Electron's shapeliness throws a curve at supersymmetry

Dec 19, 2013
A "molecular eye" view of the vacuum chamber used for the measurement of the electron's EDM. Credit: B.R. O'Leary

A small band of particle-seeking scientists at Yale and Harvard has established a new benchmark for the electron's almost perfect roundness, raising doubts about certain theories that predict what lies beyond physics' reigning model of fundamental forces and particles, the Standard Model.

"We know the Standard Model does not encompass everything," said Yale physicist David DeMille, who with John Doyle and Gerald Gabrielse of Harvard leads the ACME collaboration, a team using a strikingly different method to detect some of the same types of sought by huge experiments at the Large Hadron Collider (LHC) in Europe. "Like our LHC colleagues, we're trying to see something in the lab that's different from what the Standard Model predicts."

ACME is looking for new particles of matter by measuring their effects on the shape of the electron, the negatively charged subatomic particle orbiting within every atom.

In research published Dec. 19 in Science Express, the team reported the most precise measurement to date of the electron's shape, improving it by a factor of more than 10 and showing the particle to be rounder than predicted by some extensions of the Standard Model, including some versions of Supersymmetry. This theory posits new types of particles that help account, for example, for dark matter, a mysterious substance estimated to make up most of the universe.

Researchers said they have shown that the electron's departure from spherical perfection—if it exists at all—must be smaller than predicted by many theories proposing particles the Standard Model doesn't account for. If the electron's shape is too round, many of these theories will be proven wrong, they said.

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Credit: ACME Collaboration

Many variants of Supersymmetry predict a less round shape for the electron than the ACME team found experimentally. If the particles predicted by those versions of Supersymmetry existed, they would have caused greater deformation of the electron, researchers said.

The ACME project looked for a particular deformation in the electron's shape known as an electric .

"You can picture the dipole moment as what would happen if you took a perfect sphere, shaved a thin layer off one hemisphere and laid it on top of the other side," said DeMille, who helped establish previous landmark limits in electron deformation. "The thicker the layer, the larger the dipole moment. Now imagine an electron blown up to the size of the earth. Our experiment would have been able to see a layer 10,000 times thinner than a human hair, moved from the southern to the northern hemisphere. But we didn't see it, and that rules out some theories."

The ACME researchers measured the dipole moment using electrons inside the polar molecule thorium monoxide. The molecule's properties amplify the electron's deformation and diminish the possibility of effects that could fool researchers into thinking they had seen a tiny deformation when none exists.

"It is amazing that some of these predicted would squeeze the electron into a kind of egg shape," said Harvard's Doyle. "Our experiment is telling us that this just doesn't happen at our level of sensitivity."

Gabrielse, also of Harvard, said: "It's unusual and satisfying that the exquisite precision achieved by our small team in a university lab probes the most fundamental building block of our universe at a sensitivity that complements what is being achieved by thousands at the world's largest accelerator."

Explore further: JILA team develops 'spinning trap' to measure electron roundness

More information: "Order of Magnitude Smaller Limit on the Electric Dipole Moment of the Electron," Science Express, 2013.

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User comments : 17

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Surly
5 / 5 (5) Dec 19, 2013
SUSY's really taken a beating in the last few months, hasn't it?
Shabs42
5 / 5 (4) Dec 20, 2013
I was just thinking this was at least the third article I've read on phys.org lately about evidence against supersymmetry.

SUSY's really taken a beating in the last few months, hasn't it?

Asimo1
5 / 5 (3) Dec 20, 2013
Yea.. It may be a problem for superstring theory, which is supersymmetry based, too.
thingumbobesquire
2 / 5 (3) Dec 20, 2013
It doesn't matter to adherents of the theory of everything they have an imaginary gazillion dimensional landscape where everything is possible by and by. Yea, lord, by and by. Hallelujah! And they now are winning millions of dollars in prizes for writing papers on this absurdity. What a racket.
jlewis
1 / 5 (1) Dec 20, 2013
If the electron was a loop superstring, but spinning at a VERY high rate, wouldn't that give it the appearence of being a small spherical object with no magnetic dipole? Imaging a ring spinning such that the center of the ring is also the center of rotation.

