A surprising new duality discovered in theoretical particle physics

The scattering processes that can occur in proton collisions at CERN’s Large Hadron Collider show a new and surprising duality in theoretical particle physics.

A new and surprising duality has been discovered in theoretical particle physics. The duality exists between two types of scattering processes that can occur in proton collisions performed in the Large Hadron Collider (LHC) at CERN in Switzerland and France. Surprisingly, the fact that this link can be made indicates that there is something about the fine intricacies of the Standard Model of particle physics that is not fully understood. The Standard Model is a picture of the world at the subatomic scale that describes all the particles and their interactions. So when surprises happen, there is a need to grab attention. The scientific article has just been published in the journal Physical examination letters.

Mathias Guillaume

Matthias Wilhelm obtained his PhD at Humboldt University in Berlin before joining the Niels Bohr Institute in 2015. Since 2019, he has led a junior research group Villum Young Investigator, aiming to unravel the mathematical structures that govern our universe at the most small scales.

Duality in physics

The notion of duality appears in different fields of physics. The best-known duality is undoubtedly the particle-wave duality in quantum mechanics. The classic double-slit experiment shows how light acts like a wave, but Albert Einstein received his Nobel Prize for demonstrating how light behaves like a particle.

What is strange is that the light is actually both and neither the same time. There are simply two ways to look at this entity, light, and each comes with a mathematical description. Both with a completely different intuitive idea, but still describe the same thing.

“What we have now found is a similar duality,” says Matthias Wilhelm, assistant professor at the Niels Bohr International Academy. “We calculated the prediction for a diffusion process and for another diffusion process.

Our current calculations are less experimentally tangible than the famous double slit experiment, but there is a clear mathematical map between the two, and it shows that they both contain the same information. They are related, in a way.

Theory and experiments go hand in hand

At the Large Hadron Collider, we hit a lot of protons – within those protons are a lot of smaller particles, the subatomic gluons and quarks.

During the collision, two gluons of different protons can interact and new particles are created, such as the Higgs particle, resulting in complex patterns in the detectors.

Complex scattering process of particle physics duality

On the left side we have a diffusion process involving two gluons (green/yellow and blue/cyan) interacting to produce a gluon (red/magenta) and a Higgs particle (white). The more complex scattering process on the right is mirrored by the simpler one on the left, but here we have a scattering process of two gluons (green/yellow and blue/cyan) interacting to produce four gluons (red/magenta, red/yellow , blue/magenta and green/cyan). The black color symbolizes that in the collision itself many different elemental interactions can occur, and we have to add up all the possibilities. According to Heisenberg’s uncertainty principle, we cannot know exactly which possibility has occurred – so it is a “black box”. Credit: Søren J. Granat

We map the appearance of these patterns, and the theoretical work done in relation to the experiments aims to describe precisely what is happening in mathematical terms, in order to create an overall formulation, as well as to make predictions that can be compared to the results. of the experiences.

About CERN

CERN is the acronym for European Council for Nuclear Research, and the aim was to benefit from the sharing of expenses that this type of research entails, which would be too costly for a single country to bear.

There are currently 23 Member States. But equally important was international openness and the peaceful sharing of scientific advances in our knowledge of our world.

“We calculated the diffusion process for two gluons interacting to produce four gluons, as well as the diffusion process for two gluons interacting to produce a gluon and a Higgs particle, both in a slightly simplified version of the standard model.

To our surprise, we found that the results of these two calculations are related. A classic case of duality. Either way, the answer to the probability of one diffusion process occurring contains the answer to the probability of another diffusion process occurring.

The strange thing about this duality is that we don’t know why this relationship between the two different diffusion processes exists. We mix two very different physical properties of the two predictions, and we see the relationship, but it’s still a bit of a mystery where the connection lies,” says Matthias Wilhelm.

The principle of duality and its application

According to current understanding, the two should not be linked – but with the discovery of this startling duality, the only appropriate way to respond to it is to investigate further.

Surprises always mean that there is something we now know that we don’t understand. After the discovery of the Higgs particle in 2012, no new sensational particles have been discovered. The way we hope to detect new physics now is to make very precise predictions of what we expect, then compare them with very precise measurements of what nature is showing us, and see if we can find any deviations there. .

Niels Bohr and CERN

Niels Bohr was among the visionary researchers who, in the late 1940s, initiated the creation of an international research institution, which would allow researchers to collaborate to discover “what the universe is made of and how it works”, according to CERN’s mission. states.

The idea was and continues to be to push the boundaries of our knowledge of the world we live in.

We need a lot of accuracy, both experimentally and theoretically. But with more precision comes more difficult calculations. “So where that might lead is to see if this duality can be used to derive some kind of ‘mileage’ from it, because one calculation is simpler than the other – but it still gives the answer to the more complicated .calculation”, explains Matthias Wilhelm.

“So if we can get away with using simple math, we can use duality to answer the question that would otherwise require more complicated math – But then we really have to understand duality.

It is important to note, however, that we are not there yet. But usually, questions that arise from unexpected behavior of things are much more interesting than an orderly, expected outcome.

Reference: “Folding Amplitudes into Form Factors: An Antipodal Duality” by Lance J. Dixon, Ömer Gürdogan, Andrew J. McLeod and Matthias Wilhelm, March 15, 2022, Physical examination letters.
DOI: 10.1103/PhysRevLett.128.111602

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