Understanding helicity structure and the out-of-equilibrium dynamics of anomalies in high-energy QCD

• Applicant: Dr. Niklas Müller
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2018 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 404640738

While it is well know that the most fundamental constituents of the visible matter in the universe are protons and neutron which themselves are comprised of the more fundamental quarks and gluons, the emergence of the properties and symmetries ofthese building blocks of matter is far from being understood.Elementary symmetries have dominated the conceptual progress in physics over the last century, culminating in the successful formulation of the standard model of physics, postulated in the language of gauge theories. Considerations about symmetry and symmetry violation have allowed to derive the basic laws and dynamics of nature, expressed and understood by an elementary set of 'rules' and equations. However an intriguing source of symmetry breaking cannot be perceived from the aforementioned equations: quantum anomalies are tied to the (vacuum) structure of the quantum theory itself and they arise from the passage between the classical to the quantum level of nature.The significance of anomalies out-of-equilibrium is enormous, as they are conjectured to be responsible for the observed matter-antimatter asymmetry of the universe.Despite their deep importance for nature, the experimental verification of quantum anomalies has remained elusive, with the decay of the the neutral pion or the mass of the eta-prime meson being limited exceptions. Only very recently, the empirical verification of the out-of-equilibrium dynamics of anomalies has become possible: a striking experimental manifestation of quantum anomalies out-of-equilibrium is the interplay of topological transitions, such as sphalerons, and large magnetic fields in high-energy heavy ion collisions via the Chiral Magnetic Effect (CME).Many other properties of the fundamental constituents of matter are elusive, a key example being the origin of the protons spin, of which only roughly 30% can be experimentally traced to its constituents, quarks and gluons. This and otherquestions are the central goals of the future Electron-Ion-Collider. Using noveltheoretical ideas I aim to contribute to the understanding of the spin structureof high energy QCD. The theoretical understanding of the real-time dynamics of anomalous and topological dynamics, as well as of the structure of high energy QCD is extremely challenging. In this proposal I will therefore outline how the out-of-equilibrium dynamics of anomalies, as well as the structure of high energy QCD, can be investigated using novel techniques such as real-time lattice simulations of fermions and gauge fields and string-theory-inspired methods such as the world-line method.

• DFG Programme: Research Fellowships
• International Connection: USA
• Hosts: Dr. Björn Schenke; Professor Dr. Raju Venugopalan