Higgs Hedge: CERN Announces Definite Maybe

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Home / Higgs Hedge: CERN Announces Definite Maybe

Computer simulation of particle traces from an LHC collision in which a Higgs Boson is produced. (c) CERN. Image credit: Lucas Taylor

It’s on the radio.

It’s in the news.

On July 4, 2012, the long awaited CERN announcement declared a new particle has been found.

But is it the Higgs boson — the fundamental particle which gives other particles their mass? CERN physicists say they need more analysis to be sure.

The Higgs Theory

According to the so-called standard model of quantum mechanics, the fundamental particles which make up our universe include electrons, neutrinos, and quarks (which make up protons and neutrons).  But what gives these particles their mass? In 1964, three groups of physicists independently proposed an answer: the Higgs field, named after one of the researchers, English physicist Peter Higgs.

Scientists proposed that the Higgs field formed just after the big bang, and now permeates our entire universe. Its strength in empty space is not zero – it is as though the vacuum of space contains an invisible field of molasses affecting the movement of the basic building blocks of matter.

Per the Higgs Field theory, the more strongly a particle interacts with the Higgs field, the more massive it becomes. However, some particles, like photons (particles of light) do not interact with the Higgs field at all, so remain massless. As Reuters put it: “The Higgs theory explains how particles clumped together to form stars, planets and life itself. Without the Higgs field, the universe would have remained a formless soup of particles shooting around at the speed of light.”

Several years later, physicists Steven Weinberg predicted the existence of the “Higgs boson” — the messenger particle of the Higgs field. (Just as the photon is the messenger particle of the electromagnetic field.) And the hunt for this elusive particle was on.

It’s a Boson!

Unfortunately, the Standard Model of Quantum Mechanics does not predict the rest mass of the Higgs boson — and equivalently, per E = mc2, its rest energy. Plus, as CERN’s Atlas News explains: “The Higgs Boson is an unstable particle, living for only the tiniest fraction of a second before decaying (transforming) into other particles. So experiments can observe it only by measuring the products of its decay.” Just as a water wake on a lake tells us a motor-boat has passed, excesses of these residual particles tell us the Higgs boson has been there.

Candidate Higgs Decay to four muons recorded by ATLAS in 2012. Image courtesy CERN Atlas News.

Using this method, two independent CERN Large Hadron Collider experiment teams — ATLAS and CMS — arrived at very close to the same conclusion. A new particle has been discovered and it is a boson.  (A boson is a particle with integer spin, such as a photon which has a spin if 1. Spin is a measure of the angular momentum of a particle.)

Per the Geneva Press release:

“We observe in our data clear signs of a new particle, at the level of 5 sigma, in the mass region around 126 GeV (about 135 times the mass of a proton).” said ATLAS experiment spokesperson Fabiola Gianotti.

“The results are preliminary but the 5 sigma signal at around 125 GeV we’re seeing is dramatic. This is indeed a new particle. We know it must be a boson and it’s the heaviest boson ever found,” said CMS experiment spokesperson Joe Incandela.

This is exciting news. But is it the Higgs boson? Or, as CERN put it, “something more exotic?”

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