I need to understand the basic difference between the two integrable models given below.
same signs of dispersion and interaction strengths in Manakov model
1q_{i}t + q_{i}xx+2(|q_{i}|^2 +|q_{j}|)q_{i}=0 where i,j=1,2
Opposite signs of dispersion and interaction strengths in Manakov model
1q_{i}t - q_{i}xx+2(|q_{i}|^2 +|q_{j}|)q_{i}=0 where i,j=1,2
Kindly do clarify....