In the kingdom of fundamental physics, two factions are engaged in a merciless struggle since the dawn of time: “ordinary” material and its alter ego, antimatière. The two are populated by particles almost identical to their twins, with a few exceptions – their electrical loads and a handful of other quantum properties, which are opposite.
This symmetry has very concrete consequences. Indeed, when matter and antimatter meet, they are annihilated each other by releasing a large amount of energy in the form of gamma rays, a bit like eternal rivals which would clash in the last battle of a work of fiction.
This phenomenon has largely contributed to the notoriety of antimatter in popular culture, especially in science fiction where it often plays a preponderant role. But it also has deep implications in fundamental science, especially in cosmology, where annihilation is one of the cornerstone of models describing the evolution of the universe from the Big Bang.
The study of the antimatter is therefore of crucial importance. But even if physicists have made enormous progress since the idea was proposed by the illustrious Paul Dirac, we are still very far from having pierced all its secrets. It is in particular at the heart of one of the most tenacious enigma of all modern science: Material-antimatter asymmetry.
One of the great mysteries of physics
Initially, physicists believed that matter and antimatter had been created in quantities perfectly equal to the dawn of the universe. However, this scenario is completely incompatible with observable reality; If that was the case, almost all the existing atoms would have been annihilated immediately after the Big Bang, including those that constitute the world in which we live today!
An inconsistency that prompted theorists to reconsider this scenario: they now believe that an imbalance has enabled the material to emerge in greater quantity than the antimatter. This interpretation has the merit of explaining why the whole universe is not exclusively populated by photons – but it also brings about another question oh so thorny: Where could this asymmetry come from?
Unfortunately, the answer is anything but obvious. After a century of concerted efforts of the greatest geniuses of fundamental physics, no one has succeeded in determining the origin of this mysterious asymmetry … for the moment, because the last works of the CERN could change the situation.
Loading symmetry, the needle in the hay boot
To unravel the sons of this mystery, CERN physicists sought a difference in the behavior of particles of matter and antimatter, with the hope that it reveals clues to the origin of asymmetry.
More specifically, they focused on the load-treatment symmetry, or CP symmetry. It is A fundamental property which, if it were infringement, could explain how the material ended up prevailing on the antimatter in the primordial universe.
This approach had already borne fruit in the 1960s, when researchers observed a violation of CP symmetry in shades – unstable particles involved in the interaction between protons and neutrons – and their antimatter equivalents.
Finally asymmetry in ordinary matter
Following this discovery, the physicists therefore hastened to seek a similar violation in another family of particles: the baryonswhich constitute almost all the matter around us
And even if it took more than 65 years, this work has finally borne fruit; CERN physicists have finally found a violation of CP symmetry in bars λb (« lambda-b »).
It turns out that the latter disintegrate 5 % more often than anti-baries into a set of very specific subatomic particles. This difference may seem anecdotal, but, statistically speaking, it is significant enough to affirm that ordinary matter does not behave exactly like antimatter. And this could have considerable repercussions on our understanding of the universe.
« We have now observed differences in behavior between matter and antimatter within the particle group which dominates the known matter of the universe. This could make it possible to better understand why this situation happened after the Big Bang “Explains William Barter, member of the CERN LHCB collaboration, in a post on The Conversation.
Now that this difference has been clearly highlighted, CERN troops will be able to analyze it more precisely in order to determine the implications. With a little luck, this will allow you to discover a new fundamental particle, or a new physical mechanism likely to explain the great asymmetry to which we owe our existence.
The study text is available here.
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