The Phase Diagram for Wess-Zumino Models (2009)
Synatschke, Franziska, Gies, Holger, Wipf, Andreas
Dynamical supersymmetry breaking is an important issue for applications of supersymmetry in particle physics. The functional renormalization group equations allow for a nonperturbative approach that...
Phase Diagram and Fixed-Point Structure of two dimensional N=1 Wess-Zumino Models (2009)
Synatschke, Franziska, Gies, Holger, Wipf, Andreas
We study the phases and fixed-point structure of two-dimensional supersymmetric Wess-Zumino models with one supercharge. Our work is based on the functional renormalization group formulated in terms...
Effective Polyakov Loop Dynamics for Finite Temperature G(2) Gluodynamics (2009)
Wellegehausen, Bjoern H., Wipf, Andreas, Wozar, Christian
Based on the strong coupling expansion we obtain effective 3-dimensional models for the Polyakov loop in finite-temperature G_2 gluodynamics. The Svetitsky-Jaffe conjecture relates the resulting...
Supersymmetry breaking as a quantum phase transition (2009)
Gies, Holger, Synatschke, Franziska, Wipf, Andreas
We explore supersymmetry breaking in the light of a rich fixed-point structure of two-dimensional supersymmetric Wess-Zumino models with one supercharge using the functional renormalization group...
Confinement and the quark Fermi-surface in SU(2N) QCD-like theories (2009)
Langfeld, Kurt, Wellegehausen, Bjoern H., Wipf, Andreas
Yang-Mills theories with a gauge group SU(N_c\=3)and quark matter in the fundamental representation share many properties with the theory of strong interactions, QCD with N_c=3. We show that, for N_c...
Analytic results for the effective action (2009)
Blau, Steven K., Visser, Matt, Wipf, Andreas
Motivated by the seminal work of Schwinger, we obtain explicit closed form expressions for the one-loop effective action in a constant electromagnetic field. We discuss both massive and massless...
Zeta Functions and the Casimir Energy (2009)
Blau, Steven K., Visser, Matt, Wipf, Andreas
We use zeta function techniques to give a finite definition for the Casimir energy of an arbitrary ultrastatic spacetime with or without boundaries. We find that the Casimir energy is intimately...
Instanton constituents and fermionic zero modes in twisted CP(n) models (2009)
Brendel, Wieland, Bruckmann, Falk, Janssen, Lukas, Wipf, Andreas, Wozar, Christian
We construct twisted instanton solutions of CP(n) models. Generically a charge-k instanton splits into k(n+1) well-separated and almost static constituents carrying fractional topological charges and...
Flow Equation for Supersymmetric Quantum Mechanics (2008)
Synatschke, Franziska, Bergner, Georg, Gies, Holger, Wipf, Andreas
We study supersymmetric quantum mechanics with the functional RG formulated in terms of an exact and manifestly off-shell supersymmetric flow equation for the effective action. We solve the flow...
Numerical Investigation of the 2D N=2 Wess-Zumino Model (2008)
Wozar, Christian, Bergner, Georg, Kaestner, Tobias, Uhlmann, Sebastian, Wipf, Andreas
We study lattice formulations of the two-dimensional N=2 Wess-Zumino model with a cubic superpotential. Discretizations with and without lattice supersymmetries are compared. We observe that the...
Inverse Monte-Carlo and Demon Methods for Effective Polyakov Loop Models of SU(N)-YM (2008)
Wozar, Christian, Kaestner, Tobias, Wellegehausen, Bjoern H., Wipf, Andreas, Heinzl, Thomas
We study effective Polyakov loop models for SU(N) Yang-Mills theories at finite temperature. In particular effective models for SU(3) YM with an additional adjoint Polyakov loop potential are...
Two-Dimensional Wess-Zumino Models at Intermediate Couplings (2008)
Kaestner, Tobias, Bergner, Georg, Uhlmann, Sebastian, Wipf, Andreas, Wozar, Christian
We consider the two-dimensional N=(2,2) Wess-Zumino model with a cubic superpotential at weak and intermediate couplings. Refined algorithms allow for the extraction of reliable masses in a region...
Relation between chiral symmetry breaking and confinement in YM-theories (2008)
Synatschke, Franziska, Wipf, Andreas, Langfeld, Kurt
Spectral sums of the Dirac-Wilson operator and their relation to the Polyakov loop are thoroughly investigated. The approach by Gattringer is generalized to mode sums which reconstruct the Polyakov...
Supersymmetric lattice models in one and two dimensions (2007)
Kaestner, Tobias, Bergner, Georg, Uhlmann, Sebastian, Wipf, Andreas, Wozar, Christian
We study and simulate N=2 supersymmetric Wess-Zumino models in one and two dimensions. For any choice of the lattice derivative, the theories can be made manifestly supersymmetric by adding...
Z_3 Polyakov Loop Models and Inverse Monte-Carlo Methods (2007)
Wozar, Christian, Kaestner, Tobias, Uhlmann, Sebastian, Wipf, Andreas, Heinzl, Thomas
We study effective Polyakov loop models for SU(3) Yang-Mills theory at finite temperature. A comprehensive mean field analysis of the phase diagram is carried out and compared to the results obtained...
