New light particles: from theory to experiment and observations
Lead Research Organisation:
UNIVERSITY OF OXFORD
Abstract
The visible matter around us, everything from stars to planets to intergalactic dust, accounts for only a small fraction of the total matter in the Universe. The rest consists of a mysterious substance known as dark matter, which interacts at most only extremely weakly with light and is therefore invisible. The nature of dark matter is among the biggest open questions in particle physics.
Meanwhile, we have strong observational evidence that the Universe’s evolution from about one second after the Hot Big Bang follows a “standard” cosmological history, but almost nothing is known about its properties before this. On a logarithmic timescale, this means that roughly half of the Universe’s history remains unknown. The early Universe had an enormous energy density, so any observable traces from that epoch, such as a relic background of gravitational waves, could reveal fundamental particle physics at energies far beyond those achievable in laboratories or colliders.
My research explores the idea that new, extremely low-mass particles that have so far escaped detection could constitute dark matter and might play a dramatic role in the early evolution of the Universe. By developing new theoretical models and large-scale computer simulations utilising modern numerical algorithms, and collaborating closely with experimental and observational teams, my work will help reveal the nature of dark matter and how new low-mass particles could have shaped the Universe’s history.
This effort is intertwined with recent technological advances, including ultra-precise sensors that exploit quantum effects and make it possible to search for particles interacting only extremely weakly with ordinary matter. For the first time, searches are reaching the sensitivity required to detect theoretically well-motivated dark matter candidates such as the QCD axion. However, the possible masses of axions span an enormous range, making experimental searches challenging. I will provide the theoretical guidance needed to focus those searches where a discovery is most likely. I will also investigate new strategies to enhance sensitivity to particles with different properties.
Numerical simulations show that axions can clump together to form extremely dense “axion stars” that drift through space, occasionally passing through our Solar System. I will predict the signals such objects could produce, helping experimental teams design detectors capable of observing them. I will also study how networks of cosmic strings, which are thin filaments of energy predicted by high-energy models such as grand unified theories, could have formed and produced gravitational-wave signals detectable by next-generation observatories. In addition, I will investigate whether an ultra-light axion could explain dark energy and what signatures this might leave in the cosmic microwave background (photons left over from the Hot Big Bang) as well as new mechanisms by which black holes might form in the very early Universe.
Together, these studies will advance our understanding of how the Universe began and what it is made of, linking cutting-edge theory with high-performance computing and ongoing experimental efforts in the UK and beyond.
Meanwhile, we have strong observational evidence that the Universe’s evolution from about one second after the Hot Big Bang follows a “standard” cosmological history, but almost nothing is known about its properties before this. On a logarithmic timescale, this means that roughly half of the Universe’s history remains unknown. The early Universe had an enormous energy density, so any observable traces from that epoch, such as a relic background of gravitational waves, could reveal fundamental particle physics at energies far beyond those achievable in laboratories or colliders.
My research explores the idea that new, extremely low-mass particles that have so far escaped detection could constitute dark matter and might play a dramatic role in the early evolution of the Universe. By developing new theoretical models and large-scale computer simulations utilising modern numerical algorithms, and collaborating closely with experimental and observational teams, my work will help reveal the nature of dark matter and how new low-mass particles could have shaped the Universe’s history.
This effort is intertwined with recent technological advances, including ultra-precise sensors that exploit quantum effects and make it possible to search for particles interacting only extremely weakly with ordinary matter. For the first time, searches are reaching the sensitivity required to detect theoretically well-motivated dark matter candidates such as the QCD axion. However, the possible masses of axions span an enormous range, making experimental searches challenging. I will provide the theoretical guidance needed to focus those searches where a discovery is most likely. I will also investigate new strategies to enhance sensitivity to particles with different properties.
Numerical simulations show that axions can clump together to form extremely dense “axion stars” that drift through space, occasionally passing through our Solar System. I will predict the signals such objects could produce, helping experimental teams design detectors capable of observing them. I will also study how networks of cosmic strings, which are thin filaments of energy predicted by high-energy models such as grand unified theories, could have formed and produced gravitational-wave signals detectable by next-generation observatories. In addition, I will investigate whether an ultra-light axion could explain dark energy and what signatures this might leave in the cosmic microwave background (photons left over from the Hot Big Bang) as well as new mechanisms by which black holes might form in the very early Universe.
Together, these studies will advance our understanding of how the Universe began and what it is made of, linking cutting-edge theory with high-performance computing and ongoing experimental efforts in the UK and beyond.
Organisations
People |
ORCID iD |
| Edward Hardy (Principal Investigator / Fellow) |