Three roads to the energy gap

Understand

We determine analytically the energy gap at weak coupling in the attractive multi-component Gaudin--Yang model, an integrable model which describes interacting fermions in one dimension with $\kappa$ components.

• We use three different methods.
• The first one is based on a direct analysis of the Bethe ansatz equations.
• The second method uses the theory of resurgence and the large order behavior of the perturbative series for the ground state energy.