the jets in a large data sample of W+jets events.

5th July 2014

A Search for New Physics Processes using Dijet Events

The ATLAS Experiment has extended the energy frontier of searches for new particles and new processes beyond those of the Standard Model by studying collision events with so-called "dijets".

21st June 2011