From Japanese-English FreeDict Dictionary ver. 0.1: Σ /(el)sˈiɣma(ja)/, σ /(el)sˈiɣma(ja)/, ς /(el)sˈiɣma(ja)/, シグマ /ɕiɡˈɯᵝmä/ (noun (common) (futsuumeishi)) sigma
Σ /(el)sˈiɣma(ja)/, σ /(el)sˈiɣma(ja)/, ς /(el)sˈiɣma(ja)/, シグマ /ɕiɡˈɯᵝmä/ (noun (common) (futsuumeishi)) sigma