  We study two-body non-Hermitian physics in the context of an open dissipative
system depicted by the Lindblad master equation. Adopting a minimal lattice
model of a handful of interacting fermions with single-particle dissipation, we
show that the non-Hermitian effective Hamiltonian of the master equation gives
rise to two-body scattering states with state- and interaction-dependent
parity-time transition. The resulting two-body exceptional points can be
extracted from the trace-preserving density-matrix dynamics of the same
dissipative system with three atoms. Our results not only demonstrate the
interplay of PT symmetry and interaction on the exact few-body level, but also
serve as a minimal illustration on how key features of non-Hermitian few-body
physics can be probed in an open dissipative many-body system.
