noun
one particle irreducible
Technical term in quantum field theory; refers to Feynman diagrams that cannot be disconnected by cutting a single internal line.
一粒子既約なダイアグラムは、くりこみ群の解析で重要である。
One-particle-irreducible diagrams are important in renormalization group analysis.
Compound of 一 (one), 粒子 (particle), 既約 (irreducible). A direct translation of the English physics term 'one particle irreducible'.