Measurement of polarization observables T , P , and H in π 0 and η photoproduction off quasi-free nucleons.
Eur Phys J A Hadron Nucl
; 59(10): 232, 2023.
Article
in En
| MEDLINE
| ID: mdl-37860634
ABSTRACT
The target asymmetry T, recoil asymmetry P, and beam-target double polarization observable H were determined in exclusive π0 and η photoproduction off quasi-free protons and, for the first time, off quasi-free neutrons. The experiment was performed at the electron stretcher accelerator ELSA in Bonn, Germany, with the Crystal Barrel/TAPS detector setup, using a linearly polarized photon beam and a transversely polarized deuterated butanol target. Effects from the Fermi motion of the nucleons within deuterium were removed by a full kinematic reconstruction of the final state invariant mass. A comparison of the data obtained on the proton and on the neutron provides new insight into the isospin structure of the electromagnetic excitation of the nucleon. Earlier measurements of polarization observables in the γpâπ0p and γpâηp reactions are confirmed. The data obtained on the neutron are of particular relevance for clarifying the origin of the narrow structure in the ηn system at W=1.68GeV. A comparison with recent partial wave analyses favors the interpretation of this structure as arising from interference of the S11(1535) and S11(1650) resonances within the S11-partial wave.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Eur Phys J A Hadron Nucl
Year:
2023
Document type:
Article
Affiliation country:
Suiza