Strange Particle Created; May Rewrite How Matter's Made

Brian Handwerk
for National Geographic News
March 20, 2009
An unexpected new subatomic particle has been discovered in Illinois's Fermilab atom smasher, scientists announced this week.

The new particle may break all known rules for creating matter, say the researchers who created the oddity.

Y(4140)—as the new particle has been dubbed—couldn't have formed through either of the two known models for matter creation. Researchers aren't even sure what Y(4140) is made of.

It's long been accepted that six different "flavors" of particles called quarks combine to form larger subatomic particles.

In one method, a quark pairs with one of its opposites, an antiquark, to create a type of matter called a meson. In the second method, three quarks gather to form baryons, such as protons and neutrons.

(Related: "Bulk of Missing 'Normal' Matter Found in Cosmic Web.")

"The surprise about this new particle that we found is that it's not predicted by any of these rules," said Jacobo Konigsberg of the University of Florida.

"From what we know, if you tried to put a set of quarks or antiquarks together you couldn't build these particles."

Smash Hits

Particle physicists explore the origins of matter by smashing two streams of particles into each other at nearly the speed of light and sorting through the exotic, short-lived particles that are produced.

"The idea is that you collide protons and antiprotons in a very small point in space and release a lot of energy—equivalent to [the energy] the universe had at the very early stages of its birth," Konigsberg explained.

"Then nature creates whatever it can create," said the physicist, who co-authored a paper about the new particle submitted to the journal Physical Review Letters.

"The fun part is decoding the possibilities when you get very rare things out of that point of energy."

Y(4140) emerged as scientists sorted through the data from trillions of proton-antiproton collisions at the Department of Energy's Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois.

Whole New Class

The discovery is one of several recent finds that have physicists rethinking the rules for how matter is made.

"Apparently there are a lot more ways of putting things together than we thought," said Syracuse University physicist Sheldon Stone, who runs experiments based on data from the Large Hadron Collider in Europe.

"Y(4140) is part of this whole class of objects which people don't really understand," said Stone, who was not part of the Fermilab research team.

Other researchers will no doubt try to identify the particle in their own collision data, Stone said. There should be ample opportunities to confirm that Y(4140) is real, if rare, he added.

According to Fermilab's Rob Roser, Y(4140) was found only about 20 times in billions and billions of collisions.

But with plans to triple Fermilab's massive collision dataset over the next few years, more exciting discoveries should emerge.

"We should learn more about the properties of this particle," Roser said, "and we also hope to find many new things."

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