For physics postdoc, new evidence of things not seen

In Italy last week, Northeastern’s Joe Haley (third from left), joined here by an international team of physicists including François Englert (third from right) who helped predict the Higgs boson in the early ‘60s, presented new data about a theoretical particle essential to the standard model of physics. Courtesy photo.

For more than two decades, Fermilab in Batavia, Ill., housed the world’s largest particle accelerator — the Tevatron Collider — which allowed scientists to study the most elementary units of matter. Last September, Fermilab shut down the Tevatron forever. International hopes of understanding some of the most fundamental mysteries of particle physics began to shift to CERN in Geneva, Switzerland, home of the younger, more energetic Large Hadron Collider (LHC).

To many, Fermilab seemed like old news — until last week.

At the annual Moriond Electroweak Conference in Italy, Northeastern post-doctoral researcher Joe Haley and other Fermilab physicists announced that data collected at the Tevatron over the last 10 years show a new hint of the Higgs boson — a particle never observed, but nonetheless essential to the standard model of physics.

“There’s only so much information in [a single picture],” said Northeastern physics professor Darien Wood, who has worked at Fermilab and CERN since the 1980s. “But with a better magnifying glass you can get more information out of it.”

Between September and February, particle physics experts rolled up their sleeves and took out that better magnifying glass. They integrated data from dozens of research teams — including Northeastern’s — scanning them for evidence of the Higgs.

“You don’t see the Higgs directly,” said Wood. “You see the things it decays into.” Particle accelerators work by sending two beams of particles into head-on collisions at nearly the speed of light, according to physics professor Emanuela Barberis, who is also involved in the research. Various smaller particles result from these collisions; a series of detectors measure their masses. Accumulations at previously unobserved masses could be a sign of the Higgs.

Before graduating from Northeastern with his PhD last year, physicist Gabriel Facini looked at collisions that produced the particles known as neutrinos and “b-quarks.” Although among the hardest to detect, they are one of the most important channels for confirming Higgs activity, said Wood.

Since CERN and Fermilab look at different decay particles, LHC data cannot directly match Tevatron data; instead, the two datasets complement each other. In December, CERN released the first promising results about the Higgs. The new Fermilab data, “gives you more confidence that this thing that we might be seeing is the Higgs and has the properties that we expect,” said Wood.

“Physicists have been hunting for the Higgs boson since before I was born, so I feel incredibly lucky to be on the front lines now that we are finally closing in,” said Haley, who will give a physics colloquium talk, “Closing in on the Higgs Boson,” Tuesday at 11:15 a.m. in 114 Dana. “Within the next year, the Higgs boson will either be found or completely ruled out and to be part of this historic event is truly amazing.”