When the Higgs boson was first experimentally measured in 2012 by CERN’s Large Hadron Collider after more than 30 years of hard work, many in the scientific community expected the discovery to usher in a new era in particle physics. But a recent study suggests that physicists will have to be patient before that happens.
This great adventure began in 1964 with Peter Higgs, the researcher who gave his name to this object. At the time, he was seeking to unravel the mysteries of theinteraction forteone of the four fundamental forces of nature—the one that holds the nuclei of atoms together. According to the models of the time, the particles that embody this force, the bosons, should be completely massless. However, this idea was apparently inconsistent with the laws of quantum physics, formalized in what is now called the standard model of particle physics (the theoretical framework that describes the behavior of matter at the smallest of scales).
To reconcile the concept with theory, Higgs proposed that the Universe was traversed by an invisible energy field, capable of imposing a kind of resistance to the particles passing through it – a bit like a viscous liquid that would slow down the progress of a swimmer. It is this interaction that would give their mass to all the particles in the universe.. In the process, he suggested that fractions of this field could materialize in the form of a new object that allows other particles to interact with this field to obtain this mass: the now famous boson de Higgs.
The idea, particularly exotic at the time, was initially rejected. But things began to change in 1967 with Steven Weinberg’s work on the electroweak interaction, which allowed particle physics to be understood from a completely new angle. In this new framework, the Higgs boson found new life, and many researchers set out to find this object that could revolutionize fundamental physics. It took several more decades for CERN to finally measure it using the world’s most powerful particle accelerator.
The potential key to a ” new physics »
This discovery came as a bolt from the blue, and for good reason: the Higgs boson was the last object predicted by the standard model whose existence had not yet been experimentally confirmed. Many academics were therefore convinced that it was a central piece of the great puzzle of the universeand that his discovery would profoundly transform our understanding of the world around usIt is because of this special status that the Higgs boson is sometimes nicknamed ” God particle “, even if this term is generally not very appreciated by specialists.
Without further ado, physicists have embarked on a long-term quest to better understand the role of this particle. For twelve years now, they have been trying to describe its properties as precisely as possible, hoping to get their hands on a revolutionary phenomenon that could effectively shake up the entire discipline. But it is clear that the results have been rather mixed at this level. Until now, the analysis of the boson has not revealed the slightest element likely to open the door to a ” new physics ».
But researchers are not giving up hope; it is quite possible that the long-awaited key still lies in the Higgs boson. The challenge is to find a phenomenon incompatible with the standard model, a flaw into which researchers can infiltrate to break the status quo.
A difficult particle to tame
The problem is that this is much easier said than done. This particle is notoriously difficult to analyze, for both experimental and computational reasons. To produce this famous boson for study, LHC operators send particles crashing into each other at prodigious speeds within a gigantic tube several kilometers long. These impacts then produce a cascade of sub-particles whose distribution and trajectory are analyzed using extremely sophisticated mathematical tools — and this is where researchers are faced with a serious problem.
Indeed, the complexity of these analyses is such that physicists generally allow themselves some shortcuts in processing some parameters. There are some whose influence is considered negligible, such as the influence of certain particles with infinitesimal mass. Physicists therefore choose to ignore them and compensate with predefined values that greatly simplify the calculations.
This approach has allowed us to avoid total stagnation, but it is not without consequences. Everyone is well aware that these approximations could cause us to miss phenomena that are certainly subtle and discrete, but nevertheless essential for understanding the properties of the boson in its entirety, with all that this implies for the standard model.
An uncompromising analysis
The authors of this new study decided that it was high time to conduct a comprehensive study, limiting these shortcuts to the bare minimum, to find signs of this ” new physics ». « The essence of our work was our desire to take into account some corrections that are generally neglected because of their apparently very small contribution. “, summarizes Michal Czakon, co-author of the paper.
At the end of this long-term work, Czakon and his colleagues found that some parameters that are usually overlooked could actually have a significant influence on the final result of the analysis. But the soufflé was soon to fall, because the team also arrived at a much less exciting conclusion: in the end, The results of their analysis remained extremely close to those obtained by the other teams by ignoring all these outrageously complex corrections.
« The values found by our group and measured during previous beam collisions at the LHC are practically the same, naturally taking into account current calculation and measurement inaccuracies. ” explains co-author René Poncelet.
The standard model holds up
In other words, even when analyzing the behavior of the boson with unprecedented rigor, we still do not see any unexpected phenomenon emerging. None of these analyses point to a flaw in the standard model.which would be essential to open the way to a great upheaval in modern physics. There seems to be no sign of new physics in the mechanisms responsible for the formation of the Higgs bosons we are studying, at least for now. “, says Poncelet.
Back to square one, then? Not necessarily. This is far from the first time that the Standard Model has proven unshakeable in the face of physicists’ attacks. It is no coincidence that it serves as the basis for much of modern physics; it describes the phenomena we observe in our world extremely well.
But this is also true of Einstein’s relativity—and it just so happens that the two models are completely irreconcilable at some levels. Gravity, for example, is a major sticking point. It is very well described by general relativity, but there is nothing in the standard model that would explain it. And this is just one isolated example among many. So there must be something wrong with our current description of the universe.
This is precisely why physicists are constantly testing the limits of these models through entities such as the Higgs boson. Since the latter is still relatively poorly understood, researchers are still far from having exhausted all potential avenues. In summary, it remains a promising subject of study; even if there is no guarantee that a ” new physics ” does indeed exist or that the Higgs boson is its embodiment, it is still far too early to throw in the towel.
It will therefore be important to follow CERN’s work with the LHC closely. The accelerator is currently in the middle of its fourth scientific campaign, and valuable data will therefore continue to fall over the coming years. With a bit of luck, they will highlight the flaws in the standard model that physicists have been tracking for decades.
The text of the study is available ici.
Source: www.journaldugeek.com
