Scientists have taken a closer look at quark-gluon plasma, the ultra-hot state of matter created when atomic nuclei collide at nearly the speed of light. According to ScienceDaily, the material behaves like an almost perfect fluid and gives researchers a way to study conditions similar to those just after the Big Bang.
A team led by Fudan University physicists Yu-Gang Ma and Xu-Guang Huang focused on acceleration inside the plasma, an effect that has received less attention than swirling motion and electromagnetic fields. They used the AMPT and UrQMD particle transport models along with a Gaussian smearing method to turn particle distributions into continuous fluid-like fields.
The researchers examined collision energies from 3.5 GeV to 2.76 TeV and found that peak proper acceleration can reach several hundred MeV at both low and high energies. Their simulations showed the strongest transverse acceleration near the outer edge of the fireball, where pressure drops quickly and enthalpy density is low.
At lower energies, nuclear stopping can slow the matter down and produce deceleration of up to about 500 MeV. At the highest energies, the nuclei pass through each other so quickly that they create brief acceleration pulses in the newly formed plasma, according to the study.
The team says acceleration may do more than shape motion. It could affect the plasma’s phase structure, transport properties, and particle spin alignment, and the researchers plan to look for experimental signals such as hyperon spin polarization in future work.
