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M. Schweda

Publications and source records attributed to M. Schweda.

At least 19 recordsLinked to original sources
arXiv2005

Divergences in Non-Commutative Gauge Theories with the Slavnov Term

The divergence structure of non-commutative gauge field theories (NCGFT) with a Slavnov extension is examined at one-loop level with main focus on the gauge boson self-energy. Using an interpolating gauge we show that even with this extension the quadratic IR divergence of the gauge boson self-energy is independent from a covariant gauge fixing as well as from an axial gauge. The proposal of Slavnov is based on the fact that the photon propagator shows a new transversality condition with respect to the IR dangerous terms. This novel transversality is implemented with the help of a new dynamical multiplier field. However, one expects that in physical observables such contributions disappear. A further new feature is the existence of new UV divergences compatible with the gauge invariance (BRST symmetry). We then examine two explicit models with couplings to fermions and scalar fields.

hep-th↗
arXiv2005

Gauge (in)dependence and UV/IR mixing

The gauge independence in connection with the UV/IR-mixing is discussed with the help of the non-commutative U(1)-gauge field model proposed by A. A. Slavnov with two different gauges: the covariant gauge fixing defined via a gauge parameter αand the non-standard axial-gauge depending on a fixed gauge direction n^μ.

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arXiv2003

Space/time noncommutative field theories and causality

As argued previously, amplitudes of quantum field theories on noncommutative space and time cannot be computed using naive path integral Feynman rules. One of the proposals is to use the Gell-Mann--Low formula with time-ordering applied before performing the integrations. We point out that the previously given prescription should rather be regarded as an interaction point time-ordering. Causality is explicitly violated inside the region of interaction. It is nevertheless a consistent procedure, which seems to be related to the interaction picture of quantum mechanics. In this framework we compute the one-loop self-energy for a space/time noncommutative ϕ^4 theory. Although in all intermediate steps only three-momenta play a role, the final result is manifestly Lorentz covariant and agrees with the naive calculation. Deriving the Feynman rules for general graphs, we show, however, that such a picture holds for tadpole lines only.

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arXiv2003

The Energy-Momentum Tensor in Noncommutative Gauge Field Models

We discuss the different possibilities of constructing the various energy-momentum tensors for noncommutative gauge field models. We use Jackiw's method in order to get symmetric and gauge invariant stress tensors--at least for commutative gauge field theories. The noncommutative counterparts are analyzed with the same methods. The issues for the noncommutative cases are worked out.

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arXiv2003

Non-commutative U(1) Super-Yang-Mills Theory: Perturbative Self-Energy Corrections

The quantization of the non-commutative N=1, U(1) super-Yang-Mills action is performed in the superfield formalism. We calculate the one-loop corrections to the self-energy of the vector superfield. Although the power-counting theorem predicts quadratic ultraviolet and infrared divergences, there are actually only logarithmic UV and IR divergences, which is a crucial feature of non-commutative supersymmetric field theories.

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arXiv2002

IR-Singularities in Noncommutative Perturbative Dynamics?

We analyse the IR-singularities that appear in a noncommutative scalar quantum field theory on $\mathcal{E}_4$. We demonstrate with the help of the quadratic one-loop effective action and an appropriate field redefinition that no IR-singularities exist. No new degrees of freedom are needed to describe the UV/IR-mixing.

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arXiv2002

The role of the field redefinition in noncommutative Maxwell theory

We discuss $θ$-deformed Maxwell theory at first order in $θ$ with the help of the Seiberg-Witten (SW) map. With an appropriate field redefinition consistent with the SW-map we analyse the one-loop corrections of the vacuum polarization of photons. We show that the radiative corrections obtained in a previous work may be described by the Ward-identity of the BRST-shift symmetry corresponding to a field redefinition.

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arXiv2001

Symmetries of topological field theories in the BV-framework

Topological field theories of Schwarz-type generally admit symmetries whose algebra does not close off-shell, e.g. the basic symmetries of BF models or vector supersymmetry of the gauge-fixed action for Chern-Simons theory (this symmetry being at the origin of the perturbative finiteness of the theory). We present a detailed discussion of all these symmetries within the algebraic approach to the Batalin-Vilkovisky formalism. Moreover, we discuss the general algebraic construction of topological models of both Schwarz- and Witten-type.

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arXiv2001

Noncommutative spin-1/2 representations

In this letter we apply the methods of our previous paper hep-th/0108045 to noncommutative fermions. We show that the fermions form a spin-1/2 representation of the Lorentz algebra. The covariant splitting of the conformal transformations into a field-dependent part and a θ-part implies the Seiberg-Witten differential equations for the fermions.

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arXiv2001

Noncommutative Lorentz Symmetry and the Origin of the Seiberg-Witten Map

We show that the noncommutative Yang-Mills field forms an irreducible representation of the (undeformed) Lie algebra of rigid translations, rotations and dilatations. The noncommutative Yang-Mills action is invariant under combined conformal transformations of the Yang-Mills field and of the noncommutativity parameter θ. The Seiberg-Witten differential equation results from a covariant splitting of the combined conformal transformations and can be computed as the missing piece to complete a covariant conformal transformation to an invariance of the action.

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arXiv2001

Deformed QED via Seiberg-Witten Map

With the help of the Seiberg-Witten map for photons and fermions we define a theta-deformed QED at the classical level. Two possibilities of gauge-fixing are discussed. A possible non-Abelian extension for a pure theta-deformed Yang-Mills theory is also presented.

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arXiv2001

Perturbative Analysis of the Seiberg-Witten Map

We investigate the quantization of the theta-expanded noncommutative U(1) Yang-Mills action, obtained via the Seiberg-Witten map. As expected we find non-renormalizable terms. The one-loop propagator corrections are gauge independent, and lead us to a unique extention of the noncommutative classical action. We interpret our results as a requirement that also the trace in noncommutative field theory should be deformed.

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arXiv2000

The Superfield Formalism Applied to the Noncommutative Wess-Zumino Model

We introduce the notion of superoperators on noncommutative R^4 and re-investigate in the framework of superfields the noncommutative Wess-Zumino model as a quantum field theory. In a highly efficient manner we are able to confirm the result that this model is renormalizable to all orders.

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arXiv2000

Perturbative Chern-Simons Theory on Noncommutative R^3

A U(N) Chern-Simons theory on noncommutative $\mathbb{R}^{3}$ is constructed as a $\q$-deformed field theory. The model is characterized by two symmetries: the BRST-symmetry and the topological linear vector supersymmetry. It is shown that the theory is finite and $\q_{\m\n}$-independent at the one loop level and that the calculations respect the restriction of the topological supersymmetry. Thus the topological $\q$-deformed Chern-Simons theory is an example of a model which is non-singular in the limit $\q \to 0$.

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