Experts at the University of Adelaide are trying to unlock the secrets of dark matter, which makes up 84 percent of the universe’s, but little is known about it. The researchers use a new tool that could signal the existence of a new particle.
“Dark matter is five times more abundant than the visible matter that physicists have explored so successfully and of which we are composed. We don’t know what kind of particle it forms, but we, along with a large number of people in the world, want to understand this,” Anthony Thomas, senior professor of physics at this Australian university, explained in a statement.
“We try to solve the problem of understanding one of the great challenges facing modern science: how to find what kind of particles dark matter is made of,” he added.
Anthony Thomas is part of the team at the ARC Center of Excellence for Dark Matter Particle Physics, whose goal is to discover more about this mysterious substance.
A key focus is the Active Bottom Rejection Sodium Iodide Experiment (Sabre) being built in a new laboratory at a former gold mine one kilometer below ground in Stawell, Victoria. It is being built in collaboration with researchers from Australia, Europe and the United States and hopefully in a few years will shed light on this question.
Thomas’ latest work with colleague Xuangong Wang and Anthony Williams, from the University of Adelaide’s School of Physical Sciences, published in the journal Physical Review Letters, explores the possibility that dark matter exists in the form of a massive dark photon. .
Parity Violation Process
“We are exploring the discovery potential of a new tool, parity-violating electron scattering, made possible by an upgrade at the Thomas Jefferson National Accelerator (JLab) facility in the United States,” he said.
“Parity violation is like looking at the difference between what happens in the lab and what happens when you look at the experiment in a mirror. The differences are very small, usually less than one part per million, but precise measurements allow us to observe this, and use it as a sign of the existence of this new particle. We found a mysterious result for the size of a lead nucleus that can be explained if there is a particular new dark matter particle, the dark photon.
“New experiments in which changes in predictions without dark matter could be changed by up to 5 percent, and the difference provides direct evidence for this type of dark matter.”
Insights into this new particle from Thomas’ work may help explain a surprising discrepancy that has been inferred from experiments at JLab between the neutron density in a parent nucleus and that predicted by nuclear structure theory.
“Vital proof of the existence of such a particle could be provided by future experiments on the behavior of electrons, positrons and deuterons,” he said.
“Visible matter is just the tip of the iceberg. With a better understanding of the dark, the part below the surface, we will shed light on the secrets of the universe.”
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