Not everyone is impressed with the new findings. The data are
"unconvincing," says Matt Strassler, a theoretical physicist at Rutgers University who was visiting CERN for the occasion. "I was a little disappointed," he adds, that the results did not live up to the expectations and the rumors—some called it a "Higgsteria"—that had circulated in the run-up to the announcement. On the other hand, he grants, no one expected to have a discovery at this stage—the experiments have not yet amassed enough data.
Vivek Sharma, Higgs search coordinator at the CMS collaboration, agrees that the two experiments have a small discrepancy on what the supposed Higgs mass would be, and that tantalizing hints of new physics from other experiments have often turned out to be statistical anomalies. "People should curb their enthusiasm," he cautions.
Joe Lykken, a theoretical physicist at Fermi National Accelerator Laboratory in Batavia, Ill., who is a member of the CMS collaboration, is more optimistic about the discrepancy. "Even though we are only seeing hints of the Higgs boson, it is encouraging that the ATLAS and CMS hints seem to be consistent with each other," he says.
A Higgs with a mass of 125 GeV would fit with a hypothesized extension of the Standard Model called supersymmetry, which posits that every known particle has a heavier, as-yet-undiscovered partner. "The low-mass Higgs is not so bad for supersymmetry, to say it diplomatically," CERN's Heuer said.
The LHC first fired up in September 2008, but within a week it was crippled by a serious accident that put it out of order for more than a year. "It was a big setback," says Lyn Evans, a CERN accelerator physicist who oversaw the construction and commissioning of the LHC from 1994 until his retirement a year ago. After repairs, however, the machine restarted in 2009 and has delivered more collisions than predicted, enabling the ATLAS and CMS collaborations to amass data five times faster than expected.
As recently as a year ago, one would not have thought that the LHC would make so much progress in its Higgs search by the end of 2011, observes Dmitri Denisov, spokesperson for the DZero experiment, one of the detectors at Fermilab's recently retired Tevatron collider. "It performed better than anyone expected," Denisov says.
If the Higgs really exists, it will answer the long-standing question of how matter gets its mass. It will also reveal the nature of the connection between two fundamental forces, the weak nuclear force and the electromagnetic force—a relationship termed the electroweak interaction. The two forces were unified for the first instants of our universe, but now they behave differently. Weinberg says the new results suggest that "it should be possible to reach a definite decision about whether this is the particle associated with the breakdown of the symmetries of the electroweak theory. I'll bet that it is."