133 research outputs found
A Generalization of Poisson-Nijenhuis Structures
We generalize Poisson-Nijenhuis structures. We prove that on a manifold
endowed with a Nijenhuis tensor and a Jacobi structure which are compatible,
there is a hierarchy of pairwise compatible Jacobi structures.
Furthermore, we study the homogeneous Poisson-Nijenhuis structures and their
relations with Jacobi structures.Comment: 21 pages, Late
Reduction of Jacobi manifolds via Dirac structures theory
We first recall some basic definitions and facts about Jacobi manifolds,
generalized Lie bialgebroids, generalized Courant algebroids and Dirac
structures. We establish an one-one correspondence between reducible Dirac
structures of the generalized Lie bialgebroid of a Jacobi manifold
for which 1 is an admissible function and Jacobi quotient
manifolds of . We study Jacobi reductions from the point of view of Dirac
structures theory and we present some examples and applications.Comment: 18 page
AV-Courant algebroids and generalized CR structures
We construct a generalization of Courant algebroids which are classified by
the third cohomology group , where is a Lie Algebroid, and is
an -module. We see that both Courant algebroids and
structures are examples of them. Finally we introduce generalized CR structures
on a manifold, which are a generalization of generalized complex structures,
and show that every CR structure and contact structure is an example of a
generalized CR structure.Comment: 18 page
Jacobi quasi-Nijenhuis Algebroids
In this paper, for a Jacobi algebroid , by introducing the notion of
Jacobi quasi-Nijenhuis algebroids, which is a generalization of Poisson
quasi-Nijenhuis manifolds introduced by Sti\'{e}non and Xu, we study
generalized complex structures on the Courant-Jacobi algebroid ,
which unifies generalized complex (contact) structures on an
even(odd)-dimensional manifold.Comment: 17 pages, no figur
1-Methyl-1-azonia-3,5-diaza-7-phosphatricyclo[3.3.1.13,7]decane tetrafluoroborate
The title compound, C7H15N3P+·BF4
− or [PTA-Me][BF4], is the N-methylated derivative of the well known water-soluble aminophosphine 1,3,5-triaza-7-phosphaadamantane (PTA). The asymmetric unit consists of a cage-like cation [PTA-Me]+ and a disordered tetrafluoroborate anion; two F atoms are disordered equally over two sites. A network of weak intermolecular C—H⋯F hydrogen bonds results in a three-dimensional supramolecular assembly
Synthesis, characterization and redox behaviour of benzoyldiazenido- and oxorhenium complexes bearing N,N- and S,S-type ligands
The reactions of [ReCl2{eta(2)-N2C(O)Ph}(PPh3)(2)](1) with 2-aminopyrimidine (H(2)Npyrm), 2,2'-bipyridine (bpy) and tetraethylthiuram disulfide (tds), in MeOH upon reflux, lead to the new eta(1)-(benzoyldiazenido)-rhenium(III) complexes [ReCl{eta(1)-N2C(O)Ph}(HNpyrm)(PPh3)(2)](2)and [ReCl2{eta(1)-N2C(O)Ph}(bpy)(PPh3)] (3), and the known oxo(diethyldithiocarbamato)dirhenium(v)complex [Re2O2(mu O){Et2NC(S)S}(4)](4), respectively. The Et2NC(S)S ligands in 4 result from S-S bond rupture of tds molecules. The obtained compounds have been characterized by IR, H-1, P-31{H-1} and C-13{H-1} NMR spectroscopies, FAB(+)-MS, elemental and single-crystal X-ray diffraction (for 2 and 4)analyses. Complex 2 represents the first structurally characterized Re compound derived from 2-aminopyrimidine. Besides, the redox behaviour of 2-4 in CH2Cl2 solution has been studied by cyclic voltammetry, and the Lever electrochemical ligand parameter (E-L)has been estimated, for the first time, for HNpyrm. The electrochemical results are discussed in terms of electronic properties of the Re centres and the ligands
Three-dimensional hydrogen-bonded supramolecular assembly in tetrakis(1,3,5-triaza-7-phosphaadamantane)copper(I) chloride hexahydrate
The structure of the title compound, [Cu(PTA)4]Cl·6H2O (PTA is 1,3,5-triaza-7-phosphaadamantane, C6H12N3P), is composed of discrete monomeric [Cu(PTA)4]+ cations, chloride anions and uncoordinated water molecules. The CuI atom exhibits tetrahedral coordination geometry, involving four symmetry-equivalent P–bound PTA ligands. The structure is extended to a regular three-dimensional supramolecular framework via numerous equivalent O—H⋯N hydrogen bonds between all solvent water molecules (six per cation) and all PTA N atoms, thus simultaneously bridging each [Cu(PTA)4]+ cation with 12 neighbouring units in multiple directions. The study also shows that PTA can be a convenient ligand in crystal engineering for the construction of supramolecular architectures
Upper limits for a narrow resonance in the reaction p + p -> K^+ + (Lambda p)
The reaction pp -> K^+ + (Lambda p) has been measured at T_p = 1.953 GeV and
\Theta = 0 deg with a high missing mass resolution in order to study the Lambda
p final state interaction. Narrow S = -1 resonances predicted by bag model
calculations are not visible in the missing mass spectrum. Small structures
observed in a previous experiment are not confirmed. Upper limits for the
production cross section of a narrow resonance are deduced for missing masses
between 2058 and 2105 MeV/c^2.Comment: 8 pages, 5 figure
Cross section of the reaction close to threshold
We have measured inclusive data on -meson production in collisions
at COSY J\"ulich close to the hyperon production threshold and determined the
hyperon-nucleon invariant mass spectra. The spectra were decomposed into three
parts: , and . The cross section for the
channel was found to be much smaller than a previous measurement in
that excess energy region. The data together with previous results at higher
energies are compatible with a phase space dependence.Comment: accepted by Phys. lett. B some typos correcte
High resolution study of the Lambda p final state interaction in the reaction p + p -> K+ + (Lambda p)
The reaction pp -> K+ + (Lambda p) was measured at Tp=1.953 GeV and Theta = 0
deg with a high missing mass resolution in order to study the Lambda p final
state interaction. The large final state enhancement near the Lambda p
threshold can be described using the standard Jost-function approach. The
singlet and triplet scattering lengths and effective ranges are deduced by
fitting simultaneously the Lambda p invariant mass spectrum and the total cross
section data of the free Lambda p scattering.Comment: submitted to Physics Letters B, 10 pages, 3 figure
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