Hooray for Higgs!

It’s a big night and you can read the news pretty much everywhere on the web, but I have to get in on the action: it looks like the Higgs boson has been discovered at the Large Hadron Collider.

The Large Hadron Collider, or LHC, is of course an enormous piece of physics equipment located in Switzerland at the European Organisation for Nuclear Research, or CERN (originally the Conseil Européen pour la Recherche Nucléaire, thanks to those wacky French-Swiss). Two experimental teams, known as ATLAS and CMS, have used the LHC to search for Higgs bosons in the debris from the high-energy particle collisions it generates.

Both experiments appear to have found something that looks a lot like a Higgs boson, with a mass of between 125 and 126 GeV (ATLAS got 126.5 GeV, CMS got 125.3 GeV, so that’s pretty close).

Is this the end of physics? That’s a big call, and one that sensibly no one’s willing to make. But there’s certainly a bit of “where do we go from here?”

Before this, the last major discovery of a fundamental particle was the top quark in 1995, and that time there was a much bigger concern that if we didn’t find it then much of what we knew about particle physics must be wrong. But the Higgs boson leaves many unanswered questions, and many of us were hoping that they’d find something more, well, unexpected.

Of course, there’s still unexplained physics staring us in the face, like dark matter, dark energy, inflation and that little thing called gravity. And the Higgs signal isn’t quite as predicted, which could either mean new physics or we just need more data. But for the moment, the Standard Model holds strong, and we should celebrate by boozing on for the boson.

Come back soon for a more considered discussion of what this discovery does and doesn’t mean, and until then maybe check out the unofficially combined ATLAS and CMS results on the viXra blog. And a brief explanation of terminology below:

• Higgs boson – a quantum excitation of the Higgs field.
• Higgs field – a kind of energy field that fills all of space and gives mass to everything that interacts with it. Unfortunately at this stage those masses are purely arbitrary – it would be nice if we had a theory that told us what they should be.
• Mass – you already know what this is, but it’s worth pointing out that most of the mass we can see (i.e., not dark matter) is actually due to potential energy from the forces that bind quarks into protons and neutrons, via E = mc². The Higgs field is responsible for the masses of electrons and unbound quarks, which are much smaller.
• GeV – also known as giga electron volts, is 1 billion electron volts. And an electron volt is the energy a single electron gains by being accelerated through one volt of an electrical circuit. This energy can be related back to mass via the aforementioned E = mc² (the correct nomenclature for mass is actually eV/c², but no one’s really fussy about it).
• Hadron – a particle made out of quarks. Protons and neutrons are the best known hadrons, and protons are the things that the Large Hadron Collider accelerates and collides. They’re quite large relative to their constituent quarks, but I think the LHC gets its name from the fact that it itself is rather large (27 km around).
• Boson – to put it simply, bosons (with an s that sounds like a z, not to be confused with bosuns) are particles that transmit forces between fermions, which are the particles of matter. And to put it complicatedly, bosons obey Bose-Einstein statistics and fermions obey Fermi-Dirac statistics.
• Standard Model – a theory put together in the 1970s that describes all observed interactions of fundamental particles. It includes the matter particles, or fermions, namely 6 types of quarks and 6 types of leptons (which include electrons and neutrinos), and the bosons for the forces that act between them, namely the photon (the quantum of the electromagnetic force), the W and Z bosons (of the weak nuclear force, which causes radioactive decay) and gluons (the strong magnetic force, which binds quarks into hadrons and is so strong you can’t pull them out and get a quark on its own). It also includes the Higgs boson (see above). It doesn’t include gravity, because that’s the weakest of the four fundamental forces and cannot so far be detected in particle accelerators.
• Dark matter, dark energy and inflation – these are cosmic entities whose effects can only be seen via gravity on a galactic or universal scale, and which we’ve discussed before. They are also not described in the Standard Model, but they seem to be real. So there, Horatio.