https://doi.org/10.1140/epjc/s10052-017-4652-9
Regular Article - Theoretical Physics
Generalized polarizabilities of the nucleon in baryon chiral perturbation theory
1
Institut für Kernphysik, Cluster of Excellence PRISMA, Johannes Gutenberg Universität Mainz, 55128, Mainz, Germany
2
Institute for Theoretical and Experimental Physics, Moscow, 117218, Russia
3
National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow, 115409, Russia
* e-mail: lensky@itep.ru
Received:
9
January
2017
Accepted:
26
January
2017
Published online:
21
February
2017
The nucleon generalized polarizabilities (GPs), probed in virtual Compton scattering (VCS), describe the spatial distribution of the polarization density in a nucleon. They are accessed experimentally via the process of electron–proton bremsstrahlung (
) at electron-beam facilities, such as MIT-Bates, CEBAF (Jefferson Lab), and MAMI (Mainz). We present the calculation of the nucleon GPs and VCS observables at next-to-leading order in baryon chiral perturbation theory (B
PT), and confront the results with the empirical information. At this order our results are predictions, in the sense that all the parameters are well known from elsewhere. Within the relatively large uncertainties of our calculation we find good agreement with the experimental observations of VCS and the empirical extractions of the GPs. We find large discrepancies with previous chiral calculations – all done in heavy-baryon PT (HBPT) – and discuss the differences between BPT and HBPT responsible for these discrepancies.
© The Author(s), 2017
