Updates tagged: “EXOT group”
Many theoretical models predict that new physics, which could provide answers to these questions, could manifest itself as yet-undiscovered massive particles. These include massive new particles that would decay to much lighter high-momentum electroweak bosons (W and Z). These in turn decay, and the most common signature would be pairs of highly collimated bundles of particles, known as jets.
The ATLAS collaboration is continuing to scour the wealth of data provided by the LHC for any signs of physics beyond the particles and interactions described by the Standard Model. One approach is to search for new forces in addition to the Standard Model’s electroweak and strong interactions. Such forces could be propagated by new massive bosons playing the role the W and Z bosons have in mediating the electroweak force.
What do you do when you produce more data than you can handle? This might seem like a strange question for experimental physicists, but it’s a problem that the ATLAS detector faces every day. While the LHC continues to produce ever-higher rates of proton collisions, the detector can only record data at a fixed rate. Therefore, tough choices must be made about what events to keep. This is not a decision made lightly – what if the thrown-away data contain some long-sought new particles beyond those of the Standard Model.
As the Large Hadron Collider (LHC) smashes together protons at a centre-of-mass energy of 13 TeV, it creates a rich assortment of particles that are identified through the signature of their interactions with the ATLAS detector. But what if there are particles being produced that travel through ATLAS without interacting? These “invisible particles” may provide the answers to some of the greatest mysteries in physics.
Although the discovery of the Higgs boson by the ATLAS and CMS Collaborations in 2012 completed the Standard Model, many mysteries remain unexplained. For instance, why is the mass of the Higgs boson so much lighter than one would expect and why is gravity so weak?
Cosmological and astrophysical observations based on gravitational interactions indicate that the matter described by the Standard Model of particle physics constitutes only a small fraction of the entire known Universe. These observations infer the existence of Dark Matter, which, if of particle nature, would have to be beyond the Standard Model.
The fundamental forces of nature are intimately related to corresponding symmetries. For example, the properties of electromagnetic interactions (or force) can be derived by requiring the theory that describes it to remain unchanged (or invariant) under a certain localised transformation. Such an invariance is referred to as a symmetry, just as one would refer to an object as being symmetric if it looks the same after being rotated or reflected. The particular symmetry related to the forces acting among particles is called gauge symmetry.
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.
One of the highlights of last year’s physics results was the appearance of an excess in the search for a new particle decaying into two photons ("the di-photon channel"). New results in this channel were presented at the ICHEP conference in Chicago on Friday, 5 August.
For a long time, physicists have assumed that space-time has four dimensions in total – three of space and one of time – in agreement with what we see when we look around us. However, some theorists have proposed that there may be other spatial dimensions that we don’t experience in our daily lives.