Speaker
Dr
Jan (for the COMPASS collaboration) Friedrich
(CERN / TU Munich)
Description
With the COMPASS experiment at CERN, pion-photon reactions are investigated
via the Primakoff effect, implying that high-energetic pions react with the
quasi-real photon field surrounding the target nuclei.
The production of a single hard photon in such a pion scattering,
at lowest momentum transfer to the nucleus, is related to pion Compton
scattering. From the measured cross-section shape,
the pion polarisability is determined. The COMPASS measurement is in
contradiction to the earlier dedicated measurements, and rather in agreement
with the theoretical expectation from chiral perturbation theory.
In the same experimental data taking, reactions with neutral and charged
pions in the final state are measured and analyzed. At low energy in the
pion-photon centre-of-momentum system, these reactions are governed by
chiral dynamics and contain information relevant for chiral perturbation
theory. At higher energies, resonances are produced and their
radiative coupling is investigated.
Author
Dr
Jan (for the COMPASS collaboration) Friedrich
(CERN / TU Munich)