Then you could have resonances that match the complexity of the rotations.
cantdrive85
1.6 / 5 (7) Dec 20, 2013
Why does the electron and the sun share such baffling perfect roundness?
http://www.scienc...0801.htm

Probably due to the EM forces involved in confining the matter.
http://www.youtub...n3cOL690
Grallen
5 / 5 (3) Dec 20, 2013
@thingumbobesquire:
If no one tries to figure it out: no one will figure it out. And we and/or our descendants will die horrible deaths on our backwater mud ball that we never developed the technology to leave.

Please stop complaining that it takes millions of dollars to do science, because it DOES take millions of dollars to do science. And it needs to be done. And we do not figure out what is right unless we also figure out what is wrong.
shavera
5 / 5 (2) Dec 20, 2013
Yeah, right now, supersymmetry is taking a heavy beating. So it will be neat to see what comes up to fill in the cracks between what works now and what doesn't. There are still ways for supersymmetry to work, but it will be interesting to see if there's a reason why our universe *doesn't* have ss.
cantdrive85
3 / 5 (5) Dec 20, 2013

Why does the cantdrive think that the sun has perfect roundness to be baffled at? The google says it isn't perfect round. And while we are at the baffling stage of the conversation, how does the cantdrive know what shape the electron might have? I googled that one too, and still can't find anything about roundness, perfect or baffling.


Here's 269,000,000 results in .21 seconds...
https://www.googl...;start=0

Then let's read the first sentence of this article!
"A small band of particle-seeking scientists at Yale and Harvard has established a new benchmark for the electron's almost perfect roundness"

Sometimes the google isn't even necessary. What's also baffling is your apparent stupidity.
TheGhostofOtto1923
3 / 5 (2) Dec 20, 2013

Why does the cantdrive think that the sun has perfect roundness to be baffled at? The google says it isn't perfect round. And while we are at the baffling stage of the conversation, how does the cantdrive know what shape the electron might have? I googled that one too, and still can't find anything about roundness, perfect or baffling.


Here's 269,000,000 results in .21 seconds...
-And you didnt read any of them.

"Well-Rounded: Sun Stays Nearly Spherical, Even When It Freaks Out"

-As in 'nearly spherical'. As in 'not perfect'.
cantdrive85
2.3 / 5 (3) Dec 20, 2013
This from one of the linked articles;
"The sun is nearly the roundest object ever measured. If scaled to the size of a beach ball, it would be so round that the difference between the widest and narrow diameters would be much less than the width of a human hair."

So now were splitting hairs, I guess you guys are right. I'll change that to "near perfect roundness".
kochevnik
5 / 5 (4) Dec 20, 2013
From my readings electrons have no shape. The are point particles
TheGhostofOtto1923
1 / 5 (2) Dec 20, 2013
This from one of the linked articles;
"The sun is nearly the roundest object ever measured. If scaled to the size of a beach ball, it would be so round that the difference between the widest and narrow diameters would be much less than the width of a human hair."
Yah the Hubble mirror had that sort of imperfection and it cost millions of dollars to fix.
met a more fishes
1 / 5 (1) Dec 22, 2013
Did no one else notice all those articles, at least up to second page, were all from fall 2012 mostly mid August? And I didn't notice many news sources having multiple articles. Seems kind of strange, how many would show up if you searched instead for "shape of the sun".
met a more fishes
1 / 5 (1) Dec 22, 2013
Ok,i stopped being lazy and did some of that research i suggested. got allot of the articles, my take was that scientist found the sun to be more round and also more flat than expected. Their conclusion strikes me ass Occam razor-ish, the sun retains the same shape as all other major bodies in our solar system and the smoothness it's related to it being the largest.

davidivad
not rated yet Dec 22, 2013
I think that saying that the electron is round is misleading to the general public.
StarGazer2011
not rated yet Dec 26, 2013
Maybe a stupid question but measuring the roundness of the electron (implying that its a discrete spherical object) seems at odds with the idea that it exists in some kind of 'probability cloud' around the nucleus. Does it have different states or what? Can anyone elaborate?

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