https://doi.org/10.1140/epjc/s10052-014-2852-0
Regular Article - Theoretical Physics
Chiral perturbation theory of muonic-hydrogen Lamb shift: polarizability contribution
1
Cluster of Excellence PRISMA Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, 55099, Germany
2
Theoretical Physics Group, School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK
3
Institute for Theoretical and Experimental Physics, Bol’shaya Cheremushkinskaya 25, 117218 , Moscow, Russia
* e-mail: alarcon@kph.uni-mainz.de
Received:
6
December
2013
Accepted:
9
April
2014
Published online:
29
April
2014
The proton polarizability effect in the muonic-hydrogen Lamb shift comes out as a prediction of baryon chiral perturbation theory at leading order and our calculation yields ΔE(pol)(2P-2S) = 8-1+3 µeV. This result is consistent with most of evaluations based on dispersive sum rules, but it is about a factor of 2 smaller than the recent result obtained in heavy-baryon chiral perturbation theory. We also find that the effect of Δ(1232)-resonance excitation on the Lamb shift is suppressed, as is the entire contribution of the magnetic polarizability; the electric polarizability dominates. Our results reaffirm the point of view that the proton structure effects, beyond the charge radius, are too small to resolve the ‘proton radius puzzle’.
© The Author(s), 2014
