Dr. Konigsberg, of the rival team, said they had their own analysis of their own b-quark measurements underway. He compared the rumor to a game of telephone that “starts one way, ends up the other.”

Dr. Dorigo said, “Right now there is nothing to build a story around.” Things could heat up again at conferences this summer in Karlsruhe, Germany, and Daegu, South Korea, where particle physics results are traditionally presented — or never.

The official silence did not stop speculation. If it is a Higgs, theorists say, it is probably not the one prescribed by the Standard Model, which would not be produced plentifully enough to be seen yet.

The leading alternative is that it would be one of five Higgs bosons predicted by a theory called supersymmetry, which theorists have been yearning for as the next step toward a more all-embracing, unified theory of nature. One bonus of supersymmetry is that it predicts the existence of more, yet undiscovered elementary particles, one of which might be the mysterious dark matter that binds galaxies together in the universe. All this would fall into the lap of the Large Hadron Collider scientists, if it exists, which is one reason the CERN physicists will be happy no matter what the outcome.

But if that is the case, the Tevatron should have already seen it, physicists said.

“If it’s real, it’s quite a weird object,” said Dr. Lykken, who had been discussing possible theoretical models with his Higgs-savvy colleagues just in case the anomaly does not go away. It would be hard to reconcile this result with all the data already collected by Fermilab and the L.E.P. at the European laboratory, he explained.

“I don’t know if we pinned down nature, or if nature has pinned us down, but there are many corners you can’t get into anymore,” Dr. Lykken said.

Dr. Weinberg, who acknowledged his rooting interest in the Higgs discovery, as the particle is at the center of Nobel Prize work, said he had heard the sighting rumor but did not know what to make of it. “I’m more patient now,” he said.