Apr 26 2022Reviewed by Alex Smith

**In theoretical particle physics, a new and interesting duality has been discovered. The duality exists between two kinds of scattering processes that are likely to take place in the proton collisions made in the Large Hadron Collider at CERN in Switzerland and France.**

The fact that this connection can be made suggests that something in the intricacies of particle physics’ standard model is not completely understood. The standard model is a subatomic-scale model of the world that illustrates all particles and their interactions, so when intrigues occur, there is reason to be concerned. The study was published in the journal *Physical Review Letters*.

## Duality in Physics

The concept of duality appears in different fields of physics. The particle-wave duality in quantum mechanics is probably the most well-known duality. Light behaves like a wave in the famous double-slit experiment, while light behaves like a particle in Albert Einstein’s Nobel Prize-winning work.

The amazing fact is that light is simultaneously “both and neither of the two.” There are only two ways to look at the light, and each one has its own mathematical description. Both describe the same thing, but with completely different intuitive ideas.

*What we have now found is a similar duality. We calculated the prediction for one scattering process and for another scattering 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 linked, somehow*.

Matthias Wilhelm, Assistant Professor, Niels Bohr International Academy

## Theory and Experiments Go Hand in Hand

The researchers collided many protons at the Large Hadron Collider, and these protons contain many smaller particles, such as gluons and quarks, which are subatomic particles.

Two gluons from distinct protons can interact in a collision, resulting in the creation of new particles like the Higgs particle and intricate patterns in the detectors.

They then mapped how all these patterns appear. The theoretical work done in conjunction with the experiments aimed to describe exactly what happens in mathematical terms to generate an overall formulation and make predictions that can be equated to the experiment results.

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

Matthias Wilhelm, Assistant Professor, Niels Bohr International Academy

Wilhelm adds, “*To our surprise, we found that the results of these two calculations are related. A classical case of duality. Somehow, the answer for how likely it is for one scattering process to happen carries within it the answer for how likely it is for the other scattering process to happen.*”

*The strange thing about this duality is that we don’t know why this relation between the two different scattering processes exists. We are mixing two very different physical properties of the two predictions, and we see the relation, but it is still a bit of a mystery wherein the connection lies*.

Matthias Wilhelm, Assistant Professor, Niels Bohr International Academy

## The Duality Principle and the Application of it

The two should not be linked, as per the current understanding, but the only proper response to the discovery of this remarkable duality is to explore further.

Surprises always indicate that there is something beyond understanding. No new, sensational particles have been unearthed since the discovery of the Higgs particle in 2012. The researchers intend to detect new physics by making very accurate predictions on what is expected to happen, and later compare them with very precise measurements of what nature shows, and analyze for any deviations there.

Both experimentally and theoretically, a high level of precision is required. However, greater precision necessitates more difficult calculations.

Wilhelm states, “*So where this could be leading is working in order to see if this duality can be used to get a sort of “mileage” out of it, because one calculation is simpler than the other—but still it gives the answer to the more complicated calculation*.”

“*So if we can settle for using the simple calculation we may use the duality to answer the question that would otherwise require more complicated calculations—But then we really need to understand the duality. It is important to note, though, that we are not there yet. But usually, the questions that arise from unexpected behavior of things are a lot more interesting than an orderly and expected outcome*,” concludes Wilhelm.

**Journal Reference:**

Dixon, L. J., *et al*. (2022) Folding Amplitudes into Form Factors: An Antipodal Duality. *Physical Review Letters*. doi.org/10.1103/PhysRevLett.128.111602.

Source: https://nbi.ku.dk/english/