Physics

Particle seen switching between matter and antimatter at CERN

Particle seen switching betwee...
Two particles ready to collide to one another artistic image
Two particles ready to collide to one another artistic image
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Two particles ready to collide to one another artistic image
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Two particles ready to collide to one another artistic image
An illustration highlighting the difference in mass between two versions of the charm meson
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An illustration highlighting the difference in mass between two versions of the charm meson

A subatomic particle has been found to switch between matter and antimatter, according to Oxford physicists analyzing data from the Large Hadron Collider. It turns out that an unfathomably tiny weight difference between two particles could have saved the universe from annihilation soon after it began.

Antimatter is kind of the “evil twin” of normal matter, but it’s surprisingly similar – in fact, the only real difference is that antimatter has the opposite charge. That means that if ever a matter and antimatter particle come into contact, they will annihilate each other in a burst of energy.

To complicate things, some particles, such as photons, are actually their own antiparticles. Others have even been seen to exist as a weird mixture of both states at the same time, thanks to the quantum quirk of superposition (illustrated most famously through the thought experiment of Schrödinger’s cat.) That means that these particles actually oscillate between being matter and antimatter.

And now, a new particle has joined that exclusive club – the charm meson. This subatomic particle is normally made up of a charm quark and an up antiquark, while its antimatter equivalent consists of a charm antiquark and an up quark. Normally those states are kept separate, but the new study shows that charm mesons can spontaneously switch between the two.

What ultimately gave away the secret was that the two states have slightly different masses. And we mean “slightly” in the extreme – the difference is just 0.00000000000000000000000000000000000001 grams.

This incredibly precise measurement was fished out of data gathered during the Large Hadron Collider’s second run, by physicists at Oxford University. Charm mesons are produced at the LHC in proton-proton collisions, and normally they only travel a few millimeters before they decay into other particles.

By comparing the charm mesons that tend to travel further versus those that decay sooner, the team identified differences in mass as the main factor that drives whether a charm meson turns into an anti-charm meson or not.

An illustration highlighting the difference in mass between two versions of the charm meson
An illustration highlighting the difference in mass between two versions of the charm meson

This absolutely tiny find could have gigantic implications for the universe. According to the Standard Model of particle physics, the Big Bang should have produced matter and antimatter in equal amounts, and over time that all would have collided and annihilated, leaving the cosmos a very empty place. Obviously that didn’t happen, and somehow matter came to dominate, but what caused that 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

10 comments
10 comments
Joe
Maybe the decaying particle weight lose transition into the next state , balance the collision impact on both planes.
piperTom
Yes, I WAS triggered by that ".00000000000000000000000000000000000001" number; then I saw that it's grams. Grams! How about giving it as 5E-3 EV? Five thousandths of an EV is still pretty small, but that description doesn't make us count. And speaking of drama, it's reported here that the mesons "normally ...only travel a few millimeters before they decay into other particles." That is what happened here. SO, is there missing mass? If so, then THAT is the big story. O'wise the story is that some VERY short lived particles are unbalanced. And I missed the connection to an over abundance of fermions, the type of particle that can persist for 13.8 billion years.
Tacky-on
It seems like if you build the accelerator, you will find it. Sort of the Field of Dreams approach to quantum physics. Endless reductionism to find whatever particle you need to make the math work.

At this point there is an old joke that seems to explain reality better.

Mind over matter. Doesn't matter, never mind.
Ray6969
I've worked with a few physicist in my career. Some from NASA, some from other accelerators, some from Fermi NAL in Batavia, Il. and even some that work on the LHC at Cern. Great guys but a little weird at times. ;)
Ron
Hopefully the Large Hadron Collider never has an Uh-Oh moment, I can appreciate the science but considering the past history of atomic research this sort of playing "God" with a great big powerful toy scares the hell out of me.
Lamar Havard
I was hoping the discoverer would've named it the Gideon particle.
RG Lyons
Years ago, I had a dream that the Higgs boson caused particles to swap from matter to antimatter by altering a particle's mass. Then I forgot about it in another dream.
wolf0579
@Lamar Havard

I've known some of the people that built a part of the LHC. They are generally NOT the religious type. it seems that the more science education you accumulate, you become less inclined to believe the book of forgeries and hoax that is the x-stian bible.
aki009
So while resonating between the two states, what happens to the energy in the state with the lesser mass??
MQ
If the lesser mass particle isn't a rounding error, there must be madd conversion energy emitted meaning that the state can't revert - without regaining the energy. Find the missing photon.

Schroedingers Catze, merely demonstrates the uncertainty associated with any hypothesis before diligent enquiry is made. Rather than demonstrating with superposition.... Is that also just a mind game?? And it was so, science is so unpredictable at times, the why may never be understood but the discovery of what is fascinating. "When you think you understand, you are wrong."