🌐EnglishEnglishDeutschFrançaisPortuguêsTürkçeРусский한국어中文日本語EntityQ10380297· pop 7· linked from 5 articlesLandau–Yang theoremselection rule that a massive particle with spin 1 cannot decay into two photonsConnectionsChen-ning YangEntityquantum mechanicsEntityCategoriesLev LandauTheorems in quantum mechanics