  We study the phenomenology associated with a light bino-like neutralino with
mass under the tau mass in the context of the R-parity violating Minimal
Supersymmetric Standard Model. This is a well-motivated example of scenarios
producing potentially light and long-lived exotic particles, which might be
testable in far-detector experiments, such as the FASER experiment at the Large
Hadron Collider. A quantitative assessment of the discovery potential or the
extraction of limits run through a detailed understanding of the interactions
of the light exotic fermion with Standard Model matter, in particular, the
hadronic sector. Here, we propose a systematic analysis of the decays of such a
particle and proceed to a model-independent derivation of the low-energy
effects, so that this formalism may be transposed to other UV-completions or
even stand as an independent effective field theory. We then stress the
diversity of the possible phenomenology and more specifically discuss the
features associated with the R-parity violating supersymmetric framework, for
example neutron-antineutron oscillations.
