Fermilab fails to confirm existence of new particle

Posted by Kate Taylor

Physicists at the US Department of Energy's Fermi National Accelerator Laboratory say they've been unable to confirm the existence of a new particle indicated by Fermilab experiments in April.

The Fermilab team collided protons and antiprotons at energies between 120 billion and 160 billion electron volts, and found an excess in the jets of particles produced. This could be explained, they said, by a new particle similar to the long-predicted Higgs boson, but heavier.
 
But the DZero team at the lab says it's looked at the data independently, following the same analysis procedure, and can't see the excess found by the original team, Collider Detector at Fermilab (CDF).

"Our data for collisions that produce a W boson plus two jets are in agreement with the predictions from the Standard Model," says DZero spokesperson Dmitri Denisov.

"We have looked among two hundred trillion particle collisions, and we don’t see the excess reported by CDF."

The DZero team says the red peak below 100 GeV/c2 is a well-known Standard Model feature of the decays of W and Z bosons. Its data shows no excess around 145 GeV/c2.

Over the last 10 years, CDF and DZero have published more than 500 measurements of particle physics processes using two different particle detectors and independent analysis tools.

Today's findings represent one of the one-in-a-hundred times that the two results fail to agree.

"This is exactly how science works," says DZero spokesperson Stefan SÓ§ldner-Rembold. "Independent verification of any new observation is the key principle of scientific research. At the Tevatron, we have two experiments that, by design, can check each other."

Now, of course, the physicists need to work out why the results were so different. Fermilab's planning to create a task force for this, consisting of members from both experiments and theorists Estia Eichten and Keith Ellis.