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Is there experimental evidence checking to see if the positron has an electric dipole moment at rest? Or has an experiment measured it’s magnetic dipole moment at rest?

Qmechanic
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Enrique Mendez
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    I mean, there's not yet an experiment that measures the electric dipole moment of the electron: it's still an interesting open question of whether it has one or not. As for magnetic moment, the positron will have one just because it has spin and charge. Not sure if it's actually been measured, though, although I don't see why it couldn't be or hasn't been. – march Mar 13 '19 at 22:38
  • @march "just because it has spin and charge" isn't a sufficient reason for a particle to have an EDM - that requires a parity-breaking interaction. (See my answer linked by Anna below.) In the case of the electron and positron, that can be the weak force, or some beyond-the-SM new physics. It's not quuite accurate to say that it's an open question whether the electron had a dipole moment - no one seriously doubts that it has one, the question is just how big it is. – Emilio Pisanty Mar 14 '19 at 09:01

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The electron's magnetic dipole moment has been measured extremely accurately, as desribed here.

Attempts to detect an electric dipole moment of an electron have all failed, indicating that if electrons do have an electric dipole moment it must be extremely small.

The positron, according to all theory and experimental results to date, is just the same as an electron except that its charge is positive instead of negative. So it is pretty safe to assume that a positron's magnetic dipole moment is identical to that of an electron, and that its electric dipole moment is zero or extremely small.

S. McGrew
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  • @annav =( I know your name is easier to spell than mine, but still. – Emilio Pisanty Mar 14 '19 at 08:49
  • Note that it is extremely unlikely for the electron EDM to be exactly zero - that's not a possibility that's being seriously considered by anyone. The Standard Model has a clear prediction of a nonzero eEDM, it's just that it's too small to measure currently. If experiments do get to that level of sensitivity and rule out that prediction, then that would be as exciting a discovery (probably more exciting) as a value that's larger than the SM one. – Emilio Pisanty Mar 14 '19 at 08:56
  • a good relevant answer by @EmilioPisanti is here https://physics.stackexchange.com/questions/429390/can-the-center-of-charge-and-center-of-mass-of-an-electron-differ-in-quantum-mec – anna v Mar 14 '19 at 09:04