Higgs researchers hit the jackpot

5^th July 2012

Emma Roscow

Emma Roscow

5 July 2012

A boson has been born.  The midwifery feat of particle physics was confirmed yesterday at CERN near Geneva and the particle announced to the world as the Higgs, bringing an end to the gestation period of the Standard Model and bringing to life new possibilities for exploring the particle responsible for gravity.

“It is an incredible thing that it has happened in my lifetime,” the 83-year-old namesake and father of the boson, Peter Higgs, said at the assembly at CERN.  After almost 50 years of intense speculation – during which Prof Higgs and his colleagues were even accused of failing to understand the laws of physics – the announcement confirms the final piece of the jigsaw for the Standard Model of fundamental particles, which has dominated and driven research for the last half a century.

Just as all materials in the universe are comprised of a few dozen elements that make up the periodic table, all fundamental particles (which make up the elements) are represented in the Standard Model: quarks, leptons and force-carrying bosons.  The question was how these particles acquire mass; the Higgs boson was the answer.  Particles roam around in a Higgs field, interacting with the Higgs boson in order to generate the force that binds stars and planets together.  The moniker of “God particle,” often used to illustrate its elusive and indispensable nature, refers to its role in creating cosmic masses like galaxies during the Big Bang which would otherwise be uniformly distributed, free-floating particles, if it weren’t for the presence of a gravitational force to clump them together.  (In fact, just as appropriately, legend has it that physicist Leon Lederman wanted to name it the “goddamn particle” for its stubbornness in refusing to be detected, but his editor forced him to change it to God particle instead.)

What does a “discovery” mean for the stubborn particle?  In a domain as indifferent to everyday methods of observation as particle physics – which involves particles so small they do not reflect light, leaving even the most powerful light-based microscope blind to them – it is impossible to be certain about anything.  Two independent proton-smashing studies in the Large Hadron Collider, detecting with tremendous precision any kinks in the data that might hint at the presence of the new boson, converge on the findings you would expect if the Higgs did exist.

The Higgs decays very quickly into smaller, more stable particles: it may decay into two protons for example, or two Z bosons which then each break down into two electrons or two muons.  The teams’ task was to sift through the data to find this kind of Higgs debris.  It is, hypothetically speaking, possible that either these results are a highly coincidental fluke, or that it is some other new boson that has been discovered – but this is as close to certainty as it gets.  Together, the studies reached the coveted five sigma level of probability, meaning there is less than one in a million chance that they are both flukes.

What’s next?  “The discovery of a particle consistent with the Higgs boson opens the way to more detailed studies, requiring larger statistics, which will pin down the new particle’s properties, and is likely to shed light on other mysteries of our universe,” CERN director-general Rolf Heuer announced near Geneva.

Oddly, some fundamental particles have mass – like the proton and the neutron – some are extremely heavy, like the W and Z bosons, and yet the photons and gluons have no mass at all.  The discovery of the Higgs is exciting, but it remains to be understood why it couples with other particles the way it does, or why these particles have the masses they have.

There is still little known about the particle: it is so mysterious that the scientific community was divided over whether it existed right up until the last moment.  Stephen Hawking had placed a $100 bet that it didn’t exist.  What has been confirmed is the discovery of a particle that fits what a Higgs boson should be: the challenge now is to confirm how close to the Higgs theory the particle conforms.  “We know it is a new boson,” Oliver Buchmueller, part of one of the research teams, said: “but we still have to prove definitively that it is the one Higgs predicted.”

Emma Roscow