Two-loop scattering amplitudes for high precision LHC physics

Navn på bevillingshaver

Christian Brønnum-Hansen


DKK 820,000




Internationalisation Fellowships


The smallest building blocks of the universe, the elementary particles, are classified in the Standard Model of particle physics. This model also defines how these elementary particles interact with each other. The spectrum of elementary particles and their interactions are being studied at the Large Hadron Collider (LHC). My research is in the field of theoretical particle physics and aims to increase the precision in Standard Model predictions for particle collision experiments. My project is particularly focused on collision processes involving the heaviest elementary particles, such as the production of single top quarks. The complexity of such calculations requires insight into the structure of the underlying mathematics as well as a high degree of automation on computers.


Particle physics has entered an era of high precision measurements. The data collected from proton collisions in the Large Hadron Collider (LHC) continues to be analysed in search for discrepancies with theoretical predictions from the most successful theory of particle physics, the Standard Model. This theory has shown incredible predictive power and has foreseen the existence of several particles, yet it fails to address open questions such as the nature of dark matter and neutrino masses. With the large quantities of data collected at the LHC, experimental uncertainties are shrinking. Keeping theoretical and experimental uncertainties in line is an important challenge for the particle physics community since any discrepancy could be a sign of new discoveries.


The probability for a specific particle collision outcome depends on a mathematical object known as the scattering amplitude. The calculation of a scattering amplitude is done with a certain target precision. Together with my collaborators, I am developing a numerical framework for calculation of scattering amplitudes involving massive particles. Using our method we have performed computations that are currently beyond the reach of analytic approaches. While this framework has already produced promising results, we are hopeful that yet more complicated processes can be studied using our approach. Furthermore, we will continue our investigations with the aim of converting the computed scattering amplitudes into physical predictions.

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