Precise comparison of the Gaussian expansion method and the Gamow shell model

We perform a detailed comparison of results of the Gamow shell model and the Gaussian expansion method supplemented by the complex scaling method for the same translationally invariant cluster-orbital shell model Hamiltonian. As a benchmark test, we calculate the ground state 0⁺ and the first excited state 2⁺ of mirror nuclei ⁶He and ⁶Be in the model space consisting of two valence nucleons in a p shell outside of a ⁴He core. We find a good overall agreement of results obtained in these two different approaches, also for many-body resonances. (authors)