Higgs Boson – update from CERN

by Nicholas Mee on November 16, 2012

Earlier this year on 4th July researchers working at the Large Hadron Collider made their epoch-making announcement that they had discovered a particle that looks very much like the long-awaited Higgs boson. It was clear that something new had turned up in the detectors of the LHC, but no-one could be absolutely certain that it really was the much expected Higgs boson.

The Best Theory That We Have!

The CMS detector in the Large Hadron Collider during construction. (Copyright CERN, Geneva.)

The best theory that we have to describe all the particles and forces observed in particle accelerators is known as the Standard Model. (This isn’t a great name, but it reflects the success of the theory and the confidence that physicists place in it.) According to the Standard Model the Higgs field is responsible for breaking the ‘electroweak’ force into two forces that we observe as the electromagnetic and weak forces. It does this by giving mass to the three particles, the W-minus, W-plus and Z-nought bosons that are responsible for producing the weak force, while leaving the photon – which is responsible for the electromagnetic force – massless. This makes the weak force feeble and very short range, while the electromagnetic force remains powerful and long range.

The Multi-tasking Higgs Boson

But the Standard Model requires more of the Higgs field. According to the Standard Model the Higgs field is also responsible for giving mass to other particles, the particles from which matter is formed, such as electrons and quarks.

A Bit of Detective Work

The Higgs boson cannot be observed directly in the detectors of the LHC. What the detectors see are the particles that the Higgs decays into. It then takes a bit of detective work to interpret these fingerprints. From the original announcement in July it seemed pretty clear that the new particle was doing the first part of the job of the Higgs, that is it was decaying into Ws and Zs and was therefore responsible for producing their mass (and breaking the electroweak force).

Mural on the building above the ATLAS detector at the Large Hadron Collider. Mural by Josef Kristofoletti. (Copyright CERN, Geneva.)

What was not so certain was whether it was also decaying into quarks and tauons (heavier relatives of the electron) at the expected rate. And was therefore also responsible for producing the mass of the electrons and quarks. The decays into tauons would be much rarer, so more data was needed to confirm the predictions.

Further Progress

A further announcement about progress at the Large Hadron Collider was made earlier this week. The detectors of the LHC have now collected twice the data that they had by the time of the original announcement and it seems as though the Standard Model predictions are holding up and the new particle really is the Standard Model Higgs boson. This is great news of course, unless you are a physicist looking for something new and surprising. (But you can’t please everyone!)

Deeper Connections

We know that the Standard Model cannot be the final answer. It is actually formed of two theories coupled together: one describes the electroweak force, the other, known as quantum chromodynamics, describes the strong force which holds quarks together to form protons and neutrons, and holds protons and neutrons together to form atomic nuclei. There must be some deeper connection between the electroweak force and the strong force that is missing from the Standard Model.

The Standard Model also fails to explain some of the most significant large scale features of the Universe, such as the fact that most of the matter that it contains seems to be formed of an unknown substance that is referred to as ‘dark matter’.

Higgs Force: Cosmic Symmetry Shattered by Nicholas Mee

An Even Better Theory

So the fact that the Standard Model predictions are holding up is a major triumph for physics, but what physicists really want are some surprises that will provide clues that will lead to a new and even better theory.

I’m sure that we won’t have to wait long before the Large Hadron Collider produces something really unexpected.

More Information

There is, of course, much more information about the search for the Higgs boson in my book Higgs Force:


Previous post:

Next post: