From dark matter and dark energy to neutrino oscillations and the lack of antimatter in the universe, there is growing evidence that the Standard Model is incomplete. Tests of Quantum Electrodynamics (QED) with few-electron systems offer a promising avenue for looking for new physics, as QED is the best understood quantum field theory and extremely precise predictions can be obtained for few-electron systems. Unfortunately, despite decades of effort, QED is poorly tested in the regime of strong coulomb fields, precisely the region where new exotic physics may be most visible. I will present a new paradigm for probing higher-order QED effects using spectroscopy of Rydberg states in exotic atoms, where orders of magnitude stronger field strengths can be achieved while nuclear uncertainties may be neglected. Such tests are now possible due to the advent of quantum sensing microcalorimeter x-ray detectors and new facilities providing low-energy intense beams of exotic particles for precision physics. First measurements have been successfully conducted at J-PARC with muonic atoms, but antiprotonic atoms offer the highest sensitivity to strong-field QED. I will present an overview of the PAX project, a new experiment for antiprotonic atom x-ray spectroscopy with a large-area transition edge sensor (TES) x-ray detector and low-energy cyclotron trap at ELENA. Finally, the experimental paradigm can also be reversed such to study low-lying states and access nuclear properties, such as those pursued in the QUARTET collaboration at Paul Scherrer Institute to improve the charge radii of light nuclei. I will present first results from QUARTET, and discuss synergies between atomic and nuclear physics accessible with these experiments.

This talk will present the detailed procedure of computing three-loop four-point Feynman integrals with one massive leg and the applications to three-point form factors and Higgs plus jet amplitudes. In the first part, I will discuss technical details of computing three-loop four-point Feynman integrals using differential equation methods. In the second part, I will discuss about the analytic properties of the form factors and recent updates on the form factors and Higgs plus jet amplitude.

The field of ultra-cold chemistry of ions and atoms has been launching the fundamental quest for investigating its quantum regime for decades. A simplifying summary of the quest might be: How do interactions and chemical reactions proceed at extremely low temperatures? The classical picture predicts that all dynamics comes to a standstill as zero velocity is approached. However, deviations are expected since the classical model ceases to be appropriate at microscopic scales and at low temperatures, where particle-wave dualism of matter get’s important. In this regime, quantum effects dominate and reactions are predicted to obey fundamentally different rules. Examples are: (i) collisions of atoms, necessary for a reaction, cannot be described as a billiard-like impact between hard spheres anymore, but rather as interfering waves, interacting at long range, which can coherently amplify or even decoherently annihilate each other. (ii) energy barriers can exceed the available kinetic energy, but nevertheless be efficiently passed via quantum tunnelling, ruling the dynamics. Experimentally, we immerse a single barium (Ba+) ion in a bath of fermionic lithium (Li) atoms. We span temperatures from far above room temperature down deep into the s-wave regime of nano-Kelvin. We report our results on exploiting the collision energy dependence of magnetically tunable atom-ion scattering (Feshbach) resonances and explain how to assign their partial-wave-classification experimentally. In the first half, we will give a basic tutorial on quantum scattering of atom-ion ensembles and distill the substantial differences to atom-atom dynamics. We aim to discuss how to gain control and state-sensitive detection on the level of individual quanta within the merged ion-atom system and to study and establish optically trapping of ions and atoms in general - for example to reveal the quantum dynamics of ion-atom and ion-molecule reactions in absence of any detrimental radio-frequency fields.