For a quark-gluon plasma (QGP) to be created, researchers can use powerful colliders to crush atomic nuclei together.
When an energetic quark travels through a “soup” of “free” quarks and gluons — the quark-gluon plasma (QGP) — non-local quantum effects should cause it to scatter faster and at wider angles (Δθ ) than expected from mere local interactions. Image Credit: Brookhaven National Laboratory.
This so-called “soup” of gluons and quarks, some of the basic building blocks of matter, helped fill the early universe.
Having a track of how high-energy jets of quarks travel via the QGP could disclose data regarding the properties of QGP. The simplest assumption of researchers is that local interactions with the gluons and quarks will deflect such energetic particles.
However, recent theoretical calculations that also consisted of non-local quantum interactions—those interactions beyond the immediate surroundings of the particle—forecast a super-diffusive process. This implies that the complicated interactions happening in QGP deflect quarks quicker and at wider angles compared to what could be described by local interactions alone.
The Impact
Testing such predictions at particle colliders will offer a new vision into the interactions happening between gluons and quarks. Such interactions have been regulated by the powerful nuclear force, one of the four basic forces that govern the universe.
The new theoretical explanation points to the significance of the non-local nature of such quantum interactions.
The study outcome denotes that the description of the QGP as a collection of point-like particles might collapse even at short distances. Also, the breakthrough of the significance of longer-range quantum interactions may provide a new perspective for comprehending why the QGP flows like an almost perfect fluid—a fluid with very low viscosity.
Summary
Researchers utilize particle colliders to recreate a form of early universe matter called a QGP. Tracking how energetic jets of particles pass through the QGP could disclose information regarding its properties.
Based on the theory of strong interactions, early calculations performed denoted the fact that jets would experience a diffusive process that has been caused by random deflections as the energetic particles interacted with the gluons and quarks that compose the plasma—similar to the way pollen particles present on the surface of a pond get “kicked” around by water molecules.
Counter to such early calculations, nuclear theorists at Brookhaven National Laboratory recently found out that including non-local quantum effects—which emerge from long-lived gluon fluctuations—forecasts considerable deviations from the anticipated diffusion pattern in QGP.
Including such non-local effects forecasts that energetic jets will experience a super-diffusive process, thereby widening the angle of the jet faster compared to what the local interactions alone could explain.
The predictions could be tested by tracking energetic jets in the QGP made in high-energy heavy ion collisions at the Relativistic Heavy Ion Collider (a Department of Energy user facility at Brookhaven National Laboratory) and the Large Hadron Collider in Europe.
This study was financially supported by the Department of Energy Office of Science, Office of Nuclear Physics, and the National Science Foundation.
Journal Reference:
Paul, C., et al. (2023) Universality aspects of quantum corrections to transverse momentum broadening in QCD media. Journal of High Energy Physics. doi.org/10.1007/jhep09(2022)023.