A hint of Higgs

Tue 13th December 2011

It has been over 40 years since it was first suggested but today after less than 4 years of running, the LHC experiments, ATLAS and CMS were able to announce that they have evidence for the Higgs Boson, but not enough to announce its discovery. They hope to be able to make the full announcement within a year, but none of this work would be possible without the computing resources provided by GridPP and its international partners.

In 1964 three ground breaking papers were published in Physical Review Letters that are widely recognized as milestones in modern physics and gave birth to the theory of the Higgs Boson. Currently it is the missing piece of the Standard Model, a theory that explains how the building blocks of the universe interact and behave. Put very simply without the Higgs there is no way of explaining how anything has mass, but that is not the whole story. Without the Higgs we simply don’t know how the universe works. The announcement today is one step closer to finishing the puzzle. “The results are tantalising, but not yet conclusive.” says Roger Jones, head of ATLAS Computing UK “The full picture will be known by next Summer, and accelerator, detectors and computing around the world will be working hard to add even more data to settle the issue until then.” Simulated production of a Higgs event in ATLAS. This track is an example of simulated data modelled for the ATLAS detector
Simulated production of a Higgs event in ATLAS.
Peter Higgs Visiting CMS
Peter Higgs Visiting the CMS expriment
Named after Prof. Peter Higgs of the University of Edinburgh, the eponymous boson has been searched for in numerous experiments including the Tevatron, which just recently finished running and the LHC’s predecessor at CERN, LEP. There have even been other experiments that have operated at the right energy level with the possibility of creating the Higgs. The difference with the LHC? The volume of data. The experiment is simply running with enough power that if the Higgs exists it is creating it in a far greater abundance than any other experiment. And this is important when you work with statistics, there is no single eureka moment, but there are eureka plots.

The scientists looking for the Higgs know what it could look like, and they have looked for how they expect the Higgs to interact with the detectors. This is where the grid comes in. The UK has a leading involvement in ATLAS and CMS but also is one of the largest resource providers for the LHC Computing Grid. As Roger explains “The fact we can present sophisticated results based on the 1000s of terabytes of data that were collected up to only three weeks ago is an astonishing tribute to the power of our grid computing systems.” Using the grid to analyse the collisions at CERN resulted in a peak in the data at around 125GeV. This is a result that agrees with theory and suggests that the Higgs is about 120 times heavier than a proton. While the hint is currently no more than a spike on a graph of data points, more importantly it is a spike on two independent graphs from different experiments that give physicists hope that with more data they will announce the discovery of the Higgs in 2012.


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