Physicists from Northwestern, Harvard and Yale Universities (USA) conducted the ACME II experiment and measured with record accuracy the value of the electric dipole moment (EDM) of an electron - the difference between the material center of a particle and the charge center. It turned out to be equal to zero, which made it possible to reject the existence of some hypothetical particles proposed in the framework of New Physics. The discovery of these particles would help solve a number of paradoxes regarding the existence of the universe. The article of scientists was published in the journal Nature.
The properties of known elementary particles are described by the Standard Model, which cannot explain a number of physical phenomena (for example, the origin of mass, neutrino oscillations and the origin of dark mass). To solve this problem, scientists have put forward a number of hypothetical principles related to New Physics. According to one of them - supersymmetry - each known elementary particle corresponds to a superpartner with a heavier mass. For example, the partner of the electron, which is the fermion, is the selectron boson, and the partner of the gluon (which is the boson) is the gluino fermion. However, until now these hypotheses have not been confirmed experimentally.
According to the theory, the presence of hypothetical particles leads to the appearance of a nonzero EDM for the electron. However, the results of previous experiments have shown that if an electron has an EDM, then devices with ultra-high sensitivity are needed to detect it. The Standard Model predicts that the electron still has EDM due to violation of CP invariance, but it is too small to be distinguishable. The electric dipole moment arising in the theories of New Physics should be much larger, and the larger the particle mass, the less effect it should have on the EDM.
It is shown that a particle whose mass is equivalent to an energy of 1-100 teraelectron-volt (TeV) should induce an electric dipole moment in the range from 10 to the minus 27th power to 10 to the minus 30th power of elementary charges per centimeter (e * cm) … This is an order of magnitude less than the value that was available to experimenters before.
In the ACME II experiment, which was 10 times more sensitive than ACME I, physicists found no evidence of a nonzero EDM. This indicates that hypothetical CP-violating particles, if they exist, have such large masses (above 30 TeV) that they cannot be detected at the Large Hadron Collider at current collision energies.