Low- and intermediate-energy nucleon-nucleon interactions and the analysis of deuteron photodisintegration within the dispersion relation technique

A.V. Anisovich; V.A. Sadovnikova

EPJ

A.V. Anisovich - V.A. Sadovnikova

Petersburg Nuclear Physics Institute, Gatchina, St.Petersburg 188350, Russia

Received: 24 November 1997 Communicated by B. Povh

Abstract
Nucleon-nucleon interactions in the region of the nucleon kinetic energies up to 1000 MeV are analysed together with the reaction $\gamma d \to pn$ in the photon energy range up to $E_{\gamma}=400$ MeV. The following nucleon-nucleon s-channel partial amplitudes are reconstructed in the dispersion relation N/D method: ¹S₀, ³S₁-³D₁, ³P₀, ¹P₁, ³P₁, ³P₂, ¹D₂, ³D₂ and ³F₃. Correspondingly, the dispersive representation of partial amplitudes $N\Delta \to pn$ , $NN^* \to pn$ and $NN\pi \to pn$ is given and parameters which determine these two baryon amplitudes are found. Basing on that, we have performed parameter-free calculation of the amplitude $\gamma d \to pn$ , taking into account: (i) pole diagram, (ii) nucleon-nucleon final-state rescattering $\gamma d \to pn \to pn$ , and (iii) inelastic final-state rescatterings $\gamma d \to N\Delta(1232)$ $\to pn$ , $\gamma d \to NN^*(1400) \to pn$ and $\gamma d \to NN\pi \to pn$ . The $\gamma d \to pn$ partial amplitudes for the above-mentioned channels are found. It is shown that the process $\gamma d \to pn \to pn$ is significant for the waves ¹S₀, ³P₀, ³P₁, at $E_{\gamma} =50 -100$ MeV, while $\gamma d \to N\Delta \to pn$ dominates for the waves ³P₂, ¹D₂, ³F₃ at $E_{\gamma} \gt 300$ MeV. Meson exchange current contributions into the deuteron disintegration are estimated: they are significant at $E_\gamma =100-400$ MeV.