The Gerasimov-Drell-Hearn sum rule with nuclear targets

• Published in: The European physical journal. A, Hadrons and nuclei Vol. 59; no. 10
• Main Authors: Bass, Steven D., Pedroni, Paolo, Thomas, Andreas
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 23.10.2023
• Subjects: Hadrons; Heavy Ions; Nuclear Fusion; Nuclear Physics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Regular Article – Experimental Physics
• ISSN: 1434-601X; 1434-601X
• DOI: 10.1140/epja/s10050-023-01152-y

Hadron properties are modified when the hadron is embedded in a nuclear medium. Here we discuss the Gerasimov-Drell-Hearn, GDH, sum rule for polarised photoproduction from a polarised nucleon within a polarised nuclear target. Strong enhancement is expected with the suppression of the proton and nucleon resonance masses and enhancement of the proton’s anomalous magnetic moment in medium. This could be tested in polarised photoproduction experiments with interesting targets being polarised deuterons, 3 He, 6 Li and 7 Li. The largest contribution to the GDH sum rule comes from the Δ resonance excitation. In existing data with polarised deuterons and 3 He the Δ excitation is shifted to slightly lower energy when compared to model predictions where the Δ is treated with its free mass.