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Physicist Tony Liss, expert on the Higgs boson particle

10/8/2013  8:00 am

On Tuesday, Oct. 8, the Nobel Prize in physics was awarded to Peter Higgs and Francois Englert for their theories predicting the Higgs boson and its associated field, which interacts with other particles to give matter mass. Physics professor Tony Liss, a member of the ATLAS project at CERN (Illinois physics colleagues Steve Errede and Mark Neubauer were also part of the project), which discovered the particle in 2012, talked about the big implications of the tiny particle in an interview with News Bureau physical sciences editor Liz Ahlberg.

What is the Higgs boson particle?

Tony LissI don’t know a way to avoid being at least a little technical here. The Higgs particle is the excitation of the Higgs field, just as the photon is a particle that is the excitation of the electromagnetic field. The theory says that all the other known particles interact with the Higgs field, and that interaction gives them mass. A way to think about this is that there is energy associated with the particles interacting with the Higgs field and E=Mc2, so that interaction energy is their mass.

When was it first hypothesized? Where did the idea come from?

The idea for the “Higgs mechanism” came from a similar mechanism in superconductivity. A theory of the interactions of fundamental particles, which later became known as the Standard Model of Particle Physics, was coming together in the early 1960s. But the mathematics of the theory only worked if the particles were massless.

The Higgs mechanism was invoked in 1964 to solve this problem and give the particles mass. At the time, and right up until the discovery of the particle in 2012, the Higgs mechanism was thought to be a clever, relatively simple, idea. But it was far from clear that it was the correct solution. What is so amazing about the Higgs discovery is that this “simple” idea didn’t have to be correct, but it turns out it is!

CERN finally announced the discovery of the particle in 2012. Why did physicists look for it for so long?

It’s hard to make Higgs particles and once made, they are hard to identify among all the other stuff that goes on. Add to that the fact that we only had a vague idea of what the Higgs particle’s mass was, so we didn’t even know very well where to look.

What we still don’t know, is if there is just one Higgs particle or a family. In other words, do all the particles get their mass from interactions with the Higgs particle we’ve found, or is there more to the story?

What is the impact of finding the Higgs on our current understanding of the universe?

The universe would be a dramatically different place without a mechanism to give the fundamental particles mass. So now we have a start on understanding exactly how these particles acquire mass. The fact that we found the Higgs particle in the mass range we did is nice because the theory predicts a fairly complex pattern of decays of the Higgs at that mass, which means we have a lot of things to study that allow us to test the details of the theory and see if it’s completely correct.

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