The Higgs boson
The particle's confirmation would stand out as one of the great scientific achievements of the 21st Century so far.
But what exactly is the Higgs boson,
and why have particle physicists spent more than 40 years searching for it?
?What is the Higgs boson
The Higgs so far definitively exists only in the minds of theoretical physicists.
There is a sturdy theory for how much of the Universe works - all of the particles that make up atoms and molecules and all the matter we see,
most of the forces that direct them,
and a small zoo of more exotic particles.
This is called the Standard Model. However,
there is a glaring hole in the theory: it does not explain how it is that some of those particles gain their mass.
The Higgs mechanism was proposed in 1964 by six physicists,
including the Edinburgh-based theoretician Peter Higgs,
as an explanation to fill this hole.
?What is so important about mass
Mass is, quite simply, a measure of how much stuff an object - a particle, a molecule, or a Yorkshire terrier - contains.
If not for mass, all of the fundamental particles that make up atoms and terriers would whiz around at light speed,
and the Universe as we know it could not have clumped up into matter.
The Higgs mechanism proposes that there is a field permeating the Universe - the Higgs field - that allows particles to obtain their mass.
Interactions with the field - with the Higgs bosons that come from it - are purported to give particles mass.
This is not unlike a field of snow, in which trudging through impedes progress; your shoes interacting with snow particles slows you down...
?How do scientists search for the Higgs boson
Ironically, the Standard Model does not predict an exact mass for the Higgs itself. Particle accelerators such as the LHC are used to systematically search for the particle over a range of masses where it could plausibly be.
The LHC works by smashing together two beams of the sub-atomic particles called protons at close to light-speed.
This generates a vast shower of particles that are only created at high energies.
The Higgs will probably never be observed directly, but scientists at the LHC have been looking for a Higgs that fleetingly exists in this soup of particles.
If it behaves as researchers think it will,
it should decay further into yet more particles, leaving a trail that proves its existence.
It is not the first machine to hunt for the particle. The LEP machine, which ran at Cern from 1989-2000, ruled out the Higgs up to a certain mass,
and until it was switched off in 2011, the US Tevatron accelerator searched for the particle above this range.
the Tevatron team released their final analysis, which tantalisingly points to a particle much like the one that the LHC data suggests...