Recent Progress in Ab-initio Four-Body Scattering Calculations.

In the first part of the contribution, we discuss the results of a recent benchmark calculation of n − H and p − He phase-shifts below the trinucleon disintegration thresholds. Three different methods-Alt, Grassberger and Sandhas, Hyperspherical Harmonics, and Faddeev-Yakubovsky-have been used and their results are compared. For both n − H and p − He we observe a rather good agreement between the three different theoretical methods. In the second part of the contribution, we study the longitudinal asymmetry $${A_z^{n^3{\rm He}}}$$ in the He( n, p)H reaction in order to obtain information about the parity-violating components of the nucleon-nucleon interaction. [ABSTRACT FROM AUTHOR]