2,704 research outputs found
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
and states in muonic deuterium is reviewed in
anticipation of the results of a first measurement of several
transition frequencies in muonic deuterium (). 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
. 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 B 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 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 B neutrino
spectrum can be detected with 5 sigma significance after 5 y
Phononic filter effect of rattling phonons in the thermoelectric clathrate BaGeNi
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 BaGeNi and compare it to those of pure
Ge and a Ge 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 -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 copies ('clones') of the
original problem in order to derive the thermodynamic properties of the glass
phase.Comment: Latex, 17 pages, 6 figure
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