Mary K. Gaillard, a theoretical physicist known for her contributions to the Standard Model of physics, passed away on May 23 at her home in Berkeley. She was 86. Gaillard's work in the field of elementary particles helped validate theories about quarks and other fundamental components of matter.

Gaillard had an early interest in physics and pursued it despite gender barriers in the 1960s and '70s. She faced challenges as a woman in science but persisted, earning her doctorate from Paris-Saclay University while raising three children. Her work included collaborations with notable physicists like Murray Gell-Mann and John Ellis.

At CERN, she was a visiting scientist from 1964 until she joined UC Berkeley in 1981 as its first tenured female professor of physics. Her research focused on particle properties, decay modes, and interactions within the framework of quantum chromodynamics (QCD).

“She was one of the early believers in the quark theory before most people had cottoned on,” said Lawrence Hall, a UC Berkeley professor.

Gaillard also advocated for women in science through reports on inequality at CERN and mentorship roles throughout her career. She co-directed international programs like the Les Houches Summer School and served on various committees promoting women's status in physics.

Her achievements were recognized with awards such as the E.O. Lawrence Award and J.J. Sakurai Prize for Theoretical Particle Physics. Gaillard's legacy includes significant scientific contributions and support for future generations of physicists.

She is survived by three children, seven grandchildren, and her former husband Jean-Marc Gaillard.