# What parameters determine the amount of Uehling potential and self-energy correction effects?

Uehling potential correction and electron self-energy correction are the two most important factors contributing to the lamb shift in the hydrogen atom, by "smearing" the wavefunction of the electron. What parameter(s) determine "how much" this smearing of the wavefunction is?

• You would have to mathematically define what you mean by “smearing” of a wavefunction. I would describe all wavefunctions as smeared even without any QED corrections. Apr 29 '19 at 1:44
• Electron self-energy correction and Uehling correction change the wavefunction of the electron with regard to the case we are not considering QED effects. I mean the amount of that change. You mentioned that these are the major contributors to the lamb shift. My question is, what determines how largely these QED effects affect the wavefunction of the electron, electrons velocity, strength of the electric field the electron is sensing, electric potential, or what? Apr 29 '19 at 1:48
• en.wikipedia.org/wiki/Lamb_shift has a derivation of the fluctuation in the position of the electron. Apr 29 '19 at 1:48
• The fine-structure constant is the relevant parameter which determines the fluctuation in the position compared with the Compton wavelength. Apr 29 '19 at 1:52
• As far as I know, the fine structure constant is always equal to 1/137, so the fluctuation in the position should be equal for all electrons in all atoms. Is this true? Apr 29 '19 at 1:58