The Large Hadron Collider, where the Higgs boson was observed on July 4, is the world’s largest and highest-energy particle accelerator. It lies in a tunnel 17 miles in circumference beneath the border of France and Switzerland near Geneva.
Last week, Per Berglund, associate professor of physics, had a front-row seat to his field’s largest discovery in half a century. This summer Berglund, a string theorist, has been doing research at CERN (the acronym for the European Organization of Nuclear Research) in Geneva, Switzerland, home of the Large Hadron Collider (LHC) particle accelerator. That’s where, on July 4, scientists confirmed discovery of what is likely the Higgs boson, a subatomic particle that gives other particles mass. He shares the excitement with Media Relations’ Beth Potier.
Beth Potier: Where did you watch the announcement? What was the mood?
Per Berglund: The announcement (which was in the form of a scientific seminar) was held in the main auditorium at CERN. Some people (mostly students), apparently, slept outside the entrance in order to be able to get seats -- imagine rock concert-type lines. So I didn't even try to go there. However, the seminar was broadcast to several other places at CERN so I just watched and listened to the presentation in the theory common room. Even there it was standing room only, but well worth it to stand for two hours for the most important announcement in particle physics for several decades. On a personal note, I told my daughters that we had to be extra early that morning, so I wouldn't be late for the most important day of my career as a physicist.
People were clearly excited and there was big and long applause when the final results were presented by the two experiments (from the particle detectors CMS and ATLAS) that they indeed had discovered the (or a) Higgs boson.
Potier: Why should non-physicists get excited about this discovery?
Berglund: This is a great triumph for science in general, and of course for experimental and theoretical elementary particle physics in particular. For many decades there has been work to improve our understanding of the basic building blocks in nature. The Higgs is in some sense both the end of an era and the beginning of something new, in the sense that it completes our current picture, the so-called Standard Model of elementary particle physics. The hope and expectation is that this is just the tip of the iceberg, and that LHC will discover many new particles and phenomena in the years to come. In fact, what was announced as the discovery of the Higgs particle may itself in fact be a closely related particle, or particles, associated with a new feature of nature, supersymmetry. By the end of this year, the expectation is that there will be sufficient data to determine what kind of Higgs particle it is.
So, for non-physicists and non-scientists, this is one further, very important step in improving our understanding of the universe, much like basic research in any field of science brings us answers to fundamental questions about the world around us.
Potier: What does this mean to your work as a string theorist?
Berglund: As a theoretical physicist I am not directly involved in the experimental work done at CERN, though I have been visiting CERN for the last 20+ years, having first come here as a graduate student in '91 when it was thought that the Higgs would be discovered at the previous accelerator at CERN, LEP, whose tunnel is now housing the LHC. CERN has a very large theoretical physics group -- at any given time there are well over 100 of my colleagues here. Many of them are working on models very closely related to the experimental research done at ATLAS and CMS (as well as the other detectors at LHC), while others, like myself, work on string theory. String theory, which provides a unified microscopic picture of all the forces, including a quantum description of gravity, predicts the existence of extra dimensions. Although too small to detect (yet), the properties, such as the size and shape, of these extra dimensional spaces encode why our universe looks the way it does. As with any extension of our current understanding, string theory has to be consistent with the observations. The discovery of the Higgs (or a close cousin) will therefor provide important constraints that will guide us as we work on making contact between the physical and mathematical aspects of string theory and the observations at LHC, now and in the future.
Learn more about Per Berglund: http://www.ceps.unh.edu/physics/faculty/berglund.html
Learn more about CERN, the LHC and the Higgs boson: http://press.web.cern.ch/press/PressReleases/Releases2012/PR17.12E.html