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Higgs boson 'seen' at the LHC

A candidate for a VBF Higgs to Gamma Gamma Decay as seen in the CMS Detector [enlarge]

The announcement is the first step towards a landmark discovery in modern physics but it’s not a categorical declaration of the Higgs' existence. The conclusions would not have been possible without the global computing grid that the European Grid Infrastructure is a partner of.

The Higgs boson is the elementary particle required by the Standard Model, particle physics’ “theory of everything”, which works perfectly as long as the fundamental particles have no mass. In practice, not only do they have mass but also the mechanism that gives them mass was unknown. Then in the 1960s a number of physicists, including Peter Higgs, postulated a field that would permeate space, interacting with particles and giving them mass.

In physics every field has a 'carrier' particle, called a boson. For the 'Higgs' field to exist it needs a 'Higgs' boson and so the hunt was on to find evidence of, what would turn out to be, a very elusive particle.
   
Particle physics relies on two things: mathematics and particle accelerators. The first is where it all begins, attempting to explain how the world works through understanding the underlying maths. The second is the fun bit, researchers accelerate particles to high speeds and collide them with each other or against a target. The current state-of-the-art accelerator is the LHC, a 27km ring buried under the French/Swiss border accelerating protons to near the speed of light and colliding them. The LHC’s collisions recreate the conditions of the early universe, produce particles that we don’t see “in the wild” and help explain how the universe works. One of the particles it was hoped the LHC would create was the Higgs boson.

The LHC is based at the European Organization for Nuclear Research (CERN) and is not the first accelerator that hoped to spot the Higgs boson. Two of the most important were the Tevatron in the United States of America and LEP (the LHC’s predecessor at CERN). But while neither proved the existence of the boson they were able to set a lower limit on its size and energy level, narrowing down the search a little. With these lower energies ruled out it was hoped that the LHC, at least 8 times more powerful than the previous machines, would be where the Higgs boson would be first seen.

Alongside the massive engineering and energy advantage the LHC has over previous experiments, there is also the edge given by grid computing. With over 200,000 computers connected worldwide, the grid provides 24/7 access to the computational resources needed to understand the data deluge coming from the experiment. This means that researchers can process large datasets and extract the meaning from the collisions (600 million every second) being produced at CERN. All of the speakers at the announcemnet mentioned that the grid was an important component of the successes so far.

Dr Wahid Bhimj from The University of Edinburgh works both on the grid and on Higgs searches "We're all beside ourselves with excitement." he explains "Nature is unveiling a new particle in front of our eyes and the fact its looking consistent with the predictions of the Higgs is a beautiful verification of our understanding of the universe."

This announcement is not the end of the story for either the LHC or the grid. There are many more exciting areas of research that use the world’s largest machine including studying the top quark, as talked about in the 3rd “Stories from the grid” episode. And the grid is now a major tool for researchers across the globe working on disciplines as diverse as the humanities and computational chemistry.