Going against the flow: Revealing the QCD degrees of freedom in hadronic collisions

• DOI: 10.48550/arxiv.2409.16093
• Publication Date: 2024-09-24
• Authors: Christian Bierlich; P. Christiansen; Gösta Gustafson; Leif Lönnblad; Robin Törnkvist; Korinna Zapp
• Keywords: Nuclear Theory (nucl-th); High Energy Physics - Phenomenology; High Energy Physics - Phenomenology (hep-ph); Nuclear Theory; FOS: Physical sciences

In collisions between heavy nuclei, such as those at the Large Hadron Collider (LHC) CERN, hydrodynamic models have successfully related measured azimuthal momentum anisotropies to transverse shape of collision region. For an elliptically shaped interaction area, pressure gradient is greater along minor axis, resulting in increased particle that direction - a phenomenon known positive elliptic flow. this paper, we demonstrate smaller systems, proton-proton and peripheral ion-ion collisions, microscopic for final state interactions, can produce where flow negative is, largest major contrary predictions. We present results from two distinct models: one based on repulsion string-like fields another effective kinetic theory. Negative solid prediction string model while theory it linked finite range. Consequently, experimental determination sign flow, will provide novel insights into degrees freedom governing strong nuclear interactions high-energy way which they interact.