Professor Zackaria Chacko has been elected Fellows of the American Physical Society. APS Fellowship recognizes excellence in physics and exceptional service to the physics community.
Chacko, who is a member of the Maryland Center for Fundamental Physics (MCFP), was cited for discovering two of the major theoretical scenarios for particle physics beyond the Standard Model — neutral naturalness and gaugino mediated supersymmetry breaking — and for inspiring experimental programs to test them.
Following his B.S. and M.S. degrees at the Indian Institute of Technology, Kharagpur, Chacko earned his Ph.D. in Physics at the University of Maryland in 1999, working with Markus Luty. While a graduate student at Maryland, he received the Michael J. Pelczar Award for Excellence in Graduate Study and was named an Outstanding Teaching Assistant.
He then held postdoctoral positions at the University of Washington and the University of California, Berkeley, before accepting the role of Assistant Professor at the University of Arizona. In 2007, he returned to the University of Maryland. He was promoted to Associate Professor in 2009 and full Professor in 2016. He has served on the department’s Priorities, Curriculum Review, and Graduate Admissions committees, and is currently a member of the editorial board of JHEP, the premier journal dedicated to elementary particle physics.
The primary focus of Chacko’s research is on proposing new theories that address the known problems of the Standard Model of particle physics which can be tested in current and future experiments. The work for which he received the award is related to a theoretical problem of the Standard Model, known as the “hierarchy problem”. The Higgs boson has a mass of order the weak scale, the mass scale of the force carriers of the weak interactions. However, in the Standard Model, quantum effects tend to make the Higgs many orders of magnitude heavier than the observed value. The fact that the Higgs is light then arises from a very delicate cancellation between completely independent effects, which seems extremely contrived.
An elegant class of solutions to the hierarchy problem involve extending the Standard Model to include new particles related to the known particles by a new symmetry of nature. The quantum effects of the new particles cancel against those of the Standard Model, explaining the lightness of the Higgs boson. Chacko was recognized for proposing two paradigms that realize this framework, gaugino mediated supersymmetry breaking and neutral naturalness, which have been enormously influential in the field and inspired novel experimental searches to discover them.
“Chacko’s APS Fellowship highlights his highly original and influential proposals to solve one of the deepest mysteries of particle physics, the Hierarchy Problem,” said Raman Sundrum, Director of the MCFP. “This distinction is richly deserved.”