文摘
We report a study on the low-energy properties of the elastic s-wave scattering of a neutron (n) in the carbon isotope \(^{19}\)C near the critical condition for the occurrence of an excited Efimov state in the three-body n–n–n class="InlineEquation" id="IEq5">\(^{18}\)C system. For the separation energy of the two halo neutrons in \(^{20}\)C we use the available experimental data. We also investigate to which extent the universal scaling laws, strictly valid in the zero-range limit, will survive when using finite-range interactions. By allowing to vary the n–n class="InlineEquation" id="IEq7">\(^{18}\)C binding energy, a scaling behavior for the real and imaginary parts of the s-wave phase-shift \(\delta _0\) is verified, emerging some universal characteristics given by the pole-position of \(k\cot (\delta _0^R)\) and effective-range parameters.