We analyze the free energy of the integrable two dimensional O(4) sigma model in a magnetic field. We use Volins method to extract high number (2000) of perturbative coefficients with very high precision. The factorial growth of these coefficients ar
e regulated by switching to the Borel transform, where we perform several asymptotic analysis. High precision data allowed to identify Stokes constants and alien derivatives with exact expressions. These reveal a nice resurgence structure which enables to formulate the first few terms of the ambiguity free trans-series. We check these results against the direct numerical solution of the exact integral equation and find complete agreement.
