Talk:Electron electric dipole moment

How can you define the electric dipole moment of a charged particle?

The electron is a charged particle. What is the operational definition of the dipole moment of a charged particle? For a net-neutral distribution of charge the computed dipole moment is independent of the point about which one takes moments. For a distribution with a net charge, the moment depends on the point selected as the "center". If you take the charge centroid as the definition of the particle position, then the electric dipole moment about that point is zero by definition.

The definition in the article is similarly ambiguous. In an electric field, the charge itself gives rise to a position-dependent potential energy --- so changing "where" you say the particle is, changes a ${\bf {E}}\cdot {\bf {d}}$ contribution by an arbitrary amount.

I assume that particle physicsts actually define their "dipole moment" by some structure function in the matrix elements of the electro-weak current. Can anyone tell us which structure function it is?

Mike Stone (talk) 12:16, 20 April 2017 (UTC)

I added a section with the formal form-factor definition

Mike Stone (talk)