classical radius of nucleons and quarks

[relativityfan]

hi,

how do you calculate the classical radius of nucleons or quarks? do you include only the electrostatic potential energy or also some nuclear potential energy?. i have read many times that the classical radius of nucleons is lower than the classical radius of the electron, is it right?

thank you for your reply!

[Meir Achuz]

The "classical radius", usually defined as e^2//mc^2, has no physical significance.
It would be much smaller for a nucleon than an electron, but the physical radius of a
nucleon is almost 1 fm, while the electron physical radius is probably 0.

[tom.stoer]

For nucleons one can measure form factors (and structure functions); form factors are something like the Fourier transform of the corresponding density (charge, current, ...) so one can measure the radius indirectly via the charge, current, ... distributions

[relativityfan]

The "classical radius", usually defined as e^2//mc^2, has no physical significance.
It would be much smaller for a nucleon than an electron, but the physical radius of a
nucleon is almost 1 fm, while the electron physical radius is probably 0.

thank you, and how does it compare with the photon?

[Meir Achuz]

A photon is considered a point particle.