WHAT IS A HIGGS BOSON?
The Higgs boson (regular Wikipedia entry, Simple English Wikipedia entry) is the elementary particle that gives matter mass. Many of us have probably heard about Einstein's famous equation:
|This image is taken from Wikipedia.|
But, if we convert energy into mass, where does this mass come from? The Standard Model, which is the working description of how the fundamental particles interact (I talked about this in my post discussing gravitons), says it comes from the Higgs field. This is a field similar to the electric field and the magnetic field (more on fields in general here). At the instant after the Big Bang, all particles moved at the speed of light (c from above) since none of them had mass because there was no Higgs field. In the next instant (about a trillionth of a second later), the Higgs field came into existence and produced a resistance to particles based on what they were made of. This resistance manifests itself as mass: the slower a particle moves through the Higgs field, the more massive it is. The Standard Model also allows fields to manifest themselves as particles (the photon is the particle associated with the electric and magnetic fields). Therefore, this Higgs field should also manifest itself as a particle and we call it the Higgs boson.
The only particle from the Standard Model that has not been detected is this Higgs boson. (Note that gravity is not described by the Standard Model.) This is because the Higgs boson is very massive for a fundamental particle at about 133 times the mass of a proton. The amount of energy conversion needed to produce this mass is much larger than we have been able to create in the past. That is, until CERN built the Large Hadron Collider (LHC)...
WHAT DID CERN SEE?
|View of the CMS experiment [note the person near the center] (© CERN)|
CERN is the home to several experiments including CMS and ATLAS. Both of these experiments smash together protons with very large energies. The protons and their energy can change into a Higgs boson (if there is enough energy). The Higgs boson decays (changes into something else) almost immediately, so the LHC experiments look for the Higgs boson's signature in the resulting particles. There are 5 pairs of particles that result from the decay of a Higgs boson, including 2 photons.
Both CMS and ATLAS saw the Higgs signature in 2 of the 5 different resulting decay pairs. Only CMS had sufficient data to look for all 5 kinds of decay pairs and saw with high certainty signatures in 4 of the pairs. More research is needed for the signature CMS didn't see.
|Diagram of the ATLAS experiment [note the people on the bottom left] (© CERN)|
WHY IT'S A BIG DEAL!
The official conclusion is that CERN has indeed observed a Higgs-like particle. "Higgs-like" does not mean that they are unsure if they found what they were looking for. Instead, it appears that the Higgs boson they observed has more properties to it than the Standard Model predicted. The LHC has found what it is looking for as well as hints that there is new physics to be discovered.
So this is the big deal: the population of the Standard Model is complete but the model itself doesn't appear to describe everything. That is something we knew before, but now we are seeing it with the apparent complication in what was and wasn't observed in the discovery of the Higgs boson.
I am a physicist because every time you discover something new, not only do you understand the Universe better, but you have even more exciting questions to answer! Soon enough, it is going to be gravitational waves stirring up excitement like this and I am going to be in the midst of it all!
IT'S NOT THE 'GOD PARTICLE'
The Higgs boson is sometimes referred to as the "God particle," especially by the media. However, it has nothing more to do with God than any other particle in the Universe. The origin of this misnomer is a book by Nobel Laureate Leon Lederman titled The God Particle: If the Universe Is the Answer, What Is the Question?. Likening the Higgs boson as a God particle refers to it being the origin of all matter's mass. Physicists (like me as well as Lederman himself) generally dislike this nickname since it places much more import on this particle than it deserves. But above that, it is offensive to people of faith and makes us look like we are trying to replace God. We aren't.
Want More? ...
Watch the announcement seminar
Read the official CERN press release