Question: What is the type of particle of the concept that was proposed by the Soviet physicist who also discovered the theory of superfluidity?
Sentence (from "Lev Landau"): Lev Davidovich Landau (Russian: Лев Дави́дович Ланда́у ; ] ; January 22 [O.S. January 9] 1908 1 April 1968) was a Soviet physicist who made fundamental contributions to many areas of theoretical physics.
Relevant evidence: No