Neutrinos (May Dance With Photons in the Atmosphere of Stars)

[Recusant]

I looked for a neutrino thread to add this one to, but the site search isn't great, so here's one. Hat-tip to the illustrious headline editor who sticks by their guns and gets the story wrong.

"Neutrinos: 'Ghost Particles' Can Interact With Light After All" | Science Alert

Neutrinos, the tricky little particles that just stream through the Universe like it's virtually nothing, may actually interact with light after all.

According to new calculations, interactions between neutrinos and photons can take place in powerful magnetic fields that can be found in the plasma wrapped around stars.

It's a discovery that could help us understand why the Sun's atmosphere is so much hotter than its surface, say Hokkaido University physicist Kenzo Ishikawa and Yutaka Tobita, a physicist from Hokkaido University of Science – and, of course, to study the mysterious ghost particle in greater detail.

"Our results are important for understanding the quantum mechanical interactions of some of the most fundamental particles of matter," Ishikawa says. "They may also help reveal details of currently poorly understood phenomena in the Sun and other stars."

Neutrinos are among the most abundant particles in the Universe, second only to photons. But they keep to themselves, mostly. Neutrinos are almost without mass, and barely interact with matter. To a neutrino, the Universe is as nothing – shadows or specters, through which they pass with ease. Billions of neutrinos are passing through you right now, like teeny tiny ghosts.

[. . .]

The work of Ishikawa and Tobita is theoretical, using mathematical analysis to determine the circumstances under which neutrinos can interact with electromagnetic quanta – photons. And they discovered that highly magnetized plasma – gas that is either positively or negatively charged, due to the subtraction or addition of electrons – offers the right environment.

"Under normal 'classical' conditions, neutrinos will not interact with photons," Ishikawa says.

"We have revealed, however, how neutrinos and photons can be induced to interact in the uniform magnetic fields of the extremely large scale – as large as 10³ km – found in the form of matter known as plasma, which occurs around stars."

Previously, Ishikawa and Tobita explored the possibility that a theoretical phenomenon known as the electroweak Hall effect could facilitate neutrino interactions in the solar atmosphere. This is when, under extreme conditions, two of the Universe's fundamental interactions, electromagnetism and the weak force, sort of smoosh together into one.

Under electroweak theory, neutrinos could interact with photons, the researchers found. If a star's atmosphere could produce the right kind of environment for the electroweak Hall effect, these interactions could be taking place there.

[Continues . . .]

The paper is open access:

"Topological interaction of neutrino with photon in a magnetic field — Electroweak Hall effect" | Physics Open

Abstract:

The effective interaction of a neutrino with a photon in magnetized plasma is obtained from a strong field expansion in the electroweak standard model. The interaction is expressed by a Chern–Simons form of the neutrino current and the electromagnetic vector potential of the coupling strength proportional to 𝑛𝑒/𝐵 × 𝑒𝐺_𝐹. The derivation of the interaction Lagrangian and its properties are presented.