The Gerasimov-Drell-Hearn sum-rule with nuclear targets

Abstract

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 $\Delta$ resonance excitation. In existing data with polarised deuterons and ${}^3$He the $\Delta$ excitation is shifted to slightly lower energy when compared to model predictions where the $\Delta$ is treated with its free mass.

10 pages, 3 Figures, to appear in the European Physical Journal A

References in corpus (6)

• Meson-nucleus potentials and the search for meson-nucleus bound states
• Spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron at low values of x and Q^2
• Determination of the Proton Spin Structure Functions for 0.05 < Q^2 < 5 GeV^2 using CLAS
• Measurements of polarized photo-pion production on longitudinally polarized HD and Implications for Convergence of the GDH Integral
• Measurement of the proton spin structure at long distances
• First Measurement of the Asymmetry and the Gerasimov-Drell-Hearn Integrand from $\overrightarrow{{}^{3}He}(\vec{\gamma },p)d$ reaction at the Incident Photon Energy of 29 MeV