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Scientists more confident of Higgs

A view of the heart of the Atlas detector. ATLAS Experiment © 2013 CERN.

A view of the heart of the Atlas detector. ATLAS Experiment © 2013 CERN.

The European Organisation for Nuclear Research (CERN) has announced that scientists have analysed more data that indicates a recently discovered particle is increasingly looking like the elusive Higgs boson.

Last July, scientists said two Switzerland-based research projects had discovered a Higgs-like particle. The July announcement came in a progress report from the Large Hadron Collider (LHC), the £2.6 billion “Big Bang” particle accelerator at the centre of the hunt for the Higgs boson. The LHC has been dubbed the world's largest experiment and is housed at CERN, in Switzerland.

At the Moriond conference yesterday, the Atlas and CMS collaborations at the LHC presented preliminary new results. Having analysed two-and-a-half times more data than was available for the discovery announcement in July, they find that the new particle is looking more and more like a Higgs boson, the particle linked to the mechanism that gives mass to elementary particles.

The Higgs particle – or boson – is named after Peter Higgs, who was one of six authors who theorised about the existence of the particle in the 1960s. It is commonly called the “God Particle”, after the title of Nobel physicist Leon Lederman's “The God Particle: If the Universe Is the Answer, What Is the Question?” according to Wikipedia.

CERN says in a statement that it remains an open question; however, whether this is the Higgs boson of the Standard Model of particle physics, or possibly the lightest of several bosons predicted in some theories that go beyond the Standard Model, “finding the answer to this question will take time”.

The Higgs particle is the missing piece of the Standard Model of Physics, which is a set of rules that outline the fundamental building blocks of the universe, such as protons, electrons and atoms.

Significant step

University of Johannesburg professor Simon Connell, from the Department of Physics, explains that even if the particle is not Higgs, it is definitely a new particle and is “the most significant achievement in physics in a century”.

Connell says the discovery will power physics for years to come. He explains that abstract physics developments, like the laser, have come into everyday use, and the boson will lead to some amazing changes in everyday life.

CERN says whether the particle is the Higgs boson is demonstrated by how it interacts with other particles, and its quantum properties. For example, a Higgs boson is postulated to have no spin, and in the Standard Model, its parity – a measure of how its mirror image behaves – should be positive.

“CMS and Atlas have compared a number of options for the spin-parity of this particle, and these all prefer no spin and positive parity. This, coupled with the measured interactions of the new particle with other particles, strongly indicates it is a Higgs boson,” says CERN.

CMS spokesman Joe Incandela adds that the “preliminary results with the full 2012 data set are magnificent and to me it is clear that we are dealing with a Higgs boson, though we still have a long way to go to know what kind of Higgs boson it is”.

"The beautiful new results represent a huge effort by many dedicated people. They point to the new particle having the spin-parity of a Higgs boson as in the Standard Model. We are now well started on the measurement programme in the Higgs sector," says Atlas spokesman Dave Charlton.

To determine if this is the Standard Model Higgs boson, the collaborations must, for example, measure precisely the rate at which the boson decays into other particles and compare the results to the predictions. The detection of the boson is a very rare event – it takes around a trillion proton-proton collisions for each observed event. To characterise all of the decay modes will require much more data from the LHC.

Connell says the accelerator is set to be upgraded and will be able to produce the particle a hundred times faster and, as more data is collected, the particle’s properties will be pinned down. He explains that the Standard Model cannot answer many questions about the particle, and new physics will have to be developed to explain dark matter and dark energy.

Scientists will have to turn to nature to decide how to go forward, as the boson is diverging from the Standard Model, says Connell.

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