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A. Thimm

Publications and source records attributed to A. Thimm.

7 recordsLinked to original sources
arXiv2000

On the eta-invariant in the 4D chiral U(1) theory

In contrast to its counterpart in a vector theory, the effective action of a chiral gauge theory may have a non-vanishing imaginary part. It consists of the so-called Chern-Simons form, which encodes the anomaly and a gauge invariant piece related to the eta-invariant of some extended Dirac operator. We investigate the imaginary part of the effective action in the 4D chiral U(1) theory within the continuum fermion approach. Perturbative analysis indicates in general a non-vanishing imaginary part of the effective action. However, after anomaly cancellation we find only a small value of the imaginary part for the investigated configurations.

hep-lat↗
arXiv1999

Lattice chiral fermions in the background of non-trivial topology

We address the problem of numerical simulations in the background non-trivial topology in the chiral Schwinger model. An effective fermionic action is derived which is in accord with established analytical results, and which satisfies the anomaly equation. We describe a numerical evaluation of baryon number violating amplitudes, specifically the 't Hooft vertex.

hep-lat↗
arXiv1998

Chiral Fermions on the Lattice

A recently proposed method for regularizing chiral gauge theories non-perturbatively is discussed in detail. The result is an effective action which can be computed from the lattice gauge field, and which is suited for numerical simulations.

hep-lat↗
arXiv1998

Lattice Chiral Schwinger Model: Selected Results

We discuss a method for regularizing chiral gauge theories. The idea is to formulate the gauge fields on the lattice, while the fermion determinant is regularized and computed in the continuum. A simple effective action emerges which lends itself to numerical simulations.

hep-lat↗
arXiv1997

Lattice Chiral Schwinger Model in the Continuum Formulation

We pursue further an approach to lattice chiral fermions in which the fermions are treated in the continuum. To render the effective action gauge invariant, counterterms have to be introduced. We determine the counterterms for smooth gauge fields, both analytically and numerically. The final result is that the imaginary part of the effective action can be computed analytically from the lattice gauge field, while the real part is given by one half of the action of the corresponding vector model.

hep-lat↗