Archimedes of Syracuse was possibly the first scientist known to have described nature from axioms. Scientists since then, from Newton to Laplace to Einstein, have endeavored towards a unifying “theory of everything” to explain all physical aspects of the universe.

In the Standard Model of particle physics, the Higgs boson is a particle that explains why some fundamental particles have mass when they should be massless. It is extremely difficult to detect because of the sheer amount of energy required to produce them and since they break apart in about ten-sextillionth (10^-22) of a second. Unfortunately, the ephemeral nature of the Higgs boson has not only led to the creation of its mainstream sobriquet – the God’s particle – but has made in-depth research into its transient and complex physics inaccessible to most.

Research conducted by Professor Bumjoon Kim from the Department of Physics at Pohang University of Science and Technology in collaboration with the research team from the Max Planck Institute for Solid State Research has made great contributions to understanding the physical universe by creating a platform for research into the condensed-matter analogue of the Higgs boson known as the Higgs mode. Through this novel method, the team has made its mark on history by becoming the first in the world to observe the decay process of the Higgs mode. This achievement has been published in the world-renowned Nature Physics.

Observation of the decay process have previously been out of reach for scientists owing to its rapid decay. As a solution, the research team studied the two-dimensional antiferromagnet Ca₂RuO₄ using spin-polarized inelastic neutron scattering. By analyzing the abstract shape of the spin waves, they discovered a well-defined and dispersive Higgs mode which rapidly decays into modes reminiscent of another Standard Model particle called Goldstone bosons. In other words, the team has found an accessible condensed-matter analogue approach that could result in the proliferation of research into the dynamics of the Higgs.

Professor Kim remarked on the noteworthiness of this observation because it was achieved in a small laboratory setting without the need of massive infrastructure. Further research will be conducted to verify whether the decay process fully describes its dynamics, but nonetheless, this study represents the first step towards parallel development in condensed-matter physics

This study received financial support from the German Science Foundation via the coordinated research program SFB-TRR80, and from the European Research Council via Advanced Grant 669550.