Physicists Just Generated a Particle That Acts as Its Own Antiparticle

Re:Physicists Just Generated a Particle That Acts as Its Own... by gus_massa on Monday July 24, 2017 @07:22PM (#14843652)

The gyromagnetic ration of a truly elementary particle is g=2. With the current theories, a electron has a cloud of virtual particles, but no internal structure. With this assumptions the theoretical value is approximately g=2+2.alfa/2pi+...~=2+1/(137*pi). The experimental value of the g of the electron agree with the theoretical value up to 14 digits, so it's a very good hint that the electron is really an elementary particle.

Obviously there can be future theory were the electron has internal structure, but it will be a breakthrough, not a small fix.

The theoretical and experimental value of g for a muon almost agree, but only 10 digits. So there is a small chance of something interesting there. But IIRC most people think that it may be a new particle in the cloud of virtual particles, not an internal structure of muons.

Protons and neutrons have internal structure, a lot of internal structure, so the value of g is a difficult to calculate number that is not 2. In particular, g=+5.6 and g=-3.8.

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Re:Physicists Just Generated a Particle That Acts as Its Own... by jessriedel on Monday July 24, 2017 @10:56PM (#14844756)

This is just a way of saying that we have probed the electron for internal structure to a significantly more precise level than the level necessary to reveal the known internal structure of nucleons. But it's just an upper bound. For all we know, the next accelerator (if there is one) could reveal composite structure just below the bound.

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