7,930 research outputs found
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 \theta-part implies the
Seiberg-Witten differential equations for the fermions.Comment: 7 pages, LaTe
IR-Singularities in Noncommutative Perturbative Dynamics?
We analyse the IR-singularities that appear in a noncommutative scalar
quantum field theory on . 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.Comment: 6 pages, amsLaTe
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 \theta. 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.Comment: 20 pages, LaTeX. v2: Streamlined proofs and extended discussion of
Lorentz transformation
On the Effective Action of Noncommutative Yang-Mills Theory
We compute here the Yang-Mills effective action on Moyal space by integrating
over the scalar fields in a noncommutative scalar field theory with harmonic
term, minimally coupled to an external gauge potential. We also explain the
special regularisation scheme chosen here and give some links to the Schwinger
parametric representation. Finally, we discuss the results obtained: a
noncommutative possibly renormalisable Yang-Mills theory.Comment: 19 pages, 6 figures. At the occasion of the "International Conference
on Noncommutative Geometry and Physics", April 2007, Orsay (France). To
appear in J. Phys. Conf. Se
Topological Graph Polynomials in Colored Group Field Theory
In this paper we analyze the open Feynman graphs of the Colored Group Field
Theory introduced in [arXiv:0907.2582]. We define the boundary graph
\cG_{\partial} of an open graph \cG and prove it is a cellular complex.
Using this structure we generalize the topological (Bollobas-Riordan) Tutte
polynomials associated to (ribbon) graphs to topological polynomials adapted to
Colored Group Field Theory graphs in arbitrary dimension
Genetic analysis of epidermal growth factor action: assignment of human epidermal growth factor receptor gene to chromosome 7.
Non-renormalizability of noncommutative SU(2) gauge theory
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 -linear order can be renormalized, while the
divergence in the 4-point fermionic function cannot.Comment: 15 pages, results presented at ESI 2d dilaton gravity worksho
Optical exciton Aharonov-Bohm effect, persistent current, and magnetization in semiconductor nanorings of type I and II
The optical exciton Aharonov-Bohm effect, i. e. an oscillatory component in
the energy of optically active (bright) states, is investigated in nanorings.
It is shown that a small effective electron mass, strong confinement of the
electron, and high barrier for the hole, achieved e. g. by an InAs nanoring
embedded in an AlGaSb quantum well, are favorable for observing the optical
exciton Aharonov-Bohm effect. The second derivative of the exciton energy with
respect to the magnetic field is utilized to extract Aharonov-Bohm oscillations
even for the lowest bright state unambiguously. A connection between the
theories for infinitesimal narrow and finite width rings is established.
Furthermore, the magnetization is compared to the persistent current, which
oscillates periodically with the magnetic field and confirms thus the
non-trivial (connected) topology of the wave function in the nanoring.Comment: 12 pages, 11 figure
One-loop effects in a self-dual planar noncommutative theory
We study the UV properties, and derive the explicit form of the one-loop
effective action, for a noncommutative complex scalar field theory in 2+1
dimensions with a Grosse-Wulkenhaar term, at the self-dual point. We also
consider quantum effects around non-trivial minima of the classical action
which appear when the potential allows for the spontaneous breaking of the U(1)
symmetry. For those solutions, we show that the one-loop correction to the
vacuum energy is a function of a special combination of the amplitude of the
classical solution and the coupling constant.Comment: Version to appear in JHE
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