"We're pushing to the most extremes in fluid dynamics,” Noronha-Hostler says. “Not only do we have something that is moving at the speed of light and at the highest temperatures known to humanity, but it looks like we are going to be able to answer ‘What is the smallest d...

They went looking for collisions between photons and nuclei, called photonuclear collisions, in data collected during the lead-ion runs at the LHC. These runs have happened in the few weeks just before the LHC’s winter shutdown each year that the LHC has been in operation.

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After collecting and analyzing the data, Seidlitz, Perepelitsa and their colleagues saw a particle-flow signature characteristic of a quark-gluon plasma. 

The finding alone is not enough to prove the formation of a quark-gluon plasma, but it’s a first clue. “There are alway...

Although they have known for years they could produce small amounts of quark-gluon plasma in collisions between heavy ions, this is the first time scientists have reported possible evidence of quark-gluon plasma in the aftermath of a collision between the nucleus of a heavy ion and a mass...

When two lead nuclei collide at high energy inside the LHC, the gluons can lose their grip, causing the protons and neutrons to melt and merge into a quark-gluon plasma. The now-free quarks and gluons pull on each other, holding together as the plasma expands and cools. 

Ev...

Luckily, photonuclear collisions have a special asymmetrical shape due to the momentum differences between the tiny photon and the massive lead ion: “It’s like a truck hitting a trash can,” Seidlitz says. “All the debris from the collision will move in the direction of the truck.”

Seidlitz ...

It was the positron, the first predicted particle of antimatter. In 1932, Caltech physicist Carl Anderson discovered the particle, and later physicists spotted the annihilation process Dirac had predicted as well.

When matter and antimatter meet, th...

For now, the exact mechanism that may be causing this quark-gluon plasma signature within photonuclear collisions remains a mystery. Whatever is going on, Noronha-Hostler says figuring out these collisions could be an important step in quark-gluon plasma research. 

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Perepelitsa and his colleagues suspect that the collisions they’ve observed, in which photons appear to be colliding with lead nuclei and creating a small amount of quark-gluon plasma, are not actually collisions between nuclei and photons. Instead, they’re collisions between nuc...

During the lead-ion runs at the LHC, nuclei aren’t the only things colliding. Because they have a positive charge, lead nuclei carry strong electromagnetic fields that grow in intensity as they accelerate. Their electromagnetic fields spit out high-energy photons, which can also collide—a fairly ...