On 4 July 2012, physicists from all over the world celebrated the milestone achieved by CERN's Large Hadron Collider (LHC) in Geneva: they had found the elusive Higgs boson, described theoretically in 1964 and a key part of the standard model. Among the dozens of scientists who participated in that discovery, with the ATLAS and CMS experiments, there were many Spanish physicists, who ten years later appreciate what it meant.
Ilustración de un candidato a ser bosón de Higgs transformándose en dos fotones. CMS/CERN.
Director of the CPAN (Centro Nacional de Física de Partículas, Astropartículas y Nuclear), which includes all the Spanish groups involved in the discovery of the Higgs boson
The discovery in 2012 of the Higgs boson at CERN's Large Hadron Collider (LHC) in Geneva is as important for physics as the discovery of DNA in biology or the discovery of atomic and molecular structure in chemistry. From a technological point of view, it is a milestone comparable to the arrival of man on the moon, but its scientific repercussions are far greater.
A theoretical hypothesis, formulated in 1964 in order to understand the origin of the masses of the elementary constituents of matter, was confirmed 48 years later as a tangible ingredient of the real world: a new force field, imperceptible and enigmatic, which holds valuable secrets about some of the most burning questions in fundamental physics today: the replication in families of the elementary constituents of matter, the great disparity of their masses, the virtual absence of antimatter in the universe, the existence of dark matter, and so on.
The Higgs field raises many questions, but we still lack the right answers. In the coming days, the LHC will begin a new period of experimentation to scrutinise the new force field more precisely. A new and exciting stage of scientific research is beginning, and we hope that it will hold some big surprises.
The discovery of the Higgs boson in 2012 by CERN's ATLAS and CMS experiments was the cornerstone of the theoretical framework of particle physics that has reigned since the mid-20th century: the standard model. The equation written by Brout, Englert and Higgs in the 1960s that predicted the existence of this particle went from being a mere formula on a blackboard to a milestone in the history of science. And, although by that time man had already set foot on the moon, the fact that it took almost 50 years longer to discover it has only been the result of technological progress and the perseverance of physicists in their quest for knowledge of nature.
It is this perseverance that has led physicists to restart the LHC accelerator at a new energy level, which is now beginning on the 10th anniversary of its discovery, with the aim of unravelling new mysteries about the most fundamental components of the universe that the Higgs boson door has opened: dark matter and matter-antimatter asymmetry, among others. Not giving up is the key: other recent discoveries such as gravitational waves took almost a century from the time Einstein's theory of General Relativity predicted them to the confirmation of their existence.
But just the fact that science, and in particular major international collaborations such as CERN, has the power to unite nations and cultures makes the effort even more worthwhile in the times we live in, and perhaps serves as an example for peace between countries and continents.
The discovery in 2012 of the Higgs boson, the last ingredient of the standard model and responsible for the mass of elementary particles, is undoubtedly one of the most important discoveries in particle physics. It not only represents a theoretical and experimental milestone reached after 50 years of intense searching, requiring the design and construction of the LHC, the largest scientific and technological project of all time. The Higgs boson is a particle like no other in the standard model, the detailed study of which we hope will allow us to answer some of the most pressing questions about how nature works at its most fundamental level.
Over the last decade, the precision achieved at the LHC in the measurement of standard model processes, including the Higgs boson, as well as the ambition and creativity in the direct search for new physics, are enabling breakthroughs and perhaps the first cracks in the gleaming edifice of the standard model are already visible. With two decades of operation ahead of it, the LHC has not yet said its last word and revolutionary new discoveries may be awaiting.
However, despite its potential, the LHC has its limitations. In order to further penetrate the mysteries of the universe, new accelerators, capable of unprecedented precision and energy, are being designed.
I witnessed the atmosphere, the work and effort of the entire scientific community involved in the discovery, as well as the joy and excitement of achieving it. It should not be forgotten that there were relevant scientists who did not believe in its existence, Hawking among them. Since then, the properties of the Higgs have been experimentally verified and a deviation from the predictions of the standard model has been experimentally searched for.
So far, no sufficiently significant deviations have been found, although there are some data that show some tension between data and predictions. However, there is a need for more than the standard model, since the standard model has unknowns that need to be resolved. To this end, new accelerators of different types are being planned.