Are dark forces behind CDF’s bump?

By James Dacey at the APS April Meeting in Anaheim, California

Three weeks ago the CDF collaboration at Fermilab triggered a tidal wave of media coverage when it announced that it had discovered bump in its data that could not be explained by the Standard Model of particles physics. The unexplained signal was spotted in a study of W and Z boson pairs that are created when protons and antiprotons collide in Fermilab’s Tevatron collider.

Here at the APS April Meeting, I’ve just had a very interesting discussion with Fermilab theorist Dan Hooper, who speculates that the bump could be linked with dark matter. He believes that the excess of events, including a lepton and two jets, could be explained by the presence of a new gauge boson responsible for transmitting the force between dark matter and ordinary matter.

Hooper details his idea in a paper just uploaded to the arXiv preprint server in which he argues that the properties of the predicted boson would provide a natural explanation for the dark matter signals reported by the Cogent and DAMA/LIBRA collaborations.

“The most attractive explanation for the bump is the existence of a new fundamental force… if you’ll excuse the pun,” he said. “If this does turn out to be true, it would be absolutely incredible for physics.”

Earlier analysis by other researchers included speculation that the bump could be explained by a “technicolour” force. All seem to be in agreement, however, that the signal is not related to a Standard Model Higgs boson.

Hooper believes that whatever the bump turns out to be, its discovery has added significant weight to the case to extend the lifetime of the Tevatron. This iconic particle accelerator is due to close at the end of the US fiscal year (end of September), but several high-profile physicists have argued for an extension.