The merging of jets
In perturbative QCD matrix elements, the invariant mass of parton pairs is normally peaked at low values, due to the singularities of the q → qg and g →gg subprocesses. Whereas pairs at large invariant masses give rise to separately visible jets, one may expect a continuous merging back into one single jet, q or g, when the qg or gg invariant mass becomes small. Within the framework of string frag
