  We study the Yangian of the sl(2|1) Lie superalgebra in a multi-parametric
four-dimensional representation. We use Drinfeld's second realization to
independently rederive the R-matrix, and to obtain the antiparticle
representation, the crossing and the unitarity condition. We consistently apply
the Yangian antipode and its inverse to the individual particles involved in
the scattering. We explicitly find a scalar factor solving the crossing and
unitarity conditions, and study the analytic structure of the resulting dressed
R-matrix. The formulas we obtain bear some similarities with those familiar
from the study of integrable structures in the AdS/CFT correspondence, although
they present obvious crucial differences.
