The 'flicker' of gluons in subatomic smashups

Scientists exploring the dynamic behavior of particles emerging from subatomic smashups at the Relativistic Heavy Ion Collider a U.S. Department of Energy Office of Science User Facility for nuclear physics research at DOE's Brookhaven National Laboratory are increasingly interested in the role of gluons. These glue-like particles ordinarilybind quarks within protons and neutrons, and appear to play an outsized role in establishing key particle properties.
It is very accurately known howlarge the average gluon density is inside a proton," Mäntysaari said. "What is not known is exactly where the gluons are located inside the proton. We model the gluons as located around the three valance quarks. Then we control the amount of fluctuations represented in the model by setting how large the gluon clouds are, and how far apart they are from each other."The fluctuations represent the behavior of gluons in particles accelerated to high energies as they are in colliders like RHIC and the LHC. Under those conditions, the gluons are virtual particles that continuously split and recombine, essentially flickeringin and out of existence like fireflies blinking on and off in the nighttime sky.Scientists would like to know if and how these fluctuations affect the behavior of the particles created when protons collide with heavy nuclei, like the gold ions accelerated at RHIC. Data from RHIC's proton-gold collisions, and from the LHC's proton-lead collisions, have shown evidence of"collective phenomena"-particles emergingwith some "knowledge" of one another and in some preferred directions rather than in a uniform fashion. In RHIC and LHC smashups of two large particles (gold-gold or lead-lead), this collective behavior and direction-dependent flow has been explained by the liquid state of quarks and gluons-the "perfect liquid" quark-gluon plasma (QGP)-created in these collisions. But collisions of tiny protons with the larger nuclei aren't supposed to create QGP. And the current understanding of the QGP can't completely explain the experimental results.