Exterior Differentials in Superspace and Poisson Brackets

It is shown that two definitions for an exterior differential in superspace, giving the same exterior calculus, yet lead to different results when applied to the Poisson bracket. A prescription for the transition with the help of these exterior differentials from the given Poisson bracket of definite Grassmann parity to another bracket is introduced. It is also indicated that the resulting bracket leads to generalization of the Schouten-Nijenhuis bracket for the cases of superspace and brackets of diverse Grassmann parities. It is shown that in the case of the Grassmann-odd exterior differential the resulting bracket is the bracket given on exterior forms. The above-mentioned transition with the use of the odd exterior differential applied to the linear even/odd Poisson brackets, that correspond to semi-simple Lie groups, results, respectively, in also linear odd/even brackets which are naturally connected with the Lie superalgebra. The latter contains the BRST and anti-BRST charges and can be used for calculation of the BRST operator cohomology.Comment: 12 pages, LATEX 2e, JHEP format. Correction of misprints. The titles for some references are adde

The geometry of supersymmetric coset models and superconformal algebras

An on-shell formulation of (p,q), 2\leq p \leq 4, 0\leq q\leq 4, supersymmetric coset models with target space the group G and gauge group a subgroup H of G is given. It is shown that there is a correspondence between the number of supersymmetries of a coset model and the geometry of the coset space G/H. The algebras of currents of supersymmetric coset models are superconformal algebras. In particular, the algebras of currents of (2,2) and (4,0) supersymmetric coset models are related to the N=2 Kazama-Suzuki and N=4 Van Proeyen superconformal algebras correspondingly.Comment: pages 2

Investigating fission distribution behavior under various homogenization techniques for asymmetrical fuel assemblies and different reflector equivalence methods

International audienceThis article provides an analysis of asymmetrical assemblies homogenization, based on the first startup of the BEAVRS benchmark v2.0.2, in Hot Zero Power state (HZP). We use a classical two-step simulation with the deterministic codes DRAGON5 and DONJON5. First a transport calculation is performed with DRAGON5 on fuel assemblies, based on previous work conducted at the Polytechnique Montréal. Then, the complete core calculation is done with DONJON5 using a two-group energy mesh, in diffusion theory. The fission rates are calculated using DONJON5 and compared to the in-core detectors data provided in the BEAVRS benchmark. Discrepancies between the simulation and radial adjusted measurements present a Root Mean Square error (RMS) discrepancy of ≃ 4.5% (with relative errors lower than 10%). The results show the necessity to consider heterogeneity when it comes to model assemblies without central symmetry