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