Research at Hokkaido University has found that elusive particles called neutrinos can interact with photons - the elementary particles of light and other electromagnetic radiation - in a way that has not been detected before. The research results of Hokkaido University Honorary Professor Kenzo Ishikawa and his colleague Yutaka Tobei, a lecturer at Hokkaido University of Science and Technology, were published in the journal PhysicsOpen.
"Our findings are important for understanding the quantum mechanical interactions of some of the most fundamental particles of matter. They may also help reveal details of currently poorly understood phenomena in the Sun and other stars," Ishikawa said.
Neutrinos are one of the most mysterious fundamental particles of matter. Because neutrinos barely interact with other particles, they are extremely difficult to study. They are electrically neutral and have almost no mass. Yet they are abundant, with vast amounts of neutrinos streaming out of the Sun, through the Earth, and even through ourselves, with almost no effect. Learning more about neutrinos is important for testing and refining our current understanding of particle physics, known as the Standard Model.
"Under normal 'classical' conditions, neutrinos do not interact with photons," Ishikawa explains. "However, we have revealed how neutrinos and photons can interact in uniform magnetic fields on extremely large scales - as large as 103 kilometers - where such magnetic fields appear The form of matter around a star is called plasma. Plasma is an ionized gas, which means that all of its atoms have gained more or less electrons, making them either negatively or positively charged ions, rather than the neutral atoms they might be under everyday conditions on Earth."
Weak electric Hall effect and its impact
The interaction the researchers describe involves a theoretical phenomenon called the electroweak Hall effect. This is the interaction between electricity and magnetism under extreme conditions, where the two basic forces of nature - the electromagnetic force and the weak force - merge into weak electricity. This is a theoretical concept expected to apply only in the extremely high-energy conditions of the early universe or in collisions at particle accelerators.
The research yielded a mathematical description of this unexpected neutrino-photon interaction, known as the Lagrangian. It describes all known information about the energy state of the system.
"In addition to helping us understand fundamental physics, our study may help explain the mystery of coronal heating," Ishikawa said. "This is a long-standing mystery involving the mechanism by which the sun's outermost atmosphere - the corona - becomes much hotter than the sun's surface. Our work shows that interactions between neutrinos and photons release energy that heats the corona."
In his concluding remarks, Ishikawa expressed his team's desire: "We now hope to continue our work and find deeper insights, especially into the energy transfer between neutrinos and photons under these extreme conditions."