• For 16 years, scientists have hypothesized the existence of a quasi-particle called a semi-Dirac fermion, named after the mathematician Paul Dirac whose eponymous equation describes these fermions.
• Now a new study claims to have spotted these particles in a semi-metallic material, which conducts electricity like a normal material but exhibits quantum behavior in extreme conditions.
• They found that these particles have no mass when influenced by magnetic fields flowing in a particular direction, but then gain mass when that direction changes.

The subatomic world is home to many mysteries in quantum and classical physics. It is well known that particles act strangely when they cool to absolute zero and begin to exhibit quantum effects. For some particles, this can induce superconductivity, in which an electric current could theoretically exist forever due to a lack of resistance. For other particles, like semi-Dirac fermions, this means fluctuating mass depending on the direction of magnetic fields.

This is the conclusion of a forthcoming article, accepted by the journal Physical examinationwhich reports the first example of these particles theorized in semi-metals (“semi” because they conduct electricity like metals except in extreme conditions). When these semi-metals were subjected to very cold temperatures, close to absolute zero, the researchers noticed that the particles did not flow normally, but instead formed circular movements like the swirls of a river. And remain faithful to the maxim of ‘absolute zero does awesome things,” the material exhibited quantum effects that made the particles act “like a self-reinforcing wave as it circulates around the vortex,” according to New scientist.

To ensure they were correctly analyzing the half-Dirac fermion hypothesis, the research team subjected the semi-metal to various magnetic fields and light frequencies to identify the half-Dirac fermion. particle. However, the strangest behavior they witnessed took place when the team redirected the magnetic fields towards the particles themselves.

“This (particle) is very weird“Yinming Shao said New scientist. “You can imagine walking down the streets of New York and if you go straight, you’re super light, you’re massless. But turn 90 degrees to the east or west and you become super massive.

The team used infrared light to analyze the particle based on the light it reflected – an extremely difficult process, because semimetals contain many other particles that also reflect infrared. These quasi-particles are particularly interesting because they are halfway between normal particles electrons in metals and the type of massless neutrinos that circulate in the cosmos. Further study of these particles could help reveal new insights into various physics, including Coulomb interactions and other quantum phenomena.

For 16 years, scientists have been looking for this hypothetical particle. And now that this has been observed, there is much to learn.

Darren lives in Portland, has a cat, and writes/edits about science fiction and how our world works. You can find his previous work on Gizmodo and Paste if you look hard enough.