Two-peak soliton in the CKP hierarchy

We present a systematic approach to the construction of soliton solutions for the 5-reduction of the C-type sub-hierarchy for the Kadomtsev-Petviashvili (CKP) hierarchies starting from the general τ-function τ(n+k) of the Kadomtsev-Petviashvili (KP) hierarchy. We obtain the one-soliton and two-soliton solutions for the bi-directional Kaup-Kupershmidt (bKK) equation, i.e. the 5-reduction of CKP hierarchy.