ERC FUNDED PROJECTS

Four years ago, the LIGO/Virgo observation of a black-hole binary merger heralded the dawn of gravitational-wave astronomy. The promise of future observations calls for an invigorated effort to underpin the theoretical framework and supply the predictions needed for detecting future signals and exploiting them for astronomical and astrophysical studies. Ampl2Einstein will take ideas and techniques from recent years' dramatic advances in Quantum Scattering Amplitudes, creating new tools for taking their classical limits and using it for gravitational physics. The powerful `square root' relation between gravity and a generalization of electrodynamics known as Yang--Mills theory will play a key role in making this route simpler than direct classical calculation. We will transfer these ideas to classical General Relativity to compute new perturbative orders, spin-dependent observables, and the dependence on the internal structure of merging objects. We will exploit symmetries and structure we find in order to extrapolate to even higher orders in the gravitational theory. We will make such calculations vastly simpler, pushing the known frontier much further in perturbation theory and in complexity of observables. These advances will give rise to a new generation of gravitational-wave templates, dramatically extending the observing power of detectors. They will allow observers to see weaker signals and will be key to resolving long-standing puzzles about the internal structure of neutron stars. We will apply novel technologies developed for scattering amplitudes to bound-state calculations in both quantum and classical theory. Our research will also lead to a deeper understanding of the classical limit of quantum field theory, relevant to gravitational-wave observations and beyond. The transfer of ideas to the new domain of General Relativity will dramatically enhance our ability to reveal new physics encoded in the subtlest of gravitational-wave signals.

2 372 571 €

Start date: 2021-01-01, End date: 2025-12-31

I propose a program of research that may forever change the way that we understand and use quantum field theory to make predictions for experiment. This will be achieved through the advancement of new, constructive frameworks to determine and represent scattering amplitudes in perturbation theory in terms that depend only on observable quantities, make manifest (all) the symmetries of the theory, and which can be efficiently evaluated while minimally spoiling the underlying simplicity of predictions. My research has already led to the discovery and development of several approaches of this kind. This proposal describes the specific steps required to extend these ideas to more general theories and to higher orders of perturbation theory. Specifically, the plan of research I propose consists of three concrete goals: to fully characterize the discontinuities of loop amplitudes (`on-shell functions') for a broad class of theories; to develop powerful new representations of loop amplitude {\it integrands}, making manifest as much simplicity as possible; and to develop new techniques for loop amplitude {integration} that are compatible with and preserve the symmetries of observable quantities. Progress toward any one of these objectives would have important theoretical implications and valuable practical applications. In combination, this proposal has the potential to significantly advance the state of the art for both our theoretical understanding and our computational reach for making predictions for experiment. To achieve these goals, I will pursue a data-driven, `phenomenological' approach—involving the construction of new computational tools, developed in pursuit of concrete computational targets. For this work, my suitability and expertise is amply demonstrated by my research. I have not only played a key role in many of the most important theoretical developments in the past decade, but I have personally built the most powerful computational tools for their

1 499 695 €

Start date: 2018-02-01, End date: 2023-01-31

Today, much interest in several fields of physics is devoted to the study of small, open quantum systems, whose properties are profoundly affected by the environment; i.e., the continuum of decay channels. In nuclear physics, these problems were originally studied in the context of nuclear reactions but their importance has been reestablished with the advent of radioactive-beam physics and the resulting interest in exotic nuclei. In particular, strong theory initiatives in this area of research will be instrumental for the success of the experimental program at the Facility for Antiproton and Ion Research (FAIR) in Germany. In addition, many of the aspects of open quantum systems are also being explored in the rapidly evolving research on ultracold atomic gases, quantum dots, and other nanodevices. A first-principles description of open quantum systems presents a substantial theoretical and computational challenge. However, the current availability of enormous computing power has allowed theorists to make spectacular progress on problems that were previously thought intractable. The importance of computational methods to study quantum many-body systems is stressed in this proposal. Our approach is based on the ab initio no-core shell model (NCSM), which is a well-established theoretical framework aimed originally at an exact description of nuclear structure starting from realistic inter-nucleon forces. A successful completion of this project requires extensions of the NCSM mathematical framework and the development of highly advanced computer codes. The '++' in the project title indicates the interdisciplinary aspects of the present research proposal and the ambition to make a significant impact on connected fields of many-body physics.

1 304 800 €

Start date: 2009-12-01, End date: 2014-11-30

"This proposal addresses major questions in particle physics that are at the forefront of experimental and theoretical physics research today. The results offered would have far-reaching implications in other fields such as cosmology and could help answer some of the big questions such as why the universe contains so much more matter than antimatter. The research objectives of this proposal are to (i) make world-leading tests of CPT symmetry and (ii) discover the neutrino mass hierarchy and search for indications of leptonic CP violation. The NOvA long-baseline neutrino oscillation experiment will use a novel ""totally active scintillator design"" for the detector technology and will be exposed to the world's highest power neutrino beam. Building on the first direct observation of muon antineutrino disappearance (that was made by a group founded and led by the PI at the MINOS experiment), tests of CPT symmetry will be performed by looking for differences in the mass squared splittings and mixing angles between neutrinos and antineutrinos. The potential to discover the mass hierarchy is unique to NOvA on the timescale of this proposal due to the long 810 km baseline and the well measured beam of neutrinos and antineutrinos. This proposal addresses several key challenges in a long-baseline neutrino oscillation experiment with the following tasks: (i) development of a new approach to event energy reconstruction that is expected to have widespread applicability for future neutrino experiments; (ii) undertaking a comprehensive calibration project, exploiting a novel technique developed by the PI, that will be essential to achieving the physics goals; (iii) development of a sophisticated statistical analyses. The results promised in this proposal surpass the sensitivity to antineutrino oscillation parameters of current 1st generation experiments by at least an order of magnitude, offering wide scope for profound discoveries with implications across disciplines."

1 415 848 €

Start date: 2012-10-01, End date: 2018-09-30