8,646 research outputs found
Perturbative analysis on infrared aspects of noncommutative QED on R^4
Here we examine the noncommutative counterpart of QED, which is called as
noncommutative QED. The theory is obtained by examining the consistent minimal
coupling to noncommutative U(1) gauge field. The *-product admits the coupling
of the matter with only three varieties of charges, i.e., 0, +1 and -1.
Ultraviolet divergence can be absorbed into the rescaling of the fields and the
parameters at least at one loop level. To examine the infrared aspect of the
theory the anomalous magnetic dipole moment is calculated. The dependence on
the direction of photon momentum reflects the Lorentz symmetry violation of the
system. The explicit calculation of the finite part of the photon vacuum
polarization shows the singularity ln({q C^TC q}) (C^{\mu\nu} is a
noncommutative parameter.) in the infrared side which also exists in
noncommutative Yang-Mills theory. It is associated with the ultraviolet
behavior of the theory. We also consider the extension to chiral gauge theory
in the present context, but the requirement of anomaly cancellation allows only
noncommutative QED.Comment: 10 pages, LaTEX2e, A part of results changed, reference adde
New physics for muon anomalous magnetic moment and its electroweak precision analysis
About 3 sigma deviation from the standard model prediction of muon anomalous
magnetic moment (muon g-2) has been reported. We consider new physics beyond
the standard model which has new Yukawa interactions with muon. We compute new
contributions to muon g-2 and corrections to electroweak observables, and show
the consistent region of parameter space. We find that in a simple model where
the chirality flip of muon occurs only in the external muon line in one-loop
muon g-2 diagrams, it is necessary to introduce the relatively large new Yukawa
coupling and the electroweak scale new particles. On the other hand, in a model
where the chirality flip can occur in the internal fermion line of one loop
muon g-2 diagrams, we can obtain favorable g-2 contributions without large
Yukawa coupling, and they are consistent with the precision electroweak
observables. Finally, we discuss effects of new particles for muon g-2 on the
Higgs boson decay h to 2 photons and direct productions of these particles at
the LHC experiment.Comment: 31 pages, 20 figure
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