Gaja Alaga (3 July 1924 – 7 September 1988) was a Croatian theoretical physicist who specialised in nuclear physics.
He was born in noble family of Bunjevac origin in the village of Lemeš (today called Svetozar Miletić) in northwestern Bačka in Kingdom of SHS (today in autonomous province Vojvodina, Serbia).
This discovery was key to the development of new nuclei models which confirmed that subatomic particles can distort the shape of the nucleus.
This is by the model for collective motion (based on nuclei deformed from a spherical shape, but with axial symmetry) for which Aage Bohr, Ben Roy Mottelson, and James Rainwater won the 1975 Nobel Prize.
The so-called Alaga rules are in common use among specialists in nuclear structure, in comparing theoretical transition rates with measurements.