The Higgs boson or Higgs particle is an elementary particle in the Standard Model of particle physics. Its main relevance is that it allows scientists to explore the Higgs field â€“ a fundamental field first suspected to exist in the 1960s that unlike the more familiar electromagnetic field cannot be "turned off", but instead takes a non-zero constant value almost everywhere.
For a subatomic particle that remained hidden for nearly 50 years, the Higgs boson is turning out to be remarkably well behaved.
Yet more evidence from the world's largest particle accelerator, the Large Hadron Collider (LHC) in Switzerland, confirms that the Higgs boson particle, thought to explain why other particles have mass, acts just as predicted by the Standard Model, the dominant physics theory that describes the menagerie of subatomic particles that make up the universe.
The new results show that the Higgs boson decays into subatomic particles that carry matter called fermions â€” in particular, it decays into a heavier brother particle of the electron called a tau lepton. This decay has been predicted by the Standard Model. Even so, the findings are a bit of a disappointment for physicists who were hoping for hints of completely new physics.
On July 4th, 2012, the discovery of a new particle with a mass between 125 and 127 GeV/c2 was announced; physicists suspected that it was the Higgs boson, an elusive particle first proposed 50 years ago by English physicist Peter Higgs. In Higgs' conception, in the blink after the Big Bang, an energy field, now dubbed the Higgs field, emerged that imparts mass to the subatomic particles that trawl through it. Particles that are "stickier" and slow down more while traversing the field become heavier.
Because subatomic particles are either matter carriers called fermions, such as electrons and protons, or force-carrying particles called bosons, such as photons and gluons, the existence of the Higgs field implied an associated force-carrying particle, called the Higgs boson, which is like a ripple in that field.
The 2012 discovery left little doubt that the Higgs boson exists, however, there were still many unanswered questions. Is there one Higgs boson or multiple? If there are multiple, what are their masses? And just how do these different-flavored Higgs behave?
To answer those questions, physicists still had to pore over tons of data from the LHC, which accelerates protons to just below the speed of light, then smashes them together, creating a shower of subatomic particles.
When the LHC collaborators analyzed those Higgs events, they found about 6 percent of the elusive particles decayed into tau leptons. And though not unexpected, the new results show no hint of additional Higgs bosons that would lend credence to alternate theories such as supersymmetry, which predicts that every particle currently known has a "superpartner" with slightly different properties. The idea of the Higgs decaying to tau leptons was somewhat tacked onto the Standard Model after its creation, yet this addition to the Standard model turns out to be how nature does it.
But there are still a few pieces left to complete the picture predicted by the Standard Model.