Low-dimensional Supersymmetric Lattice Models (2007)
Bergner, Georg, Kaestner, Tobias, Uhlmann, Sebastian, Wipf, Andreas
We study and simulate N=2 supersymmetric Wess-Zumino models in one and two dimensions. For any choice of the lattice derivative, the theories can be made manifestly supersymmetric by adding...
Wozar, Christian, Kaestner, Tobias, Wipf, Andreas, Heinzl, Thomas
This paper concludes our efforts in describing SU(3)-Yang-Mills theories at different couplings/temperatures in terms of effective Polyakov-loop models. The associated effective couplings are...
Spectral sums of the Dirac-Wilson Operator and their relation to the Polyakov loop (2007)
Synatschke, Franziska, Wipf, Andreas, Wozar, Christian
We investigate and compute spectral sums of the Wilson lattice Dirac operator for quenched SU(3) gauge theory. It is demonstrated that there exist sums which serve as order parameters for the...
Generalized Potts-Models and their Relevance for Gauge Theories (2007)
Andreas Wipf, Thomas Heinzl, Tobias Kaestner, Christian Wozar
We study the Polyakov loop dynamics originating from finite-temperature Yang-Mills theory. The effective actions contain center-symmetric terms involving powers of the Polyakov loop, each with its...
The integral form of APS boundary conditions in the Bag Model (2006)
Abrikosov Jr., Alexey A., Wipf, Andreas
We propose an integral form of Atiah-Patodi-Singer spectral boundary conditions (SBC) and find explicitly the integral projector onto SBC for the 3-dimensional spherical cavity. After discussion of a...
Generalized Potts-Models and their Relevance for Gauge Theories (2006)
Wipf, Andreas, Heinzl, Thomas, Kaestner, Tobias, Wozar, Christian
We study the Polyakov loop dynamics originating from finite-temperature Yang-Mills theory. The effective actions contain center-symmetric terms involving powers of the Polyakov loop, each with its...
Phase Structure of Z(3)-Polyakov-Loop Models (2006)
Wozar, Christian, Kaestner, Tobias, Wipf, Andreas, Heinzl, Thomas, Pozsgay, Balazs
We study effective lattice actions describing the Polyakov loop dynamics originating from finite-temperature Yang-Mills theory. Starting with a strong-coupling expansion the effective action is...
Effective Lattice Actions for Finite-Temperature Yang-Mills Theory (2005)
Heinzl, Thomas, Kaestner, Tobias, Wipf, Andreas
We determine effective lattice actions for the Polyakov loop using inverse Monte Carlo techniques.
Non-perturbative Methods in Supersymmetric Theories (2005)
The aim of these notes is to provide a short introduction to supersymmetric theories: supersymmetric quantum mechanics, Wess-Zumino models and supersymmetric gauge theories. A particular emphasis is...
Effective Actions for the SU(2) Confinement-Deconfinement Phase Transition (2005)
Heinzl, Thomas, Kaestner, Tobias, Wipf, Andreas
We compare different Polyakov loop actions yielding effective descriptions of finite-temperature SU(2) Yang-Mills theory on the lattice. The actions are motivated by a simultaneous strong-coupling...
Effective lattice theories for Polyakov loops (2003)
Dittmann, Leander, Heinzl, Thomas, Wipf, Andreas
We derive effective actions for SU(2) Polyakov loops using inverse Monte Carlo techniques. In a first approach, we determine the effective couplings by requiring that the effective ensemble...
Effective sigma models and lattice Ward identities (2002)
Dittmann, Leander, Heinzl, Thomas, Wipf, Andreas
We perform a lattice analysis of the Faddeev-Niemi effective action conjectured to describe the low-energy sector of SU(2) Yang-Mills theory. To this end we generate an ensemble of unit vector fields...
Classical Gauge Vacua as Knots (2001)
Van Baal, Pierre, Wipf, Andreas
The four dimensional O(3) non-linear sigma model introduced by Faddeev and Niemi, with a Skyrme-like higher order term to stabilise static knot solutions classified by the Hopf invariant, can be...
Black hole pair creation in de Sitter space: a complete one-loop analysis (2000)
Volkov, Mikhail S., Wipf, Andreas
We present an exact one-loop calculation of the tunneling process in Euclidean quantum gravity describing creation of black hole pairs in a de Sitter universe. Such processes are mediated by...
Quantum Fields near Black Holes (1998)
This review gives an introduction into problems, concepts and techniques when quantizing matter fields near black holes. The first part focusses on quantum fields in general curved space-times. The...
Finite Temperature Schwinger Model with Chirality Breaking Boundary Conditions (1996)
The $N_f$-flavour Schwinger Model on a finite space $0\leq x^1\leq L$ and subject to bag-type boundary-conditions at $x^1=0$ und $x^1=L$ is solved at finite temperature $T=1/\beta$. The boundary...
Functional Schroedinger Equation for Fermions in External Gauge Fields (1993)
We discuss the functional Schroedinger picture for fermions in external fields for both stationary and time-dependent problems. We give formal results for the ground state and the solution of the...