Signals for Noncommutative QED at Future e+e−e^+e^- Colliders

The signatures for noncommutative QED at $e^+e^-$ colliders with center of mass energies in the range of 0.5-5 TeV are examined. For integrated luminosities of 0.5-1 ab$^{-1}$ or more, sensitivities to the associated mass scales greater than $\sqrt s$ are possible.Comment: LaTex, 6 pages, 6 figs; to appear in the Proceedings of the Fourth International Workshop on $e^-e^-$ Interactions at TeV Energies, UC Santa Cruz, 7-9 Dec 200

Noncommutative QED and Anomalous Dipole Moments

We study QED on noncommutative spaces, NCQED. In particular we present the detailed calculation for the noncommutative electron-photon vertex and show that the Ward identity is satisfied. We discuss that in the noncommutative case moving electron will show {\it electric} dipole effects. In addition, we work out the electric and magnetic dipole moments up to one loop level. For the magnetic moment we show that noncommutative electron has an intrinsic (spin independent) magnetic moment.Comment: 27 pages, several .ps and .eps figures, v3:typos in some formula corrected, version appeared in JHE

Noncommutative Space Corrections on the Klein-Gordon and Dirac Oscillators Spectra

We consider the influence of a noncommutative space on the Klein-Gordon and the Dirac oscillators. The nonrelativistic limit is taken and the $\theta$-modified Hamiltonians are determined. The corrections of these Hamiltonians on the energy levels are evaluated in first-order perturbation theory. It is observed a total lifting of the degeneracy to the considered levels. Such effects are similar to the Zeeman splitting in a commutative space.Comment: 15 pages, 2 figures, improvements and changes are added, Final version published in IJMP

Photon deflection by a Coulomb field in noncommutative QED

In noncommutative QED photons present self-interactions in the form of triple and quartic interactions. The triple interaction implies that, even though the photon is electrically neutral, it will deflect when in the presence of an electromagnetic field. If detected, such deflection would be an undoubted signal of noncommutative space-time. In this work we derive the general expression for the deflection of a photon by any electromagnetic field. As an application we consider the case of the deflection of a photon by an external static Coulomb field.Comment: 07 pages, some typos corrected, accepted for publication in JP

One-loop renormalization of general noncommutative Yang-Mills field model coupled to scalar and spinor fields

We study the theory of noncommutative U(N) Yang-Mills field interacting with scalar and spinor fields in the fundamental and the adjoint representations. We include in the action both the terms describing interaction between the gauge and the matter fields and the terms which describe interaction among the matter fields only. Some of these interaction terms have not been considered previously in the context of noncommutative field theory. We find all counterterms for the theory to be finite in the one-loop approximation. It is shown that these counterterms allow to absorb all the divergencies by renormalization of the fields and the coupling constants, so the theory turns out to be multiplicatively renormalizable. In case of 1PI gauge field functions the result may easily be generalized on an arbitrary number of the matter fields. To generalize the results for the other 1PI functions it is necessary for the matter coupling constants to be adapted in the proper way. In some simple cases this generalization for a part of these 1PI functions is considered.Comment: 1+26 pages, figures using axodraw, clarifications adde

Review of the Phenomenology of Noncommutative Geometry

We present a pedagogical review of particle physics models that are based on the noncommutativity of space-time, $[\hat{x}_\mu,\hat{x}_\nu]=i \theta_{\mu \nu}$, with specific attention to the phenomenology these models predict in particle experiments either in existence or under development. We summarize results obtained for high energy scattering such as would occur for example in a future $e^+e^-$ linear collider with $\sqrt{s} = 500 GeV$, as well as low energy experiments such as those pertaining to elementary electric dipole moments and other \cpviolng observables, and finally comment on the status of phenomenological work in cosmology and extra dimensions.Comment: updated, references added, corrected typo

Positronium Hyperfine Splitting in Non-commutative Space at the Order α6\alpha^6

We obtain positronium Hyperfine Splitting owing to the non-commutativity of space and show that, in the leading order, it is proportional to $\theta \alpha^6$ where, $\theta$ is the parameter of non-commutativity. It is also shown that spatial non-commutativity splits the spacing between $n=2$ triplet excited levels $E(2^3S_1)\to E(2^3P_2)$ which provides an experimental test on the non-commutativity of space.Comment: 7 pages, 2 figures, to appear in Phys. Rev.

Flat Cosmology with Coupled Matter and Dark Energies

Three models of a flat universe of coupled matter and dark energies with different low-redshift parameterizations of the dark energy equation of state are considered. The dark energy is assumed to vary with time like the trace of the energy-momentum tensor of cosmic matter. In the radiation-dominated era the models reduce to standard cosmology. In the matter-dominated era they are, for modern values of the cosmological parameters, consistent with data from SNe Ia searches and with the data of Gurvits et al.(1999)for angular sizes of ultra compact radio sources. We find that the angular size-redshift tests for our models offer a higher statistical confidence than that based on SNe Ia data. A comparison of our results with a recent revised analysis of angular size-redshift legacy data is made,and the implications of our models with optimized relativistic beaming in the radio sources is discussed. In particular we find that relativistic beaming implies a Lorentz factor less than 6,in agreement with its values for powerful Active Galactic Nuclei.Comment: Version to appear in The Astronomical Journal, with a modified name- Flat Cosmology with Coupled Matter and Dark Energies. Expanded and Modified conten

Compton scattering in Noncommutative Space-Time at the NLC

We study the Compton scattering in the noncommutative counter part of QED (NC QED). Interactions in NC QED have momentum dependent phase factors and the gauge fields have Yang Mills type couplings, this modifies the cross sections and are different from the commuting Standard Model. Collider signals of noncommutative space-time are studied at the Next Linear Collider (NLC) operating in the $e \gamma$ mode. Results for different polarised cases are presented and it is shown that the Compton process can probe the noncommutative scale in the range of 1 - 2.5 TeV for typical proposed NLC energies.Comment: 12 pages, 5 Postscript figures, version to appear in Phys. Rev.