/** *

• Focused Angular N-body event Generator (FANG)
• \authors: Arik Kreisel and Itay Horin
• FANG is a Monte Carlo tool for efficient event generation in restricted
• (or full) Lorentz-Invariant Phase Space (LIPS). Unlike conventional approaches
• that always sample the full 4pi solid angle, FANG can also directly generates
• events in which selected final-state particles are constrained to fixed
• directions or finite angular regions in the laboratory frame.
• Reference: "Focused Angular N-Body Event Generator (FANG)" paper
• https://arxiv.org/abs/2509.11105 Published in JHEP */