Discovering Axions: A Potential Solution to One of Physics’ Most Perplexing Mysteries.

One of the most outstanding mysteries in physics today is what scientists refer to as the “strong cerebral palsy problem.” Driven by the puzzling phenomenon that neutrons do not interact with electric fields despite being made of quarks — smaller fundamental particles that carry an electric charge — the powerful CP problem calls into question the Standard Model of physics, or the set of theories that scientists use to explain the laws of nature. for years.

A team led by theoretical physicists at the University of Minnesota Twin Cities has discovered a new way to search for axions, virtual particles that could help solve this mystery. In collaboration with experimental researchers at the Fermilab National Accelerator Laboratory, the new strategy opens up previously unexplored opportunities for physicists to discover axions in particle collider experiments.

The researchers’ paper was published and presented as an editor’s suggestion in Physical review letters.

“As particle physicists, we’re trying to advance our best understanding of nature,” said Zhen Liu, co-author of the paper and assistant professor in the University of Minnesota’s College of Physics and Astronomy. “Scientists have had tremendous success in the past century finding elementary particles through well-established theoretical frameworks. Therefore, it is very puzzling why neutrons do not couple to electric fields because in our known theory, we would expect them to. If we discover axions, it will be a major advance in our fundamental understanding to the structure of nature.”

One of the primary means of studying subatomic particles, and possibly discovering new ones, is collider experiments. Essentially, scientists force beams of particles to collide—and when they collide with each other, the energy they produce creates other particles that pass through a detector, allowing researchers to analyze their properties.

The method proposed by Liu and his team involves measuring the “decay” product — or what happens when an unstable heavy particle turns into several lighter particles — from hypothetical axes to two known particles that are essentially the heavier version of an electron. By working backwards from the muon trajectories in the detector to reconstruct such decays, the researchers believe they have a chance to locate the axion and prove its existence.

“With this research, we are expanding ways in which we can search for an axion,” said Raymond Kue, a co-author of the paper and a postdoctoral researcher in the University of Minnesota College of Physics and Astronomy and the William Fine Institute for Theoretical Physics. “People have never used axion decay into muons as a way to search for an axion particle in neutrino or collider experiments before. This research opens up new possibilities to pave the way for future endeavors in our field.”

Liu and Co., along with University of Minnesota physics and astronomy postdoctoral researcher Kun Feng Liu and UCLA postdoctoral researcher Subhik Kumar, are behind the theoretical part of the research. It’s part of the ArgoNeuT collaboration, which brings together theorists and experimenters from across the country to study particles through experiments at Fermilab.

In this paper, the theoretical team led by the University of Minnesota worked with experimental researchers to conduct axon searches using their new method and existing data from the ArgoNeuT experiment. The researchers plan to use the experimental results to improve their theoretical calculations of the rate of axion production in the future.