Magnetic resonance imaging is an inherently non-invasive technique with biological applications from the cellular to human size-scales. A major technological push has been towards stronger magnetic fields, which can be >20 Tesla for preclinical studies and >10 Tesla for humans, since these increase the signal strength and ultimate imaging resolution. Such systems, however, require advances in hardware design, acquisition sequences and image processing algorithms to achieve optimal performance. The first part of this talk will concentrate on technical challenges and practical approaches for human scanning at 7 Tesla and above. The challenges include B_1 and B_0 inhomogeneities, increased specific absorption rate, and high sensitivity to movement. Neurological and neuroscience applications discussed include ocular and neurological tumours, epilepsy, neuromuscular diseases, glymphatic clearance and mechanistic studies of lithium for bipolar disorders. The second part will discuss the opposite end of the MRI spectrum, ultra-low field systems at ~50 mT which have been designed to address the challenges of global healthcare accessibility. The challenges here are diametrically opposite to those at high field, and topics of system design, characterization and in vivo applications will be highlighted.

The CP violation observed in the hadronic decays of charmed mesons remains a puzzling open question for theorists. Calculations relying on the assumption of inelastic final-state interactions occurring between the pairs of pions and kaons fall short of the experimental value. It has been pointed out that a third channel of four pions can leave imprints on the CP asymmetries of the two-body decays. At the same time, plenty of data are available for rare decays such as \(D^0\to\pi^+\pi^-\ell^+\ell^-\), which provide a promising environment for the search for new physics. With this motivation, we study the cascade topology \(D^0\to a_1(1260)^+(\to \rho(770)^0\pi^+)\,\pi^-\), which has been measured to contribute significantly to the \(4\pi\) decays of the same meson, and estimate its effect on the branching ratio of the rare decays. I will also comment on the possibility of this topology contributing to the decay amplitude of \(D^0\to\pi^+\pi^-\) and by extension to the related CP asymmetry.

Thanks to their extremely weak interaction with matter and neutral electric charge, neutrinos travel vast cosmic distances without deflection, providing a unique and complementary approach to investigating the most energetic events in the Universe. Neutrino telescopes are designed to detect Cherenkov light inferred by neutrino interactions. After more than fifteen years of data collection, the pioneering ANTARES detector has been successfully dismantled, making way for its next-generation successor, KM3NeT, deployed at two sites in the Mediterranean Sea. Near the former ANTARES location, off the coast of Toulon (France), KM3NeT/ORCA is dedicated to studying the intrinsic properties of atmospheric neutrinos through their oscillations within the Earth. Further southeast, off the coast of Sicily, KM3NeT/ARCA is monitoring the high-energy sky in search of cosmic neutrinos. In this presentation, I will highlight the latest insights in neutrino (astro)physics emerging from the depths of the Mediterranean. Particular attention will be given to the recent detection of an ultra-high-energy neutrino event, designated KM3-230213A, by KM3NeT/ARCA. The observed particle is a muon with an estimated energy of 120+110−60 PeV. Its exceptionally high energy and nearly horizontal trajectory suggest that its parent neutrino originated from a cosmic accelerator or could potentially be the first detected cosmogenic neutrino—produced when ultra-high-energy cosmic rays interact with background photons in the Universe. This groundbreaking observation underscores the remarkable capabilities of deep-sea neutrino telescopes in unveiling new astrophysical phenomena. To also view graphic content, follow the link: https://www.thep.physik.uni-mainz.de/files/2025/04/Title_Abstract_Mainz_AK_16.04.2025.pdf

We aim to advance antimatter research through tabletop experiments that operate independently of accelerator infrastructure, allowing for much lower noise levels and freedom from beamtime schedules. Our approach involves Dual RadioFrequency Traps (DRFTs) to confine the constituents of antihydrogen: positrons and antiprotons. Due to the different charge-to-mass ratios, each species primarily couples to a separate RF field. Unlike other traps, DRFTs naturally allow two species, even those of opposite charge, to be brought close together so that high production rates of antihydrogen can be achieved. Additionally, their open geometry is advantageous for laser spectroscopy. In our pioneering study, we develop a DRFT for co-trapping electrons and calcium ions which act as stand-ins for positrons and antiprotons. We demonstrate seperate storage times of up to a second and are developing an improved DRFT to extend this. In parallel, we are developing a low-energy positron source which will allow us to study bound positron-atom systems while other groups work on developing tools to transport antiprotons for future studies on antihydrogen.