Professor Arttu Rajantie's research focuses on applications of quantum field theory in cosmology and particle physics. He is on sabbatical for the 2025-26 academic year, spending time at CERN as a Scientific Associate in the Theoretical Physics department and at the University of Oxford, where he is a Visiting Fellow of Wadham College and an academic visitor in the Department of Physics. He is also a member of the MoEDAL experiment, searching for magnetic monopoles produced in proton-proton and heavy-ion collisions at the Large Hadron Collider.

Rajantie did his PhD at the University of Helsinki, Finland, and joined Imperial College in 2005 after postdoctoral positions at the Universities of Sussex and Cambridge.