Nobel prize in physics: it's not too soon for a Higgs boson to win it

I would be happy for it to be wrong, but the pundit consensus seems to be that this year's Nobel prize for physics, to be announced on Tuesday, will not be awarded to anything related to the newly discovered boson announced on the fourth of July this year.

I have seen a couple of reasons advanced for this.

One is that the committee just couldn't respond within a couple of months. It's true that nominations closed in February, but I would have thought quite a few submissions would have said "give to this, if it happens". Projecting from the hints in December last year (on the assumption that they were not just noise) and the performance of the Large Hadron Collider, one might have expected the discovery to come about now, rather than in July, but the experiment did well and we got a bit lucky. Since the original theoretical work was done in the early sixties, and the December 2011 hints were pretty suggestive, this can't have been a complete surprise. I would hope the committee was not taken unawares.

Of course they have a tricky job; there are several (more than the maximum three!) theoretical physicists who could reasonably hope for a share in the prize. And there are the two experiments* and the accelerator that are responsible for the discovery. Despite the collaborative nature of science, the award has never been made to a collaboration or organisation, but they could conceivably pick representative individuals. Which would only make the decision harder.

A second reason given is that there is still doubt over the discovery. I don't buy this. There is no doubt that a new boson has been found; the only doubt is over whether it is exactly the Standard Model Higgs boson. Everything we have measured about the new particle so far is consistent with the expectations of the Standard Model – see for example this conference summary from ATLAS – and that's fine, but it's not exactly the point.

The key thing about the Higgs boson is its relationship to the electromagnetic and weak nuclear forces. These forces have a similar strength at high energies, but are very different in everyday life. The reason for the difference is the mass of the W and Z bosons, which carry the weak force. Adding this mass in to the theory in an ad hoc way breaks a key symmetry of the theory, and causes all kinds of problems (the theory would not be renormalisable, and as the Nobel committee recognised in 1999 this is a necessary property for any fundamental theory).

The Higgs boson is the evidence that a hidden symmetry mechanism, developed by several theorists in the early sixties, is actually present in nature. The connection with the W and the Z is really intimate, via polarisation states.

Light - photons - has only two possible polarisations at a time. It can be split into left and right circularly polarised states for example. This is another way of saying that the photon, the quantum of light, only has two possible spin states. The spin of a photon can point along its direction of motion, or against it, but never perpendicular. That's actually a consequence of the fact that the photon has no mass, and so can only ever travel at the speed of light. Einstein always gets in there somewhere.

Polarisation, by the way, is not so far from everyday life. When sunlight hits a shiny surface, for example, one particular polarisation of the light is preferentially reflected. Polaroid sunglasses are made such that the lenses do not allow that polarisation through, and so reflected glare is reduced more than is direct light.

Anyway, a massive version of the photon would have a third possible polarisation state, because the spin could indeed point perpendicular to the direction of motion. So when you add mass to the W and Z, you have to add an extra degree of freedom too. This degree of freedom is generated by the same "hidden symmetry" mechanism that means the Higgs boson has to exist. There is a sense in which one third of every W boson, and one third of every Z, is a Higgs. This intimate connection is required by the symmetries; it also dictates the rate at which Higgs bosons decay into pairs of W or Z bosons.

The fact that the new boson decays into W and Z bosons at the right rate, within the current experimental precision, is enough for me to say that it is some kind of Higgs boson, and nothing more is needed to award a prize for it.

There are lots of possible variants of the "Higgs" boson – supersymmetric ones, composite ones, whatever. This might be a Higgs boson but not the Higgs boson. But what matters is that this new boson is connected to the W and Z in a way that is so close to the way a Higgs boson should be that it must be playing a key role in electroweak symmetry breaking, along the lines proposed by those theorists all that time ago.

There's no such thing as utter certainty in science, but the balance of probabilities is sometimes overwhelming, and I think this is one of those times.

Of course, a third possible reason is that a more timely or important bit of physics must be awarded the prize this year; in which case I'll be very excited to hear about it. I am sure whoever wins it will be thoroughly deserving, even if not everyone who is deserving can win. Fortunately, the science is much more important than the prize anyway.

* Declaration of interest: I am a member of the ATLAS collaboration!