691 research outputs found
Lorentz-violating Yang-Mills theory: discussing the Chern-Simons-like term generation
We analyze the Chern-Simons-like term generation in the CPT-odd
Lorentz-violating Yang-Mills theory interacting with fermions. Moreover, we
study the anomalies of this model as well as its quantum stability. The whole
analysis is performed within the algebraic renormalization theory, which is
independent of the renormalization scheme. In addition, all results are valid
to all orders in perturbation theory. We find that the Chern-Simons-like term
is not generated by radiative corrections, just like its Abelian version.
Additionally, the model is also free of gauge anomalies and quantum stable.Comment: 16 pages. No figures. Final version to appear in the Eur.Phys.J.
Equivalence between Zwanziger's horizon function and Gribov's no-pole ghost form factor
The ghost form factor entering the Gribov no-pole condition is evaluated till
the third order in the gauge fields. The resulting expression turns out to
coincide with Zwanziger's horizon function implementing the restriction to the
Gribov region in the functional integral.Comment: 9 pp. No figures. Final version to appear in Physics Letters
On the elimination of infinitesimal Gribov ambiguities in non-Abelian gauge theories
An alternative method to account for the Gribov ambiguities in gauge theories
is presented. It is shown that, to eliminate Gribov ambiguities, at
infinitesimal level, it is required to break the BRST symmetry in a soft
manner. This can be done by introducing a suitable extra constraint that
eliminates the infinitesimal Gribov copies. It is shown that the present
approach is consistent with the well established known cases in the literature,
i.e., the Landau and maximal Abelian gauges. The method is valid for gauges
depending exclusively on the gauge field and is restricted to classical level.
However, occasionally, we deal with quantum aspects of the technique, which are
used to improve the results.Comment: 29 pp. No figures. Discussions added. Final version to appear in EPJ
Gribov ambiguities at the Landau -- maximal Abelian interpolating gauge
In a previous work, we presented a new method to account for the Gribov
ambiguities in non-Abelian gauge theories. The method consists on the
introduction of an extra constraint which directly eliminates the infinitesimal
Gribov copies without the usual geometric approach. Such strategy allows to
treat gauges with non-hermitian Faddeev-Popov operator. In this work, we apply
this method to a gauge which interpolates among the Landau and maximal Abelian
gauges. The result is a local and power counting renormalizable action, free of
infinitesimal Gribov copies. Moreover, the interpolating tree-level gluon
propagator is derived.Comment: Several changes: figures removed, typos corrected and discussions
included. 24 pages, to appear in EPJ
A gestão de doenças em sistemas de produção integrada de pêra rocha.
Numa economia global cada vez mais competitiva, ganham as regiões que possam oferecer produtos com caracterÃsticas diferenciadas. Têm sido tentadas diferentes estratégias de combate a doenças da pereira na região do Oeste, nomeadamente contra o pedrado (Venturia pirina Aderh.), o que revela bem a importância da investigação cientÃfica aplicada como motor de progresso regional. Com as diferentes estratégias de combate ao pedrado constatou-se ser possÃvel obter um novo produto que, mantendo o aspecto anterior, apresenta baixo teor em resÃduos fungicidas. É também possÃvel optimizar a data do tratamento por forma a reduzir a incidência da doença em cada perÃodo de infecção.info:eu-repo/semantics/publishedVersio
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