Our dear boson – and so what?

A long-sought particle finally found. On Wednesday 4 July, enthusiasm spread from CERN to the worldwide media. But a question legitimately arises: why is this particle attracting so much interest? In other words, how is it different from all the others? (And, by the way, what is a boson?).


CERN, 4 July 2012: a long-sought particle finally found.

Strictly speaking, we cannot even call it the “Higgs” boson yet. Only after careful checking of its properties will physicists be able to say if the new boson corresponds to the particle that theorists predicted in 1964. However, the experimental data we have so far already tells us, unambiguously, that this new particle is different from all the other elementary particles we know.

“Every particle is either a boson or a fermion,” explains John Ellis, former CERN theorist and currently professor at King's College in London. “All known particles spin like small tops, with the known bosons that carry the fundamental interactions – such as the photon, the quantum of light that carries the electromagnetic force – spinning at twice the rate of the fermion particles that make up matter particles such as electrons and quarks.”

A practical application of the spin of nuclear particles is magnetic resonance imaging (MRI), a technique used for the early detection of a number of diseases. In order to produce high-resolution images of organs to facilitate medical diagnoses, MRI analyses the alignment of nuclear spins.

“Since the newly discovered particle decays into pairs of known bosons, it is certainly also a boson,” says Ignatios Antoniadis, Head of CERN’s Theory Unit. “However, we also see that it does not spin the same way as a photon. If it were a Higgs boson, it would not spin at all. This is what physicists call a scalar boson, and it would be the first elementary scalar boson ever seen. However, we cannot yet exclude the possibility that the new particle spins at a larger rate than a photon.”

Either way, the newly discovered particle would be the first of a new class of particles. Will this change our everyday lives? The question has no immediate answer because history tells us that any practical application – such as the above example of MRI – might take years to develop or might never really happen. However, whatever the future brings, physicists can already see that the new particle holds important information that will provide new insight into the workings of the Universe. Nature still holds many mysteries, and understanding this one may unlock the doors to others…

by Antonella Del Rosso