Flavour in particle physics Flavour quantum numbers Isospin: I or I3 Charm: C Strangeness: S Topness: T Bottomness: B′ Related quantum numbers Baryon number: B Lepton number: L Weak isospin: T or T3 Electric charge: Q X-charge: X Combinations Hypercharge: Y Y = (B + S + C + B′ + T) Y = 2 (Q − I3) Weak hypercharge: YW YW = 2 (Q − T3) X + 2YW = 5 (B − L) Flavour mixing CKM matrix PMNS matrix Flavour complementarity v t e