Demir works at Izmir Institute of Technology, Izmir, Turkey. After obtaining his PhD in 1995 at the Middle East Technical University, Turkey, he has worked as a research associate at the University of Pennsylvania (1996-97), ICTP (1998-2000) and TPI, Minnesota (2000–03). He has given notable contributions to physics of Higgs bosons and phenomenology of the supersymmetric models of nature. In recent years, his research has been focusing on "naturalness problem" in the Higgs boson mass and in the vacuum energy. He has been working and reporting on gravity-assisted naturalness programme. He was Turkey’s national representative in CERN’s Strategy Council Meeting in 2006. He has received awards by a number of national institutions. He is the first Turkish-citizen researcher to win the Alexander von Humboldt Foundation Friedrich Wilhelm Bessel Research Award (2006).