Q&A: Brown physicist on the Higgs boson and whether it might change the fate of the universe

PROVIDENCE, R.I. [Brown University] - On July 4, 2012, researchers at the Large Hadron Collider (LHC) in Switzerland announced with great fanfare that they had successfully detected the Higgs boson, the manifestation of the mechanism that gives some elementary particles their mass. The finding was a triumph of both the experimental skill required to definitively detect the particle, and the theoretical acumen of those who predicted its existence, recognized by the 2013 Nobel Prize in Physics.

Brown University researchers played key roles in both sides of the accomplishment. Experimentalists including David Cutts, Ulrich Heintz, Greg Landsberg and the late Meenakshi Narain made key contributions to the Compact Muon Solenoid (CMS) experiment at the LHC credited with making the discovery. Years earlier, the late Gerald Guralnik was part of a group that made a theoretical prediction of the particle, which many scientists believe to be the most complete description of the Higgs mechanism.

The Higgs was the final missing piece in the standard model of particle physics - the theory that describes the basic building blocks of the universe. But its discovery was by no means a final destination for particle physics. Fundamental questions about the Higgs itself remain unanswered.

In late October, physicists from around the world gathered at Brown for the annual Higgs Conference to discuss these questions and more. This year's conference, held at Brown for the first time, was organized by Gaetano Barone and Loukas Gouskos, both assistant professors at Brown and part of a group of early-career particle experimentalists that includes assistant professors Matt LeBlanc and Jennifer Roloff.

Gouskos talked about the conference in an interview.

Q: Could you tell us a little about the Higgs boson and its significance?

It's a particle that we discovered over a decade ago, and it was very elusive. We were looking for it exhaustively for about 50 years. It's the particle associated with the Higgs field, which permeates the universe. Interactions with this field set the masses of quarks and charged leptons - the building blocks of matter as well as the massive force carriers. So it's fundamental to everything we know about the universe.

Q: Now that it's been found, what are some of the open questions surrounding it?

The discovery of the particle wasn't the end of the story, as many people may think. It actually opened a whole new chapter of exploration. We want to understand how strongly it interacts to other particles and also to itself, whether it interacts with particles beyond those predicted by the Standard Model and more. Any deviation from the Standard Model predictions could point to new particles or forces. Some Higgs couplings are still known only at the 10% level or event less. Others are far more weakly constrained or not yet established. So there's lots to learn.

Understanding these interactions is connected to some of the deepest questions about the universe. For instance, precision measurements of how the Higgs couples to other particles and to itself could relate to why matter dominates over antimatter - hence why we exist. It could also offer clues to the particle nature of dark matter.

We also want to understand the Higgs potential - the energy landscape of the Higgs field from which the particle is produced. We know, now that we've discovered the particle, what the minimum of that Higgs potential is, but we don't know whether that's a universal minimum, or whether it could actually quantum tunnel to a lower energy state. If that happened, it would completely change the fate of the universe! But we shouldn't worry (yet). Current data imply lifetimes vastly longer than the age of the universe.

Q: Can you tell us more about the conference and how it will address some of these questions?

This is the most prestigious conference dedicated to the Higgs boson. We have around 130 people attending this year. We opened with plenary overviews of the current status-what the LHC experiments and theory tell us today - then moved to focused sessions on where to push next. A major theme is "tools for precision" by which we mean the detectors we operate now and plan for the future and the algorithms, analysis and AI methods that turn data into measurements. In the near term, we'll map plans for the LHC and its next, higher-intensity phase. Looking further ahead, we'll discuss the next multi-billion-dollar collider project - what it would look like, why it's needed, and how much farther it could push our understanding of the Higgs.

Q: What does it mean for Brown to host this conference?

I hope this puts Brown even more clearly on the map as a central point in Higgs and particle physics in general. Moreover, I believe this conference will spark interest and attention from other disciplines here at Brown - for instance engineering and computer science. There are a lot of connections between the techniques we use and that are used in those disciplines.

It's also great for our students, who get to meet a lot of people and realize how important is what we are doing here, and also what it takes to become a successful scientist. It's really a great opportunity.