496 research outputs found
Application of symbol-operator technique for effective action computation
In the present talk we briefly demonstrate an elegant and effective technique
for calculation of the trace expansion in the derivatives of background fields.
One of main advantages of the technique is manifestly (super)symmetrical and
gauge invariant form of expressions on all stages of calculations. Other
advantage is the universality of the calculation method. Some particular
examples and results are presented.Comment: 11 pages, LaTex, Extended version of the talk given at the Fifth
Workshop on Quantum Field Theory under the Influence of External Conditions,
Leipzig, 10-15 Sept. 200
Currents of quasi-trapped particles and their interaction with the geomagnetic field /symmetrical approximation/
Currents of quasitrapped particles and their interaction with geomagnetic fiel
"Induced" N=4 conformal supergravity
We consider an abelian N=4 super Yang-Mills theory coupled to background N=4
conformal supergravity fields. At the classical level, this coupling is
invariant under global SU(1,1) transformation of the complex ("dilaton-axion")
supergravity scalar combined with an on-shell vector-vector duality. We compute
the divergent part of the corresponding quantum effective action found by
integrating over the super Yang-Mills fields and demonstrate its SU(1,1)
invariance. This divergent part related to the conformal anomaly is one-loop
exact and should be given by the N=4 conformal supergravity action containing
the Weyl tensor squared term. This allows us to determine the full non-linear
form of the bosonic part of the N=4 conformal supergravity action which has
manifest SU(1,1) invariance.Comment: 13 pages. v2: minor misprints corrected; v3: note added about missed
terms in the actio
Carbocycle synthesis via novel organopalladium addition to nitriles
Rarely observed carbopalladation of the cyano group has been investigated. Synthetic methodology for 2,3-diarylindenones by the palladium-catalyzed annulation of alkynes with 2-iodoarenenitriles has been developed. This methodology has also been adapted to the annulation of bicyclic olefins. The reaction affords 2,3-diarylindenones and polycyclic aromatic ketones in very good to excellent yields and tolerates a number of functional groups, making it an efficient synthetic route to these compounds. The reaction is believed to proceed via (1) oxidative addition of the aryl iodide to Pd(0), (2) arylpalladium addition to the carbon-carbon multiple bond, (3) addition of the resulting vinylic or alkylpalladium species across the triple bond of the cyano group to produce an iminopalladium moiety, and (4) hydrolysis of the imine intermediate. A model accounting for the electronic effects of substituents on the aromatic ring of the nitrile has also been proposed.;The palladium-catalyzed annulation of alkynes with iodoarenes containing a cyano group has been extended to the synthesis of 3,4-disubstituted 2-aminonaphthalenes. (2-Iodophenyl)-acetonitrile reacts with a variety of internal alkynes to afford 2-aminonaphthalenes in high yields. In many cases, the regioselectivity of this reaction is excellent. The scope and limitations of this process, which proceeds via a mechanism similar to the reaction between 2-iodoarenenitriles and alkynes, have been studied. When introduced into the reaction, certain hindered propargylic alcohols have been found to afford 1,3-benzoxazine derivatives rather than the expected 2-aminonaphthalenes. The involvement of trialkylamine bases in the formation of these heterocyclic compounds has been established and a mechanism for this transformation has been proposed.;A general and efficient procedure for the synthesis of 2,2-disubstituted indanones by the palladium-catalyzed cyclization of 3-(2-iodoaryl)propanenitriles has been developed. This process is also based on intramolecular carbopalladation of the cyano group. A variety of indanones have been prepared in high yields from readily available starting materials containing various functional groups that are compatible with the reaction conditions. The reaction is not limited to the synthesis of indanones as other benzocyclic ketones, as well as a number of substituted cyclopentenones, have been synthesized by this methodology
One-loop effective potential in generic chiral superfield model
We obtain the one-loop quantum corrections to the K\"ahlerian and
superpotentials in the generic chiral superfield model on the
nonanticommutative superspace. Unlike all previous works, we use a method which
does not require to rewrite a star-product of superfields in terms of ordinary
products. In the K\"ahlerian potential sector the one-loop contributions are
analogous to ones in the undeformed theory while in the chiral potential sector
the quantum corrections contain a deformation parameter.Comment: LaTeX, 9 pages, Typos correcte
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