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The ATLAS will study the subatomic particle collisions at the world's most powerful atomic particle collider and, hopefully, will shed light on dark matter.


Supersymmetry particles - the pot of gold at the end of matter

by Marita Vera
Oct 14, 2009



About 80 percent of the mass in our Universe is currently invisible to us.

It is thought to be made of a mysterious hypothetical substance called dark matter. Scientists here hope to find more clues about it when the world's largest and most powerful particle accelerator, the Large Hadron Collider [LHC] in Switzerland, restarts in late November after nearly a year-long shutdown due to mechanical problems.

"In my opinion, the most exciting theory that could be proved is that of supersymmetry," said physicist Mark Oreglia. "If we can find supersymmetry particles it would explain a number of problems we have in physics, like dark matter."

Oreglia is a physicist at the Enrico Fermi Institute of the University of Chicago, and an investigator for ATLAS, one of the four large experiments that will study the subatomic particle collisions at the Swiss accelerator. The experiments partner scientists from around the world.  

Should operations go as planned, findings promise a cornucopia of new theories forwarding the knowledge of the scientific community and general understanding of the universe.

As Oreglia explains, matter - the stuff that has mass - is made up of two families of particles, building blocks called  quarks and leptons that in turn make up familiar particles such as protons and electrons. But that 80 percent of matter we can’t see does not behave like the quarks and leptons, so it must be something else. One possibility is that there is a new class, or family, of particles completely different from quarks and leptons. These are the theoretical supersymmetry particles.

The idea of supersymmetry, proposed over 30 years ago, theorizes the existence of partners (“superparticles”) to all known particles. The theory shook the physics community with a sort of a parallel universe of partner particles.  

Physicist John Schwarz, of the California Institute of Technology, was one of the pioneers who worked on the superstring theory of matter that led to the theory of supersymmetry. Superstring theory models all the particles and forces of nature as miniscule oscillating strings that are “supersymmetrical.” Schwarz's predictions about superparticles might soon become reality. 

"Supersymmetry ought to be discovered before too long.  And when that happens, it's going to be dramatic," he said in in Brian Greene's book on physics, "The Elegant Universe." 

Schwarz shares Oreglio’s goals, saying, “I think it would be great if supersymmetry particles were discovered at the LHC.”

No one has seen a supersymmetry particle because they would be very heavy, so heavy, in fact, that they have not been seen by the accelerator at the Fermlab near Chicago. It will take higher energy levels to create them and it is believed that the Swiss collider has enough energy to produce supersymmetric partners.

"Two big detectors are ready to take data now -- waiting to see particles emerging from LHC's first collisions" said Oreglia.  "Once things get running, we may get our very first collisions at low energy around Christmas. Around early in the New Year, the machine should be operating at fairly high intensity and that could yield exciting physics results in one year's time."

Oreglia said he hopes, like many others, to "interpret the data and come out with a new view of nature."