was regarded by his peers as a world-class elementary particle physicist at the time of his sudden death. He studied gauge theory and weak interactions. Research Gauge theory In 1964, Lee published an article about spontaneous symmetry breaking with his advisor Abraham Klein and contributed to the appearance of Higgs mechanism. He is often credited with the naming of the Higgs boson and Higgs mechanism. And in 1969, he succeeded individually the renormalization of the spontaneously breaking global gauge symmetry model. In the meantime, Dutch graduate student Gerardus 't Hooft was working in the case of local gauge symmetry breaking in the Yang–Mills theory using the Higgs mechanism. He met Lee and Symanzik at the Cargèse Summer School and consulted them on his work and got an insight. He finally succeeded in the renormalization of non-abelian gauge theory and won the Nobel Prize later for this work. David Politzer said in his 2004 Nobel Lecture that the particle physicists community at that time learned all from Lee who actually combined insights from his own work and from Russian physicists' work and encouraged 't Hooft's paper. Charm quark Glashow, Maiani and Iliopoulos predicted charm quarks to match the experimental results. Lee wrote an article with Gaillard and Rosner and predicted the mass of the charm quarks by calculating the quantities which correspond to the mixing and decay of K meson. Cosmology In 1977, Lee and Weinberg wrote an article about the lower bound on heavy neutrino mass. In this paper, they revealed that if the heavy and stable particles in the early universe which can only be transferred into other particles through the pair annihilation remain as relics after the universe's expansion, then the strength of the interaction should be bigger than 2 GeV. This calculation can be applied to find the amount of the dark matter. This bound is called the Lee-Weinberg bound. Lee's promotion of gauge theories Weinberg's 1967 paper A Model of Leptons has over 15,000 citations and played a key role in the award of his 1979 Nobel prize. In 1972 at a conference at Fermilab, Lee gave a talk Perspectives on Theory of Weak Interactions that brought Weinberg's 1967 paper out of obscurity and explained many aspects of gauge theories to a large audience. Controversy over death A South Korean fictional novel allegedly based on Lee's death was published in 1993, which presumably suggested that Lee