784 research outputs found
Non-renormalization of two and three Point Correlators of N=4 SYM in N=1 Superspace
Certain two and three point functions of gauge invariant primary operators of
SYM are computed in superspace keeping all the
-components. This allows one to read off many component descendent
correlators. Our results show the only possible corrections to the
free field correlators are contact terms. Therefore they vanish for operators
at separate points, verifying the known non-renormalization theorems. This also
implies the results are consistent with supersymmetry even though
the Lagrangian we use has only manifest supersymmetry. We repeat
some of the calculations using supersymmetric Landau gauge and obtain, as
expected, the same results as those of supersymmetric Feynman gauge.Comment: 10 pages, 20 eps figures, references adde
Nonholomorphic N=2 terms in N=4 SYM: 1-Loop Calculation in N=2 superspace
The effective action of N=2 gauge multiplets in general includes
higher-dimension UV finite nonholomorphic corrections integrated with the full
N=2 superspace measure. By adding a hypermultiplet in the adjoint
representation we study the effective action of N=4 SYM. The nonanomalous SU(4)
R-symmetry of the classical N=4 theory must be also present in the on-shell
effective action, and therefore we expect to find similar nonholomorphic terms
for each of the scalars in the hypermultiplet. The N=2 path integral
quantization formalism developed in projective superspace allows us to compute
these hypermultiplet nonholomorphic terms directly in N=2 superspace. The
corresponding gauge multiplet expression can be successfully compared with the
result inferred from a N=1 calculation in the abelian subsector.Comment: 12 pages, LaTex, includes 4 .eps figures, sign convention in path
integral definition changed, sign of nonholomorphic potential change
On N=2 low energy effective actions
We propose a Wilsonian action compatible with special geometry and higher
dimension N=2 corrections, and show that the holomorphic contribution F to the
low energy effective action is independent of the infrared cutoff. We further
show that for asymptotically free SU(2) super Yang-Mills theories, the infrared
cutoff can be tuned to cancel leading corrections to F. We also classify all
local higher-dimensional contributions to the N=2 superspace effective action
that produce corrections to the Kahler potential when reduced to N=1
superspace.Comment: 9 pages, Late
Non-renormalization of next-to-extremal correlators in N=4 SYM and the AdS/CFT correspondence
We show that next-to-extremal correlators of chiral primary operators in N=4
SYM theory do not receive quantum corrections to first order in perturbation
theory. Furthermore we consider next-to-extremal correlators within AdS
supergravity. Here the exchange diagrams contributing to these correlators
yield results of the same free-field form as obtained within field theory. This
suggests that quantum corrections vanish at strong coupling as well.Comment: 21 pages, LaTex, 9 eps figures, typos corrected and references adde
Soil and water bioengineering: practice and research needs for reconciling natural hazard control and ecological restoration
Soil and water bioengineering is a technology that encourages scientists and practitioners to combine their knowledge and skills in the management of ecosystems with a common goal to maximize benefits to both man and the natural environment. It involves techniques that use plants as living building materials, for: (i) natural hazard control (e.g., soil erosion, torrential floods and landslides) and (ii) ecological restoration or nature-based re-introduction of species on degraded lands, river embankments, and disturbed environments. For a bioengineering project to be successful, engineers are required to highlight all the potential benefits and ecosystem services by documenting the technical, ecological, economic and social values. The novel approaches used by bioengineers raise questions for researchers and necessitate innovation from practitioners to design bioengineering concepts and techniques. Our objective in this paper, therefore, is to highlight the practice and research needs in soil and water bioengineering for reconciling natural hazard control and ecological restoration. Firstly, we review the definition and development of bioengineering technology, while stressing issues concerning the design, implementation, and monitoring of bioengineering actions. Secondly, we highlight the need to reconcile natural hazard control and ecological restoration by posing novel practice and research questions
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