Long time asymptotics behavior of the focusing nonlinear Kundu-Eckhaus equation

Abstract: We study the Cauchy problem for the focusing nonlinear Kundu-Eckhaus equation and construct long time asymptotic expansion of its solution in fixed space-time cone with $C(x_1,x_2,v_1,v_2)={(x,t)\in\Re^2:x=x_0+vt$ $x_0\in[x_1,x_2],v\in[v_1,v_2] }$. By using the inverse scattering transform, Riemann-Hilbert approach and $\overline\partial$ steepest descent method we obtain the lone time asymptotic behavior of the solution, at the same time we obtain the solitons in the cone compare with the all N-soliton the residual error up to order $\mathcal{O}(t^{-3/4})$.