News

Higgs boson announcement an historic day for Physics


5 July 2012

Evidence for the existence of a new sub-atomic particle resembling the elusive and long-sought-after Higgs boson was announced last night in a pair of seminars given at the European Organisation for Nuclear Research, CERN.

The ATLAS detector at the Large Hadron Collider.
The ATLAS detector at the Large Hadron Collider.

"The Higgs boson has been sought for decades, and to think that we have seen something which looks very much like it is exciting," said Associate Professor Kevin Varvell, from the University of Sydney's School of Physics, which is part of the worldwide scientific effort to prove Higgs boson's existence.

"This announcement suggests that we are on the right track in our quest to gain a deeper understanding of the workings of the universe."

Thirteen University of Sydney staff and students are currently involved in the effort being conducted at CERN. Their input, combined with that of hundreds of other scientists, contributed to the announcement.

"This is a pivotal moment for science, as could be seen from the reactions of the physicists present. There was pride that such large and technologically difficult projects are bearing fruit, and maybe some relief as well."

Associate Professor Varvell is Director of the University of Sydney node of the ARC Centre of Excellence for Particle Physics at the Terascale (terascale refers to a scale of a factor of 10 to the power of 12 in electron volts, a unit used to measure energy).

The Higgs boson is named after British physicist Peter Higgs, who suggested in 1964 that a field in some respects similar to an electromagnetic field might be what gives particles their mass.

In this scenario particles acquire mass by interacting with the Higgs field, and directly observing the related Higgs boson particle in experiments would be the evidence that the Higgs field exists.

"The announcement made last night is the result of experiments done by teams of scientists operating two detectors - ATLAS and CMS - at the world's biggest atom smasher or particle collider, the Large Hadron Collider."

Australia helped design and build the 7000-tonne ATLAS detector that, along with the CMS detector, analyses the myriad of particles produced in the 40 million or so collisions a second.

"Our group here at the University of Sydney works on the ATLAS experiment at the Large Hadron Collider, making us part of an international collaboration of physicists around the world collecting and analysing the data from ATLAS," said Associate Professor Varvell.

"Higgs bosons are predicted to be very short lived and able to decay in many different ways, which means that we observed the particles they are predicted to decay into, rather than the Higgs bosons themselves."

"This is just the beginning in terms of what needs to be done to fully understand the properties of this new particle. We do not know yet whether it is indeed the Higgs boson as predicted by our Standard Model of Particle Physics, or something even more exotic and exciting."

The best way to answer this, apart from doing a lot more detailed and painstaking work, is to collect many more collisions, and this will now be the goal of the two experiments for the rest of 2012 and into the future.

"Our own group's work within ATLAS includes searching for evidence for theories such as those that come under the banner of supersymmetry," Associate Professor Varvell said.

Associate Professor Kevin Varvell
Associate Professor Kevin Varvell

"We know that the Standard Model developed over the past century to explain the building blocks of matter, even with Higgs on board, cannot be considered the ultimate theory of nature. There are models which go beyond it including those which even predict extra dimensions of space."

"Supersymmetry, for example, extends the Standard Model to fix some of its shortcomings, at the same time predicting many new particles which we can search for, including extra Higgs bosons and candidates for the dark matter which makes up a significant fraction of the universe."

Associate Professor Varvell and 15 other researchers in his team from the University of Sydney are participating in the International Conference on High Energy Physics in Melbourne, where the historic announcement was broadcast live from Geneva as a curtain-raiser to the conference.


Contact: Verity Leatherdale

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