A New Perspective on the Structure of the Quantum Vacuum

The study involved researchers from the Faculty of Physics at the Warsaw University of Technology: Prof. Hanna Zbroszczyk, Prof. Daniel Kikoła, Prof. Jan Pluta, Daniel Wielanek, PhD, Diana Pawłowska, PhD, Ashutosh Pandey, PhD, Srikanta Kumar Tripathy, PhD, Priyanka Roy Chowdhury, MSc,  and Jędrzej Kołaś, MSC.

Analysis of proton–proton collisions revealed the existence of spin correlations between pairs of hyperons, which were shown to originate from virtual quark–antiquark pairs present in the vacuum of quantum chromodynamics (QCD). The observed relative polarization signal, at a level of approximately 18%, constitutes a direct experimental trace of quantum correlations transferred from the vacuum to hadrons formed during the process of quark confinement. Importantly, the effect vanishes for particles separated by large angles, consistent with theoretical predictions regarding decoherence in quantum systems. These results provide a new tool for investigating one of the fundamental problems of modern physics: the relationship between quark confinement, chiral symmetry breaking, and quantum entanglement.

“The so-called ‘pyramid’ of strong-interaction physics connects the micro-world of quarks with macroscopic structures of matter, such as protons and neutrons, as well as with fundamental properties of reality, including quantum entanglement. Understanding the relationships between these levels is one of the key goals of contemporary physics and is essential for explaining the origin of mass and the stability of matter. The fundamental element of this structure is quark confinement—the fact that quarks never appear as free particles but are permanently bound inside hadrons by the strong force,” explains Prof. Hanna Zbroszczyk from the Faculty of Physics at the Warsaw University of Technology.

As Prof. Zbroszczyk adds, an equally important mechanism is dynamical chiral symmetry breaking, which accounts for nearly all the mass of visible matter—far exceeding the contribution from the Higgs mechanism.

“Quantum entanglement is also playing an increasingly important role in describing these phenomena, suggesting deep connections between the structure of the vacuum, quark confinement, and the distribution of quantum information within hadrons. Research in this area brings us closer to answering the fundamental question of how stable and massive matter—of which the Universe is composed—emerges from the simple building blocks of the micro-world,” says Prof. Hanna Zbroszczyk.

This achievement highlights the significant contribution of the STAR team, including researchers from the Faculty of Physics at the Warsaw University of Technology, to advancing research on the fundamental properties of matter under extreme conditions.

The full article can be accessed here: Measuring spin correlation between quarks during QCD confinement.