14 research outputs found
Pinch Technique: Theory and Applications
We review the theoretical foundations and most important physical
applications of the Pinch Technique (PT). This method allows the construction
of off-shell Green's functions in non-Abelian gauge theories that are
independent of the gauge-fixing parameter and satisfy ghost-free Ward
identities. We first present the diagrammatic formulation of the technique in
QCD, deriving at one loop the gauge independent gluon self-energy, quark-gluon
vertex, and three-gluon vertex, together with their Abelian Ward identities.
The generalization to theories with spontaneous symmetry breaking is carried
out in detail, and the connection with the optical theorem and the dispersion
relations are explained within the electroweak sector of the Standard Model.
The equivalence between the PT and the Feynman gauge of the Background Field
Method (BFM) is elaborated, and the crucial differences between the two methods
are critically scrutinized. The Batalin-Vilkovisky quantization method and the
general formalism of algebraic renormalization are introduced, and the
all-order generalization of the PT is thoroughly examined. The extension of the
PT to the non-perturbative domain of the QCD Schwinger-Dyson equations is
presented systematically, and the main advantages of the resulting
self-consistent truncation scheme are discussed. A plethora of physical
applications relying on the PT are reviewed, such as the definition of
gauge-independent off-shell form-factors, the construction of non-Abelian
effective charges, the gauge-invariant treatment of resonant transition
amplitudes and unstable particles, and the dynamical generation of an effective
gluon mass.Comment: 245 pages, 92 figure
There is more than one 'killer shrimp': trophic positions and predatory abilities of invasive amphipods of Ponto-Caspian origin
Contains fulltext :
111449.pdf (publisher's version ) (Closed access
Autecology of Limnomysis benedeni Czerniavsky, 1882 (Crustacea: Mysida) in Lake Constance, Southwestern Germany
Global Estimates of the Prevalence and Incidence of Four Curable Sexually Transmitted Infections in 2012 Based on Systematic Review and Global Reporting
Potential alteration of cross-ecosystem resource subsidies by an invasive aquatic macroinvertebrate: implications for the terrestrial food web
Long-term trends in trait structure of riverine communities facing predation risk increase and trophic resource decline
Invasive alien Crustacea: dispersal, establishment, impact and control
The subphylum Crustacea includes the most successful species among aquatic alien invaders. The impacts
of invasive alien crustaceans (IAC) are often substantial, due to the complex trophic role of most of these
species leading to cascading effects throughout the invaded ecosystems. IAC also have the potential to cause
a shift in the âkeystoneâ ecosystem functions, changing energy flux and nutrient cycles which together affect
critical ecosystem services such as biodiversity, fisheries yield and water quality. Although no individual trait
appears to be a good predictor of invasion success, a combination of some characteristics such as
eurytolerance, omnivory and certain r -selected life-history traits results in a high probability of alien
crustacean species becoming invasive. Both environmental factors, such as habitat heterogeneity in the
invaded ecosystems, and evolutionary factors, such as adaptations to new environmental conditions, also play
important roles during establishment. Therefore, individual environmental niche models, including genetic
algorithm, have the highest likelihood of providing useful predictive information about invasion success and
spread of alien Crustacea. Attempts to control IAC through biocides or mechanical removal have had mixed
success in the past but a strategic combination of different methods may lead to some success in the future