What is the Higgs Boson? Why should we care?
On July 4th, CERN announced that a new particle had been observed with a mass of around 125-126 GeV. This incredibly exciting news didn’t much affect me as a physics Ph.D. student – I study quantum optics, so I really have no specialised knowledge about particle physics – but I experienced the announcement as someone in awe of the extraordinary ingenuity and hard work that culminated in experimentally discovering the last fundamental piece of the Standard Model of particle physics.
Most of what I know about the Higgs boson I actually learned from the two excellent MinutePhysics videos on Youtube: Part I explains why a “yeasty Higgs field” is the necessary ingredient to give particles mass, and that the Higgs boson is an excitation left over from this field; and Part II explains what we actually mean when we talk about “mass“.
Peter Higgs is the theoretical physicist at the University of Edinburgh after whom the Higgs boson is named, for explaining back in 1964 how particles acquire mass. In fact, five other people also published papers giving similar explanations that year, which is why Higgs, with the Belgians Englert and Brout, along with Guralnik, Hagen and Kibble, all shared the 2010 J. J. Sakurai Prize for their joint contribution. Higgs, Englert, Guralnik and Hagen attended the Higgs update seminar on July 4 in Geneva. When Higgs was asked a question by the media, he reportedly declined to answer, saying that he thought the day belonged to the experimentalists. I liked that anecdote, for the modesty it evokes, but also for reminding us that the LHC is the result of the labour of thousands of people over the course of many years, who cannot hope to be individually recognised for their collective achievement.
Looking at the initial data sets released by the ATLAS and CMS projects at the LHC gave me some small sense of the level of sophistication involved in these experiments. By combining data from different signals that could indicate the existence of the Higgs boson, the teams were able to assign a 5 sigma (standard deviation) statistical significance to their discovery, meaning that the probability of background fluctuations alone producing the observed signal is approximately 1 in 3 million.
There should be a lot of exciting news yet to come from this initial data, and the data to follow. Researchers around the world will be analysing the findings, to determine exactly what kind of a Higgs particle the evidence is pointing towards, and whether the results can rule out some theoretical models, or hint at something beyond the Standard Model that could answer outstanding questions that the SM doesn’t explain.
Not all the excitement at CERN is generated by fundamental physics, though – the world-wide scientific collaboration has inspired a decent amount of artistic output. This suggests to me that many people not working directly in particle physics nevertheless wish to be a part of this exciting enterprise, in some capacity. I think it’s safe to say that, even before this discovery was announced, the LHC had captured a lot of imaginations and come to symbolize the world’s scientific aspirations. The announcement of this discovery might also stimulate conversation about other topics in science and research: Will Europe continue to outpace the United States in particle physics research? Is there a future for corporate-funded basic research? Should publicly-funded research automatically be freely available to any member of the public? And can opinion polls be scientific?
The successful collaboration at CERN underlines the global nature of basic research today. Maybe that’s simply a reflection of the fact that as our understanding advances, the experiments become more complex and require greater cooperation. But it’s also thrilling to know that everyone has a real reason to celebrate this historic discovery.
Sacha Kocsis is a physicist at Griffith University in Brisbane. His work has been published in Science.