686 research outputs found
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
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
Biocontrol of cantaloupe damping-off disease caused by Fusarium semitectum by using formulations of antagonistic fungi
oai:ojs.ppmj.net:article/2Antagonistic capability of 19 isolates of fungi isolated from rizosphere of cantaloupe plants was tested in vitro against growth of Fusarium semitectum isolate the causal pathogen of damping- off of cantaloupe. Trichoderma viride (isolate no. 17), T. harzianum (isolate no. 19) and Fusarium concolar (isolate no.4) showed significant percentage of inhibition against to F. semitectum. The effect of carrier formulations of antagonistic fungi (talc based powder and rice bran) on damping-off of cantaloupe were tested under greenhouse and field conditions. In greenhouse experiments, application of antagonistic fungi with rice bran formulation two weeks before planting caused the highest percentage of survival plants in pre and post damping-off (83.33 and 75%, respectively), whereas application of talc based powder formulation significantly increased percentage of plant survival at the time of planting in pre and post damping-off (91.67 and 75%, respectively). In field experiments, application of tested formulations of antagonistic fungi to infested soil with F. semitectum two weeks before planting resulted in higher percentage of plant survival in pre and post damping-off in both teste
Fork-Coupled Resonators for High Frequency Characterization of Dielectric Substrate Materials
Abstract—Efficient coupling of energy in and out of a resonator can significantly enhance its performance, particularly when used for dielectric characterization of materials. In this paper, a new microstrip resonator is introduced, which uses fork-shaped feed elements for improving the coupling efficiency. The proposed resonator is studied both experimentally and theoretically with field simulation software. An important advantage of the fork microstrip resonator is attributed to its single-layer geometry and easier manufacturing processes. This resonator is used to characterize three different dielectric materials. Comparison of measurement results from the fork resonator with those obtained with a stripline resonator suggests that the proposed resonator offers a superior performance
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
Fork-Coupled Resonators for High Frequency Characterization of Dielectric Substrate Materials
Abstract—Efficient coupling of energy in and out of a resonator can significantly enhance its performance, particularly when used for dielectric characterization of materials. In this paper, a new microstrip resonator is introduced, which uses fork-shaped feed elements for improving the coupling efficiency. The proposed resonator is studied both experimentally and theoretically with field simulation software. An important advantage of the fork microstrip resonator is attributed to its single-layer geometry and easier manufacturing processes. This resonator is used to characterize three different dielectric materials. Comparison of measurement results from the fork resonator with those obtained with a stripline resonator suggests that the proposed resonator offers a superior performance
Positronium Hyperfine Splitting in Non-commutative Space at the Order
We obtain positronium Hyperfine Splitting owing to the non-commutativity of
space and show that, in the leading order, it is proportional to where, is the parameter of non-commutativity. It is also
shown that spatial non-commutativity splits the spacing between triplet
excited levels which provides an experimental test on
the non-commutativity of space.Comment: 7 pages, 2 figures, to appear in Phys. Rev.
Comments on Non-Commutative Phenomenology
It is natural to ask whether non-commutative geometry plays a role in four
dimensional physics. By performing explicit computations in various toy models,
we show that quantum effects lead to violations of Lorentz invariance at the
level of operators of dimension three or four. The resulting constraints are
very stringent.Comment: Correction of an error in the U(1) and U(N) calculation leads to
stronger limits than those given previously Clarifying comments and reference
adde
Renormalizability of noncommutative SU(N) gauge theory
We analyze the renormalizability properties of pure gauge noncommutative
SU(N) theory in the -expanded approach. We find that the theory is
one-loop renormalizable to first order in .Comment: 11 pages, minor changes, accepted for publication in JHE
- …