Slashdot Mirror
Measurement Shows the Electron's Stubborn Roundness (scientificamerican.com)
OneHundredAndTen writes: A new article in Nature reports of a new, extremely precise measurement of the electric dipole moment of the electron. The conclusion is that, within the margin of error of the measurement, the electron remains a perfect sphere. This implies that supersymmetric theories keep running out of corners to hide, that another nail is driven into their coffin, and that string theory looks less and less compelling. By lighting up the molecules with lasers, "the scientists were able to interpret how other subatomic particles alter the distribution of an electron's charge," reports Scientific American. "The symmetrical roundness of the electrons suggested that unseen particles aren't big enough to skew electrons into squashed oblong shapes, or ovals. These findings once again confirm a long-standing physics theory, known as the Standard Model, which describes how particles and forces in the universe behave."
I do not think they are claiming anything of the sort. They are saying that, as alternative theories become less likely, there is more reason to believe the Standard Model could be correct.
The abstract:
"The standard model of particle physics accurately describes all particle physics measurements made so far in the laboratory. However, it is unable to answer many questions that arise from cosmological observations, such as the nature of dark matter and why matter dominates over antimatter throughout the Universe. Theories that contain particles and interactions beyond the standard model, such as models that incorporate supersymmetry, may explain these phenomena. Such particles appear in the vacuum and interact with common particles to modify their properties. For example, the existence of very massive particles whose interactions violate time-reversal symmetry, which could explain the cosmological matter–antimatter asymmetry, can give rise to an electric dipole moment along the spin axis of the electron. No electric dipole moments of fundamental particles have been observed. However, dipole moments only slightly smaller than the current experimental bounds have been predicted to arise from particles more massive than any known to exist. Here we present an improved experimental limit on the electric dipole moment of the electron, obtained by measuring the electron spin precession in a superposition of quantum states of electrons subjected to a huge intramolecular electric field. The sensitivity of our measurement is more than one order of magnitude better than any previous measurement. This result implies that a broad class of conjectured particles, if they exist and time-reversal symmetry is maximally violated, have masses that greatly exceed what can be measured directly at the Large Hadron Collider."
Bingo. You answered the apparent contradiction yourself.
Electrons are point-like particles -- meaning they're so small as to not have a well defined size if any. You describe the electron density for the orbitals of electrons -- which can be many shapes. That's more about the probability of where to find an electron in relation to the type of atom or the molecular bond between atoms.
This article is about the magnetic moment of the electron. So, if an electron were in a known position, this experiment shows that it doesn't matter from what direction in 3-D space another particle approaches this hypothetical electron, it will still get the exact same response. So, the field force-lines around the electron are perfectly spherical in strength.
This was important because electrons have a magnetic moment (like a bar magnet) that we call spin -- either spin up or spin down... which you're likely familiar with in chemistry as the rule that 2 electrons can share the same orbital as long as they are opposite spins. Some alternate theories propose that this means some parts of the electron are more charged than others or that the shape was more like a spinning charged ring instead of a sphere.
We've long known that nothing is actually spinning to create "spin." It's just a label for a quantum property that was somewhat useful as an analogy long ago. Yet, there remains this strange source of angular momentum. This experiment just confirmed that even though there is a magnetic dipole moment, that property doesn't mean the particle itself is distorted in order to express the property.
What's even weirder is that "spin" being a quantum property, is in a strange superposition state until measured and the spin axis can change depending upon the experiment.... with no intermediary direction for the spin. It's a binary choice -- spin up or spin down for any axis tested.... and seemingly random.
TL,DR -- this test just showed that the particle we call an electron is the same when approached from all angles - same charge, same interaction. So, it's "spherical" even though it's point-like. The probability distribution of an electron's location in atomic orbitals or molecular bonds is a different subject.
Now if only the Standard Model were an actual theory, instead of a list of empirical observations.
It is a theory that made testable predictions (like the Higgs boson) that were later proven to be correct via experiment. If that's not a theory then nothing is.