What does the news tell us?

With strong evidence of a new particle with a mass around 125-126 GeV, will our interpretation of the Universe change? In an interview with the Bulletin, CERN theorist Ignatios Antoniadis explains.


The Main CERN Auditorium this morning, Wednesday 4 July.

Is today’s news an answer or the first of a new set of questions about Nature?

Ignatios Antoniadis: Based on the current data, this new particle looks like the long awaited Higgs boson. In this respect, the result is an important answer. However, the properties of the new particle have not been fully studied yet and therefore a final label will only come after further investigations.

The next step will be looking into the new particle’s decay rates. Together with mass, decay rates characterize particles. If we find that this new particle decays in the ways expected and with the rates expected from the Standard Model, we will be able to really identify it with the particle responsible for the electroweak symmetry breaking (*).


Antoniadis: Otherwise we will have to understand whether the Standard Model needs small adjustments to include the existence of the new particle or if new physics processes need to be looked for in order to explain its nature.

Let’s stay with the Standard Model. What is the new particle telling us?

Antoniadis: If the new particle is confirmed to be a Standard Model Higgs boson, then we must observe that it is relatively light, perhaps lighter that what a large part of the community was expecting up until just a few months ago.

The Higgs field associated with the boson would still permeate the Universe but it may need to be partly reinterpreted. Given the low mass of the boson, the potential that describes the field could for instance present two minima instead of just one. The universe is currently set in one of the two minima but quantum mechanics could allow for a transition to the second minimum. This, in my opinion, might signal the existence of some new physics that would compensate for this instability (**).

Has the current result already ruled out some previously possible descriptions of the Universe?

Antoniadis: Yes. Because of its low mass, such a Higgs boson would allow us to rule out theories known as “Technicolor” and some of the theoretical models used in Supersymmetry. However, other supersymmetric or not scenarios could still apply, as well as extra-dimensional theories.

Let’s now leave the Standard Model for a moment. What is the new particle telling us?

Antoniadis: The new particle could have properties that are not those predicted by our current theories. In this case, in order to unveil the theoretical scenarios to fit the new description of the Universe we would need to know exactly what its decay modes and rates are. The good news for theorists is that experimentalists may be able to provide us with this information over the next a few months. Our (and your) curiosity will soon be satisfied!

This result opens a new era of physics with new possible discoveries likely to come.


For articles by Peter Higgs, Robert Brout, François Englert, John Ellis, Giovanni Ridolfi, Fabio Zwirner, Ignatios Antoniadis and other scientists, please visit: http://www.sciencedirect.com/science/journal/16310705/8/9

(*) Please read FAQ n. 2.

(**) For a recent study of the possible instability of the Higgs potential, see: http://arXiv.org/pdf/1205.6497.pdf

Interview by Antonella Del Rosso