Peter Higgs passed away at age 94, his legacy will continue driving physics for decades to come

Peter Higgs (29 May 1929 – 8 April 2024) made significant theoretical contributions in elucidating the fundamental mechanism by which elementary particles acquire mass. His work laid the foundation for decades of research and led to the discovery of a new boson, named after him: the Higgs boson, in 2012.

The mechanism, which relies on a new field and spontaneous symmetry-breaking, was proposed in 1964 by Peter Higgs at the University of Edinburgh. Independently, similar conclusions were reached by Robert Brout and François Englert at the Université Libre de Bruxelles, and by Gerald Guralnik, C. R. Hagen, and Tom Kibble at Imperial College London, around the same time.

Higgs reportedly developed the fundamentals of his theory after returning to his Edinburgh New Town apartment from a failed weekend camping trip to the Highlands. He stated that there was no "eureka moment" in the development of the theory. He wrote a short paper exploiting a loophole in Goldstone's theorem (massless Goldstone particles need not occur when local symmetry is spontaneously broken in a relativistic quantum field theory) which he published in 1964. Higgs wrote a second paper describing a theoretical model (now called the Brout-Englert-Higgs mechanism), but the paper was rejected (the editors of Physics Letters judged it "of no obvious relevance to physics"). Higgs wrote an extra paragraph, explicitly mentioning that this mechanism entails a new massive spin-zero boson (later named the Higgs boson) and resubmitted it to Physical Review Letters, where it got accepted for publication. The same mechanism in a non-relativistic setting had already been proposed earlier in 1962 by Philip Anderson.

At the time of his retirement in 1996, Higgs doubted that a similar breakthrough could be achieved in today's academic culture. He cited the pressure on academics to collaborate and constantly produce papers, saying, "It's difficult to imagine how I would ever have enough peace and quiet in the present sort of climate to do what I did in 1964."

It would take nearly half a century for their theory to be experimentally confirmed. On July 4, 2012, during a special seminar at CERN, the ATLAS and CMS experiments announced that they had observed strong indications for the presence of a new particle, which could be the Higgs boson, in the mass region around 126 GeV. Higgs, who was a special guest at this seminal seminar along with Englert, commented, "It's really an incredible thing that it's happened in my lifetime."

In recognition of their contributions, Peter Higgs and François Englert were jointly awarded the Nobel Prize in Physics in 2013. Their theoretical work and the discovery of the Higgs boson stand out as an example of the deep consequences of mathematical symmetries in the physical world.

Ever since the discovery of this new boson by the ATLAS and CMS experiments in 2012, data taking at the Large Hadron Collider continues and statistical samples containing Higgs candidate events are collected. Measuring all properties (mass, spin, width, couplings to other bosons and fermions) to establish empirically whether this new particle fullfils all what is required to be the Standard Model Higgs boson, or whether there is room for more. This new boson could still be the lightest of a Higgs multiplet in models where five Higgs bosons are predicted, as e.g. Super Symmtry would demand, also a possible substructure of this new boson, where the Standard Model Higgs boson is predicted structure less, would establish new routes for particle physics to go. Furthermore, the Higgs boson might interact with yet-to-be-discovered particles. Among these, dark matter particles emerge as prime candidates for investigation. Understanding the potential coupling between the Higgs boson and such elusive particles could offer profound insights into the nature of dark matter and its role in the universe.

Peter Higgs leaves behind a monumental legacy, defined not only by his scientific achievements but also by his inspiring personality. The impact of Higgs physics and the exploration of the intricacies of the Brout-Englert-Higgs mechanism will endure throughout the coming decades with high priority. Indeed, the European Particle Physics Strategy Update from 2020 identifies an electron-positron Higgs factory as the highest-priority next collider to be envisioned, where precision measurements and new insights become possible that are unachievable today.

Hans Peter Beck

_{[Released: July 2024]}