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Studying time-like electromagnetic baryonic transitions with HADES in pion induced reactions
- Source :
- EPJ Web Conf., 12th International Workshop on the Physics of Excited Nucleons, 12th International Workshop on the Physics of Excited Nucleons, Jun 2019, Bonn, Germany. pp.01012, ⟨10.1051/epjconf/202024101012⟩, EPJ Web of Conferences, Vol 241, p 01012 (2020)
- Publication Year :
- 2019
- Publisher :
- HAL CCSD, 2019.
-
Abstract
- A dedicated programme aiming at studying electromagnetic baryonic transitions in the time-like region has started at GSI using the pion beam and the High Acceptance Di-Electron Spectrometer (HADES) set-up. A pioneering experiment has been carried out in the second resonance region, at a center-of-mass energy of 1.49 GeV, using carbon and polyethylene targets, allowing for an analysis of the inclusivee+e-production and of the exclusive quasi-freeπ-p→ne+e-reaction, in complement to hadronic channels. Predictions for the Dalitz decay of N(1520) and N(1535) based on real photon couplings strongly underestimate thee+e-yield at invariant masses larger than 300 MeV/c2, which signals effects of time-like baryon transition form factors, in qualitative agreement with the Vector Dominance Models (VDM). A quantitative description of the observede+e-yield is achieved by taking into account the contribution from off-shellρs. The latter was provided by the preliminary results of a Bonn-Gatchina Partial Wave Analysis of the two-pion production channels, which were measured simultaneously in our experiment. A good agreement is also obtained using a covariant model for the time-like electromagnetic form factors for the N-N(1520) transition. The angular distributions for thee+e-production contain additional selective information on the spin structure of the different transitions. The measurements with the pion beam will be extended in future in the third resonance region. Hyperon Dalitz decay studies in proton induced reactions are also foreseen.
- Subjects :
- Photon
Proton
electron: yield
QC1-999
Partial wave analysis
Hadron
Nuclear Theory
[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
01 natural sciences
Resonance (particle physics)
Nuclear physics
Pion
photon: coupling
two-pion
0103 physical sciences
angular distribution
pi: beam
010306 general physics
Nuclear Experiment
Physics
form factor: transition
010308 nuclear & particles physics
N(1535)
Hyperon
electron: production
partial wave analysis
form factor: electromagnetic
Baryon
model: vector dominance
HADES
N(1520): decay
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- EPJ Web Conf., 12th International Workshop on the Physics of Excited Nucleons, 12th International Workshop on the Physics of Excited Nucleons, Jun 2019, Bonn, Germany. pp.01012, ⟨10.1051/epjconf/202024101012⟩, EPJ Web of Conferences, Vol 241, p 01012 (2020)
- Accession number :
- edsair.doi.dedup.....d5e1180a0badb2c0986fea601ad6a8b7
- Full Text :
- https://doi.org/10.1051/epjconf/202024101012⟩