Michael Reichenberg Ashby

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Project title: New applications of the classical double copy

Supervisor: Professor Chris D. White

The mathematical frameworks used to describe fundamental forces—general relativity for gravity and gauge theory for the electromagnetic and strong/weak nuclear forces—are built from different perspectives and expressed using very different field variables. Yet, in specific circumstances they reveal unusual similarities which provide powerful tools for calculations and prompt questions about their internal structures.

Specifically, when considering scattering observables, it is sometimes possible to take an amplitude from gauge theory and recycle its components to build a gravity amplitude using what is known as the double copy prescription. This prescription has recently been expanded beyond individual amplitudes to map a limited number of algebraically special classical solutions in gauge theory and gravity to one another. For example, the Schwarzschild black hole solution can be constructed in this way as the double copy of the Coulomb charge in gauge theory.

However, much remains unknown about the true extent of this formalism to map arbitrary solutions, or what the general prescription is to make these mappings apparent. The freedom to choose gauges, coordinates, and classical field variables works to obfuscate the mechanism of the double copy, making it difficult to find precise, general statements about its remit and geometrical interpretation.

My project aims to investigate aspects of the classical double copy, using alternative formulations of gravity and gauge theory to better understand its mechanism as well as how it can be applied as a calculational tool across a range of fields.

Funding: Science and Technology Facilities Council (STFC)

Research