September 4, 2015

‘Littlest’ quark-gluon plasma revealed by physicists using Large Hadron Collider

CMS detector. Photo courtesy CERN.

(September 4, 2015)  Researchers at the University of Kansas working with an international team at the Large Hadron Collider have produced quark-gluon plasma — a state of matter thought to have existed right at the birth of the universe — with fewer particles than previously thought possible.

The material was discovered by colliding protons with lead nuclei at high energy inside the supercollider’s Compact Muon Solenoid detector. Physicists have dubbed the resulting plasma the “littlest liquid.”

“Before the CMS experimental results, it had been thought the medium created in a proton on lead collisions would be too small to create a quark-gluon plasma,” said Quan Wang, a KU postdoctoral researcher working with the team at CERN, the European Organization for Nuclear Research. Wang performed key analysis for a paper about the experiment recently published in APS Physics.

“Indeed, these collisions were being studied as a reference for collisions of two lead nuclei to explore the non-quark-gluon-plasma aspects of the collisions,” Wang said. “The analysis presented in this paper indicates, contrary to expectations, a quark-gluon plasma can be created in very asymmetric proton on lead collisions.” The unexpected discovery was said by senior scientists associated with the CMS detector to shed new light on high-energy physics.

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