Gauge theories in local causal perturbation theory

In this thesis quantum gauge theories are considered in the framework of local, causal perturbation theory. Gauge invariance is described in terms of the BRS formalism. Local interacting field operators are constructed perturbatively and field equations are established. A nilpotent BRS transformation is defined on the local algebra of fields. It allows the definition of the algebra of local observables as an operator cohomology. This algebra of local observables can be represented in a Hilbert space. The interacting field operators are defined in terms of time ordered products of free field operators. For the results above to hold the time ordered products must satisfy certain normalization conditions. To formulate these conditions also for field operators that contain a spacetime derivative a suitable mathematical description of time ordered products is developed. Among the normalization conditions are Ward identities for the ghost current and the BRS current. The latter are generalizations of a normalization condition that is postulated by D"utsch, Hurth, Krahe and Scharf for Yang-Mills theory. It is not yet proven that this condition has a solution in every order. All other normalization conditions can be accomplished simultaneously. A principle for the correspondence between interacting quantum fields and interacting classical fields is established. Quantum electrodynamics and Yang-Mills theory are examined and the results are compared with the literature.Comment: PhD thesis, 84 page

A first principle computation of the thermodynamics of glasses

We propose a first principle computation of the equilibrium thermodynamics of simple fragile glasses starting from the two body interatomic potential. A replica formulation translates this problem into that of a gas of interacting molecules, each molecule being built of m atoms, and having a gyration radius (related to the cage size) which vanishes at zero temperature. We use a small cage expansion, valid at low temperatures, which allows to compute the cage size, the specific heat (which follows the Dulong and Petit law), and the configurational entropy.Comment: Latex, 40 pages, 9 figures, corrected misprints, improved presentatio

Theory of the n=2 levels in muonic deuterium

The present knowledge of Lamb shift, fine- and hyperfine structure of the $\mathrm{2S}$ and $\mathrm{2P}$ states in muonic deuterium is reviewed in anticipation of the results of a first measurement of several $\mathrm{2S-2P}$ transition frequencies in muonic deuterium ($\mu\mathrm{d}$). A term-by-term comparison of all available sources reveals reliable values and uncertainties of the QED and nuclear structure-dependent contributions to the Lamb shift, which are essential for a determination of the deuteron rms charge radius from $\mu\mathrm{d}$. Apparent discrepancies between different sources are resolved, in particular for the difficult two-photon exchange contributions. Problematic single-sourced terms are identified which require independent recalculation.Comment: 26 pages, add missing feynman diagrams (Fig. 3), renumber items (Tab. IV), correct a sum (column 5, Tab. IV

The Hierarchical Random Energy Model

We introduce a Random Energy Model on a hierarchical lattice where the interaction strength between variables is a decreasing function of their mutual hierarchical distance, making it a non-mean field model. Through small coupling series expansion and a direct numerical solution of the model, we provide evidence for a spin glass condensation transition similar to the one occuring in the usual mean field Random Energy Model. At variance with mean field, the high temperature branch of the free-energy is non-analytic at the transition point

AiLingo – A Design Science Approach to Advancing Non-Expert Adults’ AI Literacy

Non-experts struggle in human-AI collaboration due to AI’s differences from more traditional technologies, such as inscrutability. Meanwhile, information systems research on AI education primarily focuses on students in formal learning settings and neglects non-expert adults. Applying a design science research approach, we develop a learning application (“AiLingo”) as an informal learning experience to advance non-expert adults’ AI literacy. Based on self-determination theory, we deduct design principles and features tailored to non-expert adults. Through experimental evaluation (n = 101), we find that a learning experience with our design features present (vs. absent) leads to greater AI literacy advancement. Additionally, we find downstream effects of AI literacy, as it increases AI usage continuance intention and leads to a more positive attitude toward AI. Our study contributes to AI literacy and educational literature with a perspective on non-expert adults, novel design knowledge for AI education, and the discovery of crucial AI literacy consequences

Detecting the Upturn of the Solar 8^8B Neutrino Spectrum with LENA

LENA (Low Energy Neutrino Astronomy) has been proposed as a next generation 50 kt liquid scintillator detector. The large target mass allows a high precision measurement of the solar $^8$B neutrino spectrum, with an unprecedented energy threshold of 2 MeV. Hence, it can probe the MSW-LMA prediction for the electron neutrino survival probability in the transition region between vacuum and matter-dominated neutrino oscillations. Based on Monte Carlo simulations of the solar neutrino and the corresponding background spectra, it was found that the predicted upturn of the solar $^8$B neutrino spectrum can be detected with 5 sigma significance after 5 y

Phononic filter effect of rattling phonons in the thermoelectric clathrate Ba8_8Ge40+x_{40+x}Ni6−x_{6-x}

One of the key requirements for good thermoelectric materials is a low lattice thermal conductivity. Here we present a combined neutron scattering and theoretical investigation of the lattice dynamics in the type I clathrate system Ba-Ge-Ni, which fulfills this requirement. We observe a strong hybridization between phonons of the Ba guest atoms and acoustic phonons of the Ge-Ni host structure over a wide region of the Brillouin zone which is in contrast with the frequently adopted picture of isolated Ba atoms in Ge-Ni host cages. It occurs without a strong decrease of the acoustic phonon lifetime which contradicts the usual assumption of strong anharmonic phonon--phonon scattering processes. Within the framework of ab-intio density functional theory calculations we interpret these hybridizations as a series of an ti-crossings which act as a low pass filter, preventing the propagation of acoustic phonons. To highlight the effect of such a phononic low pass filter on the thermal transport, we compute the contribution of acoustic phonons to the thermal conductivity of Ba$_8$Ge$_{40}$Ni$_{6}$ and compare it to those of pure Ge and a Ge$_{46}$ empty-cage model system.Comment: 10 pages, 10 figure

How to compute the thermodynamics of a glass using a cloned liquid

The recently proposed strategy for studying the equilibrium thermodynamics of the glass phase using a molecular liquid is reviewed and tested in details on the solvable case of the $p$-spin model. We derive the general phase diagram, and confirm the validity of this procedure. We point out the efficacy of a system of two weakly coupled copies in order to identify the glass transition, and the necessity to study a system with $m<1$ copies ('clones') of the original problem in order to derive the thermodynamic properties of the glass phase.Comment: Latex, 17 pages, 6 figure