https://doi.org/10.1140/epjc/s10052-015-3791-0
Regular Article - Theoretical Physics
Predictions of covariant chiral perturbation theory for nucleon polarisabilities and polarised Compton scattering
1
Institut für Kernphysik and PRISMA Cluster of Excellence, Johannes Gutenberg Universität Mainz, 55128, Mainz, Germany
2
Institute for Theoretical and Experimental Physics, 117218, Moscow, Russia
3
National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Moscow, Russia
4
Theoretical Physics Group, School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK
* e-mail: lensky@itep.ru
Received:
16
October
2015
Accepted:
10
November
2015
Published online:
19
December
2015
We update the predictions of the SU(2) baryon chiral perturbation theory for the dipole polarisabilities of the proton, 
fm
, and obtain the corresponding predictions for the quadrupole, dispersive, and spin polarisabilities: 
fm
, 
fm, and 
fm
. The results for the scalar polarisabilities are in significant disagreement with semi-empirical analyses based on dispersion relations; however, the results for the spin polarisabilities agree remarkably well. Results for proton Compton-scattering multipoles and polarised observables up to the Delta(1232) resonance region are presented too. The asymmetries 
and 
reproduce the experimental data from LEGS and MAMI. Results for 
agree with a recent sum rule evaluation in the forward kinematics. The asymmetry 
near the pion production threshold shows a large sensitivity to chiral dynamics, but no data is available for this observable. We also provide the predictions for the polarisabilities of the neutron, the numerical values being 
fm, 
fm, 
fm, and 
fm. The neutron dynamical polarisabilities and multipoles are examined too. We also discuss subtleties related to matching the dynamical and static polarisabilities.
© The Author(s), 2015
