PoS - Proceedings of Science
Volume 375 - 14th International Symposium on Radiative Corrections (RADCOR2019) - Higher-Loop
The four-loop slope of the Dirac form factor
S. Laporta
Full text: pdf
Pre-published on: December 19, 2019
Published on: February 18, 2020
Abstract
We have evaluated with 1100 digits of precision the 4-loop contribution to the slope of the Dirac form factor in QED. The value is
$$ m^2 F_1^{(4)'}(0) =
0.886545673946443145836821730610315359390424032660064745{\ldots} \left(\frac{\alpha}{\pi}\right)^4 \ . $$
We have also obtained a semi-analytical fit to the numerical value. The expression contains harmonic polylogarithms of argument $e^{\frac{i\pi}{3}}$, $e^{\frac{2i\pi}{3}}$, $e^{\frac{i\pi}{2}}$, one-dimensional integrals of products of complete elliptic integrals and six finite parts of master integrals, evaluated up to 4800 digits. We show the correction to the energy levels of the hydrogen atom due to the slope.
DOI: https://doi.org/10.22323/1.375.0016
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