Voja Radovanovic

Nonzero Z{yields}{gamma}{gamma} decays in the renormalizable gauge sector of the noncommutative standard model

In this work we propose the Z -> gamma gamma decay as a process strictly forbidden in the standard model, suitable for the search of noncommutativity of coordinates at very short distances. We computed the Z -> gamma gamma partial width in the framework of the recently proposed one-loop renormalizable gauge sector of the noncommutative standard model. New experimental possibilities at LHC are analyzed and a firm bound to the scale of noncommutativity parameter is set around 1 TeV.

The one-loop renormalization of the gauge sector in the θ-expanded noncommutative standard model

In this paper we construct a version of the standard model gauge sector on noncommutative space-time which is one-loop renormalizable to first order in the expansion in the noncommutativity parameter ?. The one-loop renormalizability is obtained by the Seiberg-Witten redefinition of the noncommutative gauge potential for the model containing the usual six representations of matter fields of the first generation.

Renormalizability of noncommutative SU(N) gauge theory

We analyze the renormalizability properties of pure gauge noncommutative SU(N) theory in the θ-expanded approach. We find that the theory is one-loop renormalizable to first order in θ.

Non-renormalizability of noncommutative SU(2) gauge theory with fermions

We analyze the divergent part of the one-loop effective action for the noncommutative SU(2) gauge theory coupled to the fermions in the fundamental representation. We show that the divergencies in the 2-point and the 3-point functions in the

Chiral fermions in noncommutative electrodynamics: Renormalizability and dispersion

\theta

Non-commutative SU(N) gauge theories and asymptotic freedom

-linear order can be renormalized, while the divergence in the 4-point fermionic function cannot.

The one-loop effective action for quantum electrodynamics on noncommutative space

We analyze quantization of noncommutative chiral electrodynamics in the enveloping algebra formalism in linear order in noncommutativity parameter {theta}. Calculations show that divergences exist and cannot be removed by ordinary renormalization; however, they can be removed by the Seiberg-Witten redefinition of fields. Performing redefinitions explicitly, we obtain renormalizable Lagrangian and discuss the influence of noncommutativity on field propagation. Noncommutativity affects the propagation of chiral fermions only: half of the fermionic modes become massive and birefringent.

Field theory on nonanticommutative superspace

In this paper we analyze the one-loop renormalization of the θ-expanded SU(N) Yang-Mills theory. We show that the freedom parameter a, key to renormalization, originates from higher order non-commutative gauge interaction, represented by a higher derivative term b h θ �ν b F�ν ⋆ b Fρσ ⋆ b F ρσ . The renormalization condition fixes the allowed values of the parameter a to one of the two solutions: a = 1 or a = 3, i.e. to b = 0 or to b = 1/2, respectively. When the higher order interaction is switched on, (a = 3), pure non-commutative SU(N) gauge theory at first order in θ-expansion becomes one-loop renormalizable for various representations of the gauge group. We also show that, in the case a = 3 and the adjoint representation of the gauge fields, the non-commutative deformation parameter h has to be renormalized and it is asymptotically free.

Absence of the4ψdivergence in noncommutative chiral models

In this paper we calculate the divergent part of the one loop effective action for QED on noncommutative space using the background field method. The effective action is obtained up to the second order in the noncommutativity parameter θ and in the classical fields.

Two-loop Back-reaction in 2D Dilaton Gravity

We discuss a deformation of the Hopf algebra of supersymmetry (SUSY) transformations based on the special choice of twist. As usual, algebra itself remains unchanged, but the comultiplication changes. This leads to the deformed Leibniz rule for SUSY transformations. Superfields are elements of the algebra of functions of the usual supercoordinates. Elements of this algebra are multiplied by using the -product which is noncommutative, hermitian and finite when expanded in power series of the deformation parameter. Chiral fields are no longer a subalgebra of the algebra of superfields. One possible deformation of the Wess-Zumino action is proposed and analyzed in detail. Differently from most of the literature concerning this subject, we work in Minkowski space-time.