How I Met Your Mother: UAlberta scientists help find the mother of everything, the Higgs boson

The Higgs boson helps scientists answer the burning question, ?who is our mother??

18 March 2013

(Edmonton) The discovery of the Higgs boson has been called the discovery of the century, and this week scientists came even closer to confirming its existence. This elusive particle has been the focus of an unprecedented international scientific quest to understand where we come from-to be able to answer the burning question, 'who is our mother?'

"The Higgs boson is a fundamental piece of the DNA of the universe. Its discovery is the first giant step in answering the profound question: how is there something rather than nothing," notes Dr. James Pinfold, one of the University of Alberta scientists who has made this discovery possible.

UAlberta physicists have played a key role in this discovery by providing their deep scientific expertise in the creation and evolution of the ATLAS collider at CERN. With 3,000 scientists from more than 30 countries offering contributions to the cause, the search for the Higgs comprises one the most intensely international scientific collaboration yet-a clear indication that this kind of collaborative spirit is the way for discoveries of the future as well.

"Being part of such important international research is critical to both fundamental and applied research because we can't apply science that we don't understand," noted Dr. Mauricio Sacchi, Chair of the Department of Physics. "Understanding the basic nature of how the universe works is at the heart of the next chapter in scientific research and ATLAS will now turn to helping establish what type of Higgs boson has been found."

This kind of success and commitment to research will continue to attract the caliber of faculty and graduate students to Alberta and to the University of Alberta to help solve the world's big questions.

Q & A with Dr. Roger Moore, University of Alberta (Physics)

Roger Moore is one of three University of Alberta physics professors in the ATLAS collaboration. He works on the ATLAS trigger, the system which decides when an interesting event has occurred in the detector and saves it to disk for later analysis.

What's changed between July and now?

We have a measurement of the spin of the particle that show it is consistent with a particle with zero spin which is really the crucial thing in determining that it is a Higgs boson. This makes it fundamentally different from ever other particle discovered because all other particles have some spin. Particles with half a unit of spin give us matter; particles with one unit of spin give us force, like electromagnetism. Particles with zero spin give us mass.

Are there any more proofs to do?

Yes! We would like to measure the branching ratios, the chance that the boson will decay in a particular way, such as decaying into tau particles, as well as to increase the accuracy of the branching ratios we already have.

What type of Higgs could it possibly be?

Well it could just be an 'ordinary' Standard Model Higgs. Another possibility is that it could just be the lightest Higgs in something called Supersymmetry (also known as SUSY). In these models there are five Higgs bosons, two of which have an electric charge. However, the lightest Higgs boson looks very like the Standard Model Higgs boson so we need to either see evidence of more Higgs bosons or we need to measure the branching ratios more accurately to see whether they differ (at the few percentage level) from the Standard Model Higgs.

Why does it matter to know which type?

We still have lots to explain that the Standard Model cannot. Dark matter makes up about 24 per cent of the universe - that's five to six times more than all the atomic matter - but is not made of atoms and we have no particle in the Standard Model which can explain what on earth this huge fraction of the universe is. Supersymmetry is an excellent way to explain this dark matter, so if we have a SUSY Higgs, we really want to know!

Even if SUSY isn't the answer, whatever the dark matter particle is, it will likely get its mass from the Higgs so improving our understanding the Higgs we have found might be the first way we get some idea about dark matter.

Now that the discovery has been confirmed, how else will the Large Hadron Collider be used?

Finding dark matter, I would say, is the next big challenge. There are good arguments that we should be able to create it with the higher energy after the shutdown. However, there are no guarantees!

There may be also more out there than just dark matter. In the Standard Model, you would expect the mass of the Higgs boson to be very great, but it is not. New physics, like Supersymmetry, was actually invented to explain why the Higgs is so light. It was not actually invented to solve dark matter at all: that was just a bonus! Having now found the Higgs, there is a very real possibility that there is new physics just around the corner and we do not have a clear idea exactly what it is!

What type of work are UAlberta scientists doing there?

My group works on the tau trigger (a tau is a very heavy cousin of the electron) with the aim of improving it for a Higgs to tau decay search. This is an important channel for determining whether this is a Standard Model Higgs or a SUSY Higgs.

Professor Doug Gingrich's group is studying the ATLAS experiment's sensitivity to extra-dimensional space beyond our common three dimensions, including the possibility of black holes being produced in the experiment.

James Pinfold is leading an international effort to search for the electroweak monopole, another particle predicted by the Standard Model.