Physicists Observe Particles Switch Between Matter and Antimatter

A team led by physicists from Oxford University analyzed data from the Large Hadron Collider (LHC) and discovered that a subatomic particle can switch between matter and antimatter, a report by New Atlas explained.

Antimatter, which is differentiated by having the opposite charge to normal matter, is composed of the antiparticles of normal matter. Some particles oscillate between being matter and antimatter via superposition, as illustrated by the thought experiment of Schrödinger’s cat.

In a world-first discovery, it was found that the charm meson, a subatomic particle made out of a charm quark and an antiquark, can travel as a mixture of their particle and antiparticle states, all the while spontaneously switching between the two. The finding is detailed on the preprint server arXiv.

The new discovery was made thanks to stupefyingly precise measurements made by CERN's Large Hadron Collider – both states were differentiated by a minuscule difference in mass of just 0.00000000000000000000000000000000000001 grams. 

Investigating the mystery of matter-antimatter asymmetry

For their research, the physicists at Oxford University pored over data from the LHC's second run. The team set out to investigate between charm mesons that traveled further and those that dissipated sooner — charm mesons are produced during proton-proton collisions at the LHC, and they typically travel a few millimeters before they decay or transform into other particles.

During this investigation, the team identified the tiny differences in mass that decided whether a charm meson ends up as an anti-charm meson or not.

"Tiny measurements like this can tell you big things about the Universe that you didn't expect," Dr. Mark Williams at University of Edinburgh, one of the scientists involved in the research, explained in a press statement.

The discovery, based on its tiny measurements, has potentially enormous implications. The Standard Model of particle physics states that the Big Bang should have produced equal amounts of matter and antimatter. This, in theory, means that both states should have collided and annihilated each other. Instead, matter dominates today over antimatter, in a scientific mystery known as matter-antimatter asymmetry.

By further studying the observed oscillations between the two states of matter, physicists globally may be able to determine whether they were influenced or caused by unknown particles not predicted by the Standard Model.

With plans for the LHC's successor, the Future Circular Collider (FCC), and even talk of a Moon-based hadron collider further in the future, more detailed analysis will build on the charm meson discovery, leading to a more detailed picture of why the universe took on the shape and form we are a part of today.