The Holy Grail of particle physics may already have been found.

Some call the Higgs boson the Holy Grail of particle physics. As the only undetected element of the field's theoretical masterpiece—the "standard model"—the Higgs guarantees a Nobel Prize for the experimenters who find it first. Now the European Union has spent an estimated $8 billion to build the world's largest particle accelerator, the large hadron collider, to finally track it down. 

So goes the reasoning, at least, of popular science writers. In the last month, The New Yorker, the New York Times, and the Boston Globe, among others, have run articles on the LHC, which will be capable of reaching energies seven times greater than any comparable device ever created. All of this coverage has focused on the Higgs.

But what if someone else has already found it?

A rumor flying around physics departments these last few weeks claims that physicists working at the Tevatron, an accelerator located outside of Chicago, have found something new.  Originally passed by word of mouth and private e-mail, the rumor made it into the blogosphere May 28, with an anonymous comment on the blog of a particle physicist living in Venice, Italy.  Since then, the rumor has spread. 

This isn't the first time a story like this has circulated. Until the LHC opens, the Tevatron remains the largest accelerator in the world. Among its most significant past discoveries is another standard-model particle, the top quark. And in 2009, it will shut its doors forever. Like the LHC, the Tevatron was built with the Higgs in mind, and as time runs out for America's biggest atom smasher, some nervy experimentalists have jumped the gun. Last summer, two Tevatron groups released some suggestive, but fruitless, graphs (PDF), just before the International Conference on High Energy Physics; in January, a new crop of rumors emerged, which were reported in the Economist and New Scientistin March. These other rumors have described "bumps": anomalies in the data that suggest a new particle but are too small for a definitive identification.

The current rumor, which comes in time for the summer conference circuit, may be different. It claims an experiment at the Tevatron has found a peak twice as high as the previous rumors' bumps. And unlike the other rumors, this one includes details: the new particle's mass, for instance, which fits within theoretical bounds on the standard model Higgs. Some versions include a decay chain, which describes what the new particle turned into as the experiment progressed, and which may be consistent with the standard model's predictions. 

Of course, the rumor also claims that no one associated with the experiment will confirm the new findings until they've had time to publish, likely within the next few weeks. And until they do, no one can be certain what the Tevatron has—or has not—found.

The hype surrounding the Higgs boson is well-deserved. The standard model, a unified view of physics first presented by John Iliopoulos in 1974, describes everything we know about the smallest building blocks of nature yet observed. It's the most accurate theory ever developed, in any field. And without the Higgs, it doesn't make much sense: Based purely on first principles, elementary particles should be massless. Some, like photons, do have zero mass; yet others are surprisingly heavy. Enter the Higgs, which would—in theory—interact with these latter particles to make the difference.