CERN Accelerating science

The rise of the axions!

by Panagiotis Charitos

Roberto Peccei and Helen Quinn worked together in developing what is today known as the Peccei-Quinn symmetry; a mechanism that addresses the strong CP-violation that consequently led to the invention of axions and inspired an intense experimental and theoretical programme for more than three decades.

In this special issue dedicated to axion-searches at CERN we interview Roberto Peccei and Helen Quinn about the ideas that led to the formulation of this mechanism and the present and future challenges in particle physics. The possible existence of axions in the universe means that they are a candidate for (very) cold dark matter.

Helen Quinn, a professor emerita at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University, received the 2018 Benjamin Franklin Medal in Physics last April for her accomplishments in the field of particle physics.  

“I was lucky to be there at the time when the Stanford Linear Accelerator Center was being built.” SLAC was the world’s longest linear accelerator and promised unprecedented explorations of the subatomic world. “Really, the beginning of my interest was the fact that particle physics was bubbling at that time at Stanford, and that’s where I got hooked on it.” Quinn thinks that an important element in any scientist’s career is the opportunity to meet inspiring colleagues and interact with teams working at the forefront of research. Enthusiasm for a problem seems to be contagious

Read the full interview HERE


Roberto Peccei, is a world renowned theoretical physicist working in the interface between astroparticle physics and cosmology. He is probably best known for his work on strong CP violation. Together with Helen Quinn, Peccei suggested a mechanism to address the strong CP problem, a major blemish of the Standard Model of particle physics- namely its failure to explain why the fundamental laws of physics in the strong interactions look the same if you run time backwards.

Following his PhD, Peccei became a post-doctoral fellow at the University of Washington in Seattle and after that was offered a position as Assistant Professor at Stanford. “This is where I first met Helen Quinn, who was a visiting Professor from Harvard University. We both had similar interests related to the existence of instantons in the strong interactions and soon we started working together. One of the first things that we tried to understand was how instantons lead to fermion number violation."

To read the full interview click HERE 


A Q&A with Pierre Sikivie, another axion pioneer, discussing the technique that he invented in 1983 for detecting axions and the experimental challenges lying ahead. 

I am happy to recount how the axion haloscope (to detect dark matter axions) and the axion helioscope (to detect solar axions) were invented.

Back in the early 80s, it was thought that the Strong CP Problem may be solved by an axion which is very light and very weakly interacting, the so-called "invisible axion". I became a junior faculty member at the University of Florida around that time.  My first teaching assignment was graduate level electromagnetism and as you may guess, I did many problems in J.D. Jackson's famous book on the subject.

To read the full interview click HERE