GRK 2575:  Rethinking Quantum Field Theory

• Subject Area: Particles, Nuclei and Fields
• Term: since 2020
• Website: Homepage
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 417533893

Quantum field theory (QFT) plays a fundamental role in theoretical physics. It provides the unification of quantum mechanics and special relativity and as such represents a major intellectual achievement of the past century in which much of modern theoretical physics culminates. First developed for quantum electrodynamics, then extended to the Standard Model, it may even be applied to perturbative treatments of Einstein’s gravity and beyond. A core principle of QFT is renormalization, giving divergencies encountered in perturbative computations a physical resolution and leading to the very important concept of effective field theory. The discretized variant of QFT, lattice field theory, enables us to mathematically define a QFT independent of the perturbative expansions and to also study its strongly coupled regime, employing numerical computations of the path integral. The fruitful interplay of quantum field theory with gravity led to many innovations in the field: The AdS/CFT duality yielding a strong coupled formulation of conformal gauge theories via string theory in anti-de-Sitter backgrounds, the double copy entangling Yang-Mills theory and gravity or the use of QFT techniques to perturbatively compute classical gravitational wave observables at high-precision. Finally, symmetries, being of space-time or internal nature, lie at the heart of our understanding of Nature at a fundamental level. Closely tied with QFT, they lead to an enormous reduction of the possible complexity of the theories that are currently being explored. In recent years, important innovations occurred, leading the community to seriously rethink core concepts within QFT. These innovations show that our traditional point of view on QFT is ripe for a deep rethinking. The outcome is a transformation of the foundations of the field and its technologies coupled with a rapid innovation in its applications: in phenomenology and gravitational wave science - directly linking to observations. Our RTG has made important contributions to this innovative research area in the first funding period. Our team is internationally unique in its broadness encompassing the main QFT research areas of scattering amplitudes, phenomenology, lattice field theory, the AdS/CFT correspondence, analytical gravitational wave physics and mathematical aspects of QFT in close vicinity and with international visibility. We have designed a timely qualification program for a new generation of quantum field theorists which will train them in these modern aspects of QFT. This broad education will lay a solid foundation for a successful scientific career in theoretical physics. The key elements are (i) introductory and advanced courses on QFT, (ii) an annual retreat with external lecturers and seminars, (iii) a monthly QFT colloquium, (iv) an internship in neighboring research groups, (v) self-organized student seminars, and (vi) professional soft skills training.

• DFG Programme: Research Training Groups
• Applicant Institution: Humboldt-Universität zu Berlin
• Participating Institution: Deutsches Elektronen-Synchrotron (DESY); Max-Planck-Institut für Gravitationsphysik; (Albert-Einstein-Institut)
• Spokesperson: Professor Dr. Jan Plefka
• Participating Researchers: Professor Dr. Gaëtan Borot; Professorin Dr. Alessandra Buonanno; Professorin Dr. Valentina Forini; Dr. Jeremy Green; Professor Dr. Christophe Grojean; Professor Dr. Olaf Hohm; Dr. Emanuel Malek; Dr. Peter Marquard; Professor Dr. Agostino Patella; Professor Dr. Matthias Staudacher; Dr. Jan Steinhoff