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Scientists Toast Nobel Prize for Higgs Discovery

Two physicists involved in long search for elusive subatomic particle

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October 8, 2013 | by Megan Fellman

EVANSTON, Ill. --- Northwestern University physicists applauded today’s news that the Nobel Prize in Physics was awarded to theorists Peter W. Higgs and Francois Englert “for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles.”

Two Northwestern professors, Mayda M. Velasco and Kristian A. Hahn, and their research groups played important roles in the search for the elusive fundamental particle, called the Higgs boson. Discovery of the Higgs, which gives elementary particles mass, was confirmed this year by the international ATLAS and CMS experiments at CERN’s Large Hadron Collider (LHC) in Europe.

Both Velasco and Hahn have been conducting research focused on decay modes of the Higgs at the LHC particle accelerator, where the new particle was first spotted early in 2012.

“We are thrilled with the recognition of the importance of the discovery of the Higgs boson,” said Velasco, a professor of physics and astronomy in the Weinberg College of Arts and Sciences.

“However, we should keep in mind that this is just the beginning,” she said. “In the next decade, we expect the LHC data will tell us if there is a connection between the Higgs boson and dark matter, or new extra dimensions in space-time that could explain why the gravitational force is so feeble compared to all other known forces: like electromagnetism, nuclear force and the weak force that produces the Higgs boson.”

In her work, Velasco specifically looks for the Higgs decaying to a Z-boson plus a photon.

“The relevance of this decay channel is that it is sensitive to ‘new’ particles -- like those due to new symmetries or extra dimensions  -- that we still don’t know anything about,” Velasco said.

Velasco and theorist Frank Petriello, an associate professor of physics and astronomy at Northwestern, are working members of the LHC Higgs Cross Section Working Group. The work of this group set a cornerstone for the experimental confirmation of a Higgs boson particle. It provided precise predictions of how the Higgs signal and corresponding backgrounds should look in the LHC environment.

Hahn, an assistant professor of physics and astronomy, is conducting research into one of the key decay modes of the Higgs boson -- the one that provides particularly important tests of its identity as *the* Higgs boson.

The search and discovery of the Higgs particle was nearly five decades long: The existence of the Higgs boson confirms the last remaining piece of the Standard Model of particle physics, a menu of the smallest particles and forces that make up the universe and how they interact.

Velasco and Michael H. Schmitt, a professor of physics and astronomy, co-lead Northwestern’s high-energy research group. Both have leadership roles at CMS, the general-purpose particle physics detector Northwestern is using at the Large Hadron Collider at CERN. Hahn also conducts his research at CMS.

More information on U.S. scientists’ role in the discovery of the Higgs boson is available online.