We discuss path integral derivations of topologically twisted partition functions of 5d SU(2) supersymmetric Yang-Mills theory on M4 x S1, where M4 is a smooth closed four-manifold. Mathematically, they can be identified with the K-theoretic version of the Donaldson invariants. In particular, we provide two different path integral derivations of their wall-crossing formula for b_2^+(M4)=1, first in the so-called U-plane integral approach, and in the perspective of instanton counting. We briefly discuss the generalization to b_2^+(M4)>1.

https://www.uni-kl.de/trr173/events/distinguished-lecture-series/summer-term-2022

We investigate the interaction of two paradigmatic ways of being out of equilibrium, aging and driving, in simple models of glassy dynamics. We specifically consider the Bouchaud model, where a system jumps between the numerous minima of a rough energy landscape in configuration space. As the temperature decreases, the system undergoes a dynamical phase transition, at which the relaxation time diverges. With an additional field, we then drive the system by biasing it's dynamics towards higher/lower jumping activity. We investigate the spectrum of the (biased) master operator in that framework, using a population dynamics algorithm based on cavity theory that allows us to deduce statements about the thermodynamic limit. Combining this with extensive diagonalization we identify novel regimes in the bias-temperature phase diagram that are distinguished by the occurrence of different kinds of eigenvector localization and are linked to the existence of a spectral gap. We also present methodological advances in the form of novel strategies for operating the population dynamics algorithm.

Die netto CO2-Emissionen sollen in Deutschland bis 2045 auf Null gesenkt werden. Andere Ländern haben sich zum Schutz des Klimas auf ähnliche Ziele verpflichtet. Der Mobilitätssektor trägt in Deutschland mit rund 20% zu den Gesamtemissionen bei und hat anders als die meisten anderen Sektoren seit 1990 keine signifikanten Reduktionen zu verzeichnen. Neben Anstrengungen das Verkehrsaufkommen z.B. durch Verlagerung vom Auto auf die Schiene, den ÖPNV oder das Fahrrad zu verringern, sind elektrische Antriebskonzepte ein technisch realistischer Weg, der inzwischen auch mit Nachdruck weltweit in der Automobilindustrie verfolgt wird. In PKW setzt sich aktuell weltweit das Konzept des batterieelektrischen Fahrzeugs durch. Entsprechend ist die Frage, wie der Stand der Batterietechnik ist, welche Materialsysteme aktuell und in absehbarer Zeit zum Einsatz kommen, wie es um die Sicherheit der Batterien und wie es um die Rohstoffverfügbarkeiten bestellt ist. Gleichzeitig steigt der Speicherbedarf auch im Stromsystem, um die stark fluktuierende Stromerzeugung aus Windkraft- und Photovoltaikanlagen zu vergleichmäßigen. Auch hier werden in großem Umfang Batteriespeicher zum Einsatz kommen, an die aber andere Anforderungen als im Mobilitätsbereich gestellt werden. Diskutiert werden auch die Aussichten von Batterietechnologien, die heute noch nicht in großem Umfang kommerziell eingesetzt werden und die Rolle von Wasserstoff und seinen Derivaten im Mobilitätsbereich.

The estimation of $\alpha$ at the electroweak scale is an important parameter required for electroweak precision tests. It is computed through a combination of $\e^+e^-\rightarrow\mathrm{hadrons}$ data plus perturbative QCD contributions. The combination of data and pQCD can be optimized to reduce the error on the prediction of $\alpha(M_Z)$. Here, I will study how different groups choose the theory/data splitting and compare the type of errors associated with each framework. Later, I will discuss the relation of the running of $\alpha$ with the one of the weak mixing angle. Finally light new physics which might affect the measurement of the weak mixing angle at low energies will be discussed.

The combined result of a number of experiments demonstrated that neutrinos have mass and oscillate. However fundamental questions about neutrinos remain: Is the neutrino its own antiparticle? What is the absolute scale of neutrino masses? How are the three neutrino mass states ordered? Is the CP symmetry violated in the neutrino sector? Are there sterile neutrino species? Current and future neutrino experiments are designed with state-of-the-art technology to provide answers to these questions. In this colloquium, the status of two of these experiments will be presented. On one hand, the Deep Underground Neutrino Experiment (DUNE) is a next generation experiment for long-baseline neutrino oscillation studies, neutrino astrophysics and beyond the standard model searches. DUNE will consist of a beam of neutrinos located at Fermilab (US), a near detector, and a far detector placed at Sanford Underground Research Facility 1,300 km away. The far detector will have a total mass of 70 kton of liquid argon and as a previous step the ProtoDUNE program is on-going at the CERN Neutrino Platform. On the other hand, the MAJORANA DEMONSTRATOR operated an array of germanium detectors searching for neutrinoless double-beta decay (0𝜈𝛽𝛽). The excellent performance of the detectors provided new exclusion limits on the searches for neutrinoless double-beta decay and other rare-events, such as dark matter and axions.
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I will discuss two experiments recently completed at UC Berkeley. In the first, we couple two ions via image charged induced in a 0.6 mm long wire to each other. While the efforts were aimed at establishing the much needed interface between individual quantum processors, the coupling can be used to cool, control and detect particles not accessible laser control and are thus relevant for precision metrology as recently shown by the BASE collaboration for cooling (anti)protons. In the second set of experiments, I will discuss a test of a nonlinear extension to quantum mechanics. Already in the early 80's, S. Weinberg and others were wondering whether the laws of nature at the quantum scale are nonlinear (Ann.Phys. (N.Y.), 194, 336-386 (1989)). Interest dropped rapidly when it was shown that those extensions violate causality. However, recently Kaplan and Rajendran (arXiv:2106.10576 [hep-th]) managed to add nonlinear and state-dependent terms without violating causality. Interestingly this extension rendered the existing experimental tests ineffective. I will discuss why a quantum mechanical object tied to a macroscopic object (such as an ion trap) provides a more stringent test to Rajendran and Kaplan's hypothesis and present experimental bounds ruling it out at the 1E-11 level.

Evaporating dispersion drops from superamphiphobic surfaces opens a way to fabricate supraparticles (SPs) with complex structures. The structure formation can be controlled by tailoring the interaction forces between particles and process conditions. In this study, the structure of the SPs was investigated by tuning the shape of the primary building blocks and by the addition of surfactant sodium dodecyl sulfate (SDS).