After 20 years, jet diffusion wakes detected in quark-gluon plasmas
Boats passing over smooth water form a pair of diffusion wakes behind them veering off at a certain angle. Turbulence occurs along the line directly behind the boat, but the two diffusion waves are at a theoretical angle of 19.5° from the same line, for deep, ideally smooth water.
After 20 years, physicists have observed jet diffusion wakes within quark-gluon plasmas (QGP), a theory first proposed 20 years prior. QGP, the most perfect liquid in the universe, is 200,000 times hotter than the sun's core and was initially considered a plasma before being recognized as a liquid. This discovery, made by the CMS Collaboration at CERN, was published in Physical Review Letters.
Quark-gluon plasmas were the state of the universe for the first few microseconds after the Big Bang and are created by colliding lead nuclei at high energies. Jets of strong force particles, or quarks and gluons, emerge from these collisions and travel through the QGP, creating wakes that were predicted but never observed until now.
The wakes were discovered by analyzing data from millions of collisions, separating the weak signal from background fluctuations. This achievement confirms the theoretical prediction that fast-moving quarks and gluons should create a diffusion wake in the QGP.
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