Prof Lochlainn O Raifeartaigh, a physicist who had a theorem named after him, has died in Dublin aged 67 following a brief illness.
Prof O Raifeartaigh was best known for his research on the symmetries of physical theories.
He spent most of his career as a senior professor at the Dublin Institute for Advanced Studies. In August his research work was recognised when he won the Wigner Medal.
His reputation was first established in the 1960s at Syracuse University when he became well known among physicists for the theorem which showed that the symmetries of the universe that arise from the theory of relativity place restrictions on the mass spectra of elementary particles.