Who was the Dutch theoretical physicist that created the 't Hooft η symbol?
Gerard 't Hooft Gerardus (Gerard) 't Hooft (] ; born July 5, 1946) is a Dutch theoretical physicist and professor at Utrecht University, the Netherlands. He shared the 1999 Nobel Prize in Physics with his thesis advisor Martinus J. G. Veltman "for elucidating the quantum structure of electroweak interactions".
3-j symbol In quantum mechanics, the Wigner 3-j symbols, also called 3"-jm" symbols, are an alternative to Clebsch–Gordan coefficients for the purpose of adding angular momenta. While the two approaches address exactly the same physical problem, the 3-"j" symbols do so more symmetrically, and thus have greater and simpler symmetry properties than the Clebsch-Gordan coefficients.