A low-energy calculation of ${}^9\mathrm{Be}$ photodisintegration cross section is presented within an $\alpha \alpha n$ cluster approach. The $\alpha n$ and $\alpha \alpha$ contact interactions are derived from cluster effective field theory. The two-body potentials defined in momentum space are regularized by a Gaussian cutoff. The associated low-energy constants are found by comparing the calculated low-energy $T$ matrix with its effective range expansion. A three-body state-dependent potential is also introduced in the model. First, the ${}^9\mathrm{Be}$ three-body binding energy is studied within the nonsymmetrized hyperspherical harmonics method. Then, the low-energy cross section is calculated via the Lorentz integral transform method, focusing on the dominant electric dipole transitions. A twofold evaluation of the nuclear current matrix element is presented, employing both the electric dipole transition operator (Siegert theorem) and the one-body convection current operator. This approach is adopted to allow for a discussion of the effect of the many-body currents.

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• Effective field theory
• Few-body systems
• Photonuclear reactions
• 6 ≤ A ≤ 19
• Ab initio calculations
• Cluster models
• Hyperspherical method