The elusive Higgs boson

I'm pleased to hear (Autumn 2009) that the Large Hadron Collider shall soon be back in service. One of the main reasons for its existence is to search for Higgs Bosons. I believe I am not alone in this, but I can only speak clearly for myself, so I shall stick with the first person singular: I do not believe the Higgs boson exists.

Of course, saying that publicly may – via Murphy's Law – make its imminent discovery inevitable. In such a case I shall be proven wrong and shall welcome the proof. Science does that – both sides of it; proving things and accepting proof. In any case, I am glad the LHC has been built and shall search for the Higgs boson. If it finds some, we'll have resolved an important question: if it does not, we'll have significant evidence (but not proof) that it doesn't exist. In the mean time, the LHC shall collect a truly vast quantity of data on the details of the Standard Model of particle physics; collecting that data is, in my opinion, important in its own right.

So, the public (i.e. you) might reasonably ask, what is this Higgs boson, and why's it such a big deal ? The standard model's one flaw is that it fails to account for the masses of the particles it describes: it cannot explain why the proton and neutron have nearly two thousand times the mass of the electron, for example. There is a theoretical construct, called the Higgs field, that provides a mechanism for the standard model to account for these masses; and a natural consequence of a field, in quantum field theory, is an associated boson. Just as the electromagnetic field gives rise to the photon, the Higgs field gives rise to a Higgs boson.

When the standard model was developed, in the 1970s (with plenty of lead-in from before), its account of the weak interaction, which mediates nuclear decay and other kinds of transmutation, was expressed in terms of new fields which implied the existence of two bosons, called W and Z. It made predictions as to their masses (given the masses of other particles), on the order of a hundred times the mass of a nucleon (proton or neutron) – heavier than iron atoms. In the early 1980s, the W and Z were found and matched predictions.

"Lieutenant, please fetch boatswain Higgs for me"
     "Er…I'm sorry sir, but nobody can find him" Contrast this tale with that of the Higgs boson: it was initially hoped that the then-existing collider at CERN might be powerful enough to find the Higgs. The shut-down of CERN prior to the massive upgrade to the LHC was delayed to push its range to what was hoped would find the Higgs boson. To no avail: theoreticians went back to the drawing board and revised their models to justify believing that the Higgs boson was more massive than that.

Now, I'm not complaining at theoreticians doing that – the Higgs theory is the best account we have of the masses in the standard model, so working out how it has to be adapted to fit the data is the best they can do – but I always get uncomfortable about a theory that's so vague that we could be left revising it endlessly to account for negative experimental results, without ever quite being able to reject it. On its own, that wouldn't (yet) be a reason to reject the Higgs model; although it is grounds to look for what other theories we can reasonably build.

I find the Higgs theory æsthetically displeasing: it feels bolted on to the standard model. It feels wrong. So I'm thinking about what else we can do.

Post script (Summer 2011): the LHC's experiments proceed apace and the data remain unclear on the Higgs boson, although there are hopes that the situation should be clearer (one way or the other) by the end of 2011.

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