Particle observed switching between matter and antimatter, physicists discover

Oxford Physicists Find Charm Mesons Switching Between Matter and Antimatter, Challenging Universe’s Origin Mystery

TL;DR

Physicists at Oxford University have discovered that charm mesons, subatomic particles created at the Large Hadron Collider, can oscillate between matter and antimatter states. This revelation highlights a tiny mass difference of 0.0000…01 grams between these states. The finding could explain why the universe didn’t annihilate after the Big Bang, suggesting charm mesons might convert to matter more often than to antimatter. This could offer crucial insights into the imbalance between matter and antimatter in the universe, challenging existing theories about its origin.

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Oxford physicists examining data from the Large Hadron Collider have discovered that a subatomic particle can switch between matter and antimatter. This finding suggests that a minuscule weight difference between two particles may have prevented the universe from annihilating itself shortly after its inception.

Antimatter is essentially the “evil twin” of regular matter, differing only in its charge. When matter and antimatter particles meet, they annihilate each other in a burst of energy.

Some particles, such as photons, are their own antiparticles, while others can exist in a mixed state of both matter and antimatter simultaneously, thanks to the quantum principle of superposition (famously demonstrated by Schrödinger’s cat thought experiment). This means these particles oscillate between being matter and antimatter.

Now, a new particle, the charm meson, has been added to this unique group. Normally, a charm meson is composed of a charm quark and an up antiquark, while its antimatter counterpart is made of a charm antiquark and an up quark. Typically, these states are distinct, but the new research shows that charm mesons can spontaneously switch between them.

The key to this discovery is an exceedingly tiny mass difference between the two states, specifically 0.00000000000000000000000000000000000001 grams.

This precise measurement was obtained from data collected during the Large Hadron Collider’s second run by physicists at Oxford University. Charm mesons are created in proton-proton collisions at the LHC, and they usually decay into other particles within a few millimeters of travel.

By analyzing charm mesons that travel varying distances before decaying, the team determined that mass differences are a major factor in whether a charm meson transforms into an anti-charm meson.

This minute discovery could have profound implications for our understanding of the universe. The Standard Model of particle physics suggests that the Big Bang should have produced equal amounts of matter and antimatter, which would have annihilated each other, leaving the universe empty. Since this did not happen and matter came to dominate, what caused this imbalance?

One hypothesis that the new discovery raises is that particles like the charm meson will transition from antimatter to matter more often than they turn from matter to antimatter. Investigating whether that’s true – and if so, why – could be a major clue that busts open one of the biggest mysteries of science.

The study has been submitted to the journal Physical Review Letters, and is currently available on the preprint server arXiv.

Sources: Oxford University, CERN