Theoretical Studies of Particles and Strings
Lead Research Organisation:
University of Oxford
Department Name: Oxford Physics
Abstract
Our ultimate aim is to understand the nature of matter & forces, and the content & evolution of the universe as a whole. One of the most intriguing features of reality is what the physicist Eugene Wigner called "the unreasonable effectiveness of mathematics in the natural sciences" in being able to provide an accurate & predictive description of observed phenomena. As theoretical physicists we exploit this by motivating and constructing mathematical models of physical systems, for which we also devise experimental tests whenever possible, as these are ultimately the arbiter of truth.
Our focus is on the fundamental constituents and interactions of matter, both within the Standard Model (SM) of the strong, weak & electromagnetic interactions, and searching for understanding of phenomena not explained by the SM, such as quantum gravity.
Experimentally, there are many ways of attempting to understand these fundamental constituents and interactions. Fundamental particles can be produced and studied at accelerators like the Large Hadron Collider (LHC) at CERN. It is also possible to learn about them from the cosmic rays produced in extreme astrophysical environments and through cosmological and gravitational wave signatures left over from the early stages of the universe.
Our theoretical work accompanies and complements such experimental work in multiple ways:
1. We determine the experimental and observational consequences of concrete theories of fundamental particles & interactions that attempt to explain some of the major open mysteries such as the nature of dark matter. We consider a broad range of potential signatures, including gravitational waves, high-energy cosmic rays, phenomena at colliders such as the LHC and manifestations in a range of highly sensitive experiments based on new quantum technologies. We also examine to what extent known phenomena, such as black-hole production, could explain mysteries such as dark matter.
2. We explore string theory, which offers the possibility of understanding how to reconcile quantum mechanics and gravity. This provides an extremely rich theoretical framework, offering many avenues to study. For example, string theory naturally involves many more dimensions than four spacetime dimensions that we are familiar with and we attempt to understand how those dimensions can be folded up so as to be imperceptible to us. We explore internal consistency conditions on theories of quantum gravity, and we devise techniques for calculations within string theory. Machine learning is used to help navigate our way through the huge number of spacetime geometries that string theory offers.
3. Both known and proposed new theories of fundamental interactions often involve regimes where the underlying particles interact strongly. This is the case, for example, for the well established theory of the strong force, quantum chromodynamics. The regime of strong interactions is one where it is challenging to relate the characteristics of the underlying theory to potential experimental observations, and part of our effort is devoted to devising methods to better understand the consequences of strongly-interacting theories, both within string theory, which offers numerous frameworks to study strong interactions, as well as with a view to phenomenological applications.
4. We also put considerable effort into making predictions for theories that are weakly interacting. This is especially important in order to draw conclusions from the high-precision data about the Higgs boson and other particles being studied at CERN's LHC. The basic principles for how to make predictions for weakly interacting theories are well established, however putting them into practice brings huge challenges, which we attempt to address through novel mathematical, computational and physics approaches.
Our focus is on the fundamental constituents and interactions of matter, both within the Standard Model (SM) of the strong, weak & electromagnetic interactions, and searching for understanding of phenomena not explained by the SM, such as quantum gravity.
Experimentally, there are many ways of attempting to understand these fundamental constituents and interactions. Fundamental particles can be produced and studied at accelerators like the Large Hadron Collider (LHC) at CERN. It is also possible to learn about them from the cosmic rays produced in extreme astrophysical environments and through cosmological and gravitational wave signatures left over from the early stages of the universe.
Our theoretical work accompanies and complements such experimental work in multiple ways:
1. We determine the experimental and observational consequences of concrete theories of fundamental particles & interactions that attempt to explain some of the major open mysteries such as the nature of dark matter. We consider a broad range of potential signatures, including gravitational waves, high-energy cosmic rays, phenomena at colliders such as the LHC and manifestations in a range of highly sensitive experiments based on new quantum technologies. We also examine to what extent known phenomena, such as black-hole production, could explain mysteries such as dark matter.
2. We explore string theory, which offers the possibility of understanding how to reconcile quantum mechanics and gravity. This provides an extremely rich theoretical framework, offering many avenues to study. For example, string theory naturally involves many more dimensions than four spacetime dimensions that we are familiar with and we attempt to understand how those dimensions can be folded up so as to be imperceptible to us. We explore internal consistency conditions on theories of quantum gravity, and we devise techniques for calculations within string theory. Machine learning is used to help navigate our way through the huge number of spacetime geometries that string theory offers.
3. Both known and proposed new theories of fundamental interactions often involve regimes where the underlying particles interact strongly. This is the case, for example, for the well established theory of the strong force, quantum chromodynamics. The regime of strong interactions is one where it is challenging to relate the characteristics of the underlying theory to potential experimental observations, and part of our effort is devoted to devising methods to better understand the consequences of strongly-interacting theories, both within string theory, which offers numerous frameworks to study strong interactions, as well as with a view to phenomenological applications.
4. We also put considerable effort into making predictions for theories that are weakly interacting. This is especially important in order to draw conclusions from the high-precision data about the Higgs boson and other particles being studied at CERN's LHC. The basic principles for how to make predictions for weakly interacting theories are well established, however putting them into practice brings huge challenges, which we attempt to address through novel mathematical, computational and physics approaches.
