Computations of Scattering Lengths in nnpp System within Cluster Reduction Method for Yakubovsky Equations

The elastic and rearrangement processes in the four nucleon system with two clusters in the initial and final states can be treated adequately in framework of Yakubovsky differential equations (YDE) approach. Unfortunately, a direct application of YDE to the scattering problem requires huge computer resources. It is why, new methods allowing a reduction of comlexity of YDE are of interests from the point of view of practical calculations. In papers [1], the authors proposed a method which reduces the YDE to the equations for the functions describing the relative motions of clusters. This method of cluster reduction (CRM) was successfully applied to calculations of n–H scattering in [1]. It is worth to note that the exact four nucleon calculations of n–H scattering were performed on a personal computer what can characterize an efficiency of CRM. In this report we give a sketch of CRM and our recent results of calculations of scattering lengths in the four nucleon system.