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

Tenth-order lepton g-2: Contribution of some fourth-order radiative corrections to the sixth-order g-2 containing light-by-light-scattering subdiagrams

This paper reports the tenth-order QED contribution to lepton g-2 from diagrams of three gauge-invariant sets VI(d), VI(g), and VI(h), which are obtained by including various fourth-order radiative corrections to the sixth-order g-2 containing light-by-light-scattering subdiagrams. In the case of electron g-2, they consist of 492, 480, and 630 vertex Feynman diagrams, respectively. The results of numerical integration, including mass-dependent terms containing muon loops, are 1.8418(95) (alpha/pi)^5 for the Set VI(d), -1.5918(65) (alpha/pi)^5 for the Set VI(g), and 0.1797(40) (alpha/pi)^5 for the Set VI(h), respectively. We also report the contributions to the muon g-2, which derive from diagrams containing an electron, muon or tau lepton loop: Their sums are -5.876(802) (alpha/pi)^5 for the Set VI(d), 5.710(490) (alpha/pi)^5 for the Set VI(g), and -8.361(232) (alpha/pi)^5 for the Set VI(h), respectively.Comment: 17 pages, 5 figure

Searching for T,CP,CPT,and \Delta S = \Delta Q rule violations in the neutral K meson system - a guide

It is known that the existing experimental limit for$CPT$ violation is rather poor; the 10 \% level at best. The \DSDQ rule is tested only up to 2 \%. In this note, we discuss the possibility of measuring $T, CP, CPT$ and \DSDQ rule violations in the neutral $K$ meson system. It is shown that not all the symmetry breaking parameters can be determined at a symmetric $\phi$ factory. Experiments with $K^0$ and $\bar{K}^0$ beams are needed to test all the symmetries.Comment: RevTex, 43 pages, DPNU 93-0

On the theoretical uncertainties in the muon anomalous magnetic moment

I present a fairly detailed discussion of various contributions to the anomalous magnetic moment of the muon a_mu. I try to give an unbiased evaluation of the validity of the SM prediction for this quantity and to point out some delicate issues involved in its calculation. I conclude that the theory uncertainties in the SM prediction for the muon anomalous magnetic moment are underestimated and a great deal of work will be required to reduce these uncertainties to the level required by experiment.Comment: 12 pages, revte