Several popular theories of what lies beyond the Higgs boson face ‘severe’ scrutiny

December 19, 2013

Several popular theories of what lies beyond the Higgs boson face ‘severe’ scrutiny

Scientists have made the most precise measurements ever of the shape of electrons.

According to a news release from Harvard University, Harvard and Yale scientists have made the most precise measurements ever of the shape of electrons and, as a result, have raised “severe” doubts about several popular theories of what lies beyond the Higgs boson.

“We are trying to glimpse in the lab any difference from what is predicted by the Standard Model, like what is being attempted at the LHC,” said John Doyle, Professor of Physics at Harvard, in a statement.

“It is unusual and satisfying that the exquisite precision achieved by our small team in its university lab probes the most fundamental building block of our universe at a sensitivity that compliments what is being achieved by thousands at the world’s largest accelerator,” added Gerald Gabrielse, the George Vasmer Leverett Professor of Physics at Harvard. “Given that the Standard Model is not able to explain how a universe of matter could come from a big bang that created essentially equal amounts of matter and antimatter the Standard Model cannot be the final word.”

To search for particles that might fall outside the Standard Model, the scientists precisely determine how particles effect on the shape of electrons.

Under the Standard Model electrons are anticipated to be nearly perfectly round, but most novel theories of what lies beyond the Standard Model also anticipate the electron to have a much bigger departure from a perfect roundness.

The team has recorded the most sensitive measurement to date of the electron’s deformation. Their findings show that the particle’s departure from spherical perfection, if its exists at all, must be smaller than anticipated in may theories that include new particles.

Supersymmetry proposes new types of particles that expand those in the Standard Model. It may help to account, for instance, for dark matter. It may also provide an explanation for why the Higgs particle’s mass turns out to have the value observed at the Large Hadron Collider. These are facts about the universe that cannot be explained by the Standard Model, according to scientists.

“It is amazing that some of these predicted supersymmetric particles would squeeze the electron into a kind of egg shape,” Doyle said. “Our experiment is telling us that this just doesn’t happen at our level of sensitivity,” noted Doyle.

To test for electron deformation, the scientists search for a specific deformation in the electron’s shape called an electric dipole moment.

“You can picture the dipole moment as what would happen if you took a perfect sphere, then shaved a thin layer off one hemisphere and laid it on top of the other side,” said David DeMille of Yale. “The thicker the layer, the larger the dipole moment.”

The scientists determined the electron’s electric dipole moment utilizing electrons inside the polar molecule thorium monoxide, which intensifies the deformation.

According to the scientists, the tests were more than ten times more sensitive than any earlier test for the effect.

“We are optimistic that we can probe ten times more deeply in the next several years,” added Gabrielse. “If so, the ACME experiment will remain a strong contender in the race to find the first particles that lie beyond the Higgs boson.”

The study’s findings are described in greater detail in the journal Science Express.


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