Effective gravity and OSp(N,4) invariant matter

We re-examine the OSp(N,4) invariant interacting model of massless chiral and gauge superfields, whose superconformal invariance was instrumental, both in proving the all-order no-renormalization of the mass and chiral self-interaction lagrangians, and in determining the linear superfield renormalization needed. We show that the renormalization of the gravitational action modifies only the cosmological term, without affecting higher-order tensors. This could explain why the effect of the cosmological constant is shadowed by the effects of newtonian gravity.Comment: 12 pages, LaTeX, 4 figures, PACS: 04.65.+e, substantial revisions, to appear in Phys. Rev.

N=4 supersymmetric mechanics with nonlinear chiral supermultiplet

We construct N=4 supersymmetric mechanics using the N=4 nonlinear chiral supermultiplet. The two bosonic degrees of freedom of this supermultiplet parameterize the sphere S(2) and go into the bosonic components of the standard chiral multiplet when the radius of the sphere goes to infinity. We construct the most general action and demonstrate that the nonlinearity of the supermultiplet results in the deformation of the connection, which couples the fermionic degrees of freedom with the background, and of the bosonic potential. Also a non-zero magnetic field could appear in the system.Comment: 5 page

Hyper-Kaehler geometry and dualization

We demonstrate that in N=8 supersymmetric mechanics with linear and nonlinear chiral supermultiplets one may dualize two auxiliary fields into physical ones in such a way that the bosonic manifold will be a hyper-Kaehler one. The key point of our construction is about different dualizations of the two auxiliary components. One of them is turned into a physical one in the standard way through its replacement by the total time derivative of some physical field. The other auxiliary field is dualized through a Lagrange multiplier. We clarify this choice of dualization by presenting the analogy with a three-dimensional case.Comment: 9 pages, LaTeX file, PACS numbers: 11.30.Pb, 03.65.-

A modification of the 10d superparticle action inspired by the Gupta-Bleuler quantization scheme method

We reconsider the issue of the existence of a complex structure in the Gupta-Bleuler quantization scheme. We prove an existence theorem for the complex structure associated with the $d=10$ Casalbuoni-Brink-Schwarz superparticle, based on an explicitly constructed Lagrangian that allows a holomorphic-antiholomorphic splitting of the fermionic constraints consistent with the vanishing of all first class constraints on the physical states.Comment: 7 pages, LaTeX, to appear in Phys. Lett.

Universal Superfield Action for N=8→N=4N=8 \to N=4 Partial Breaking of Global Supersymmetry in D=1

We explicitly construct N=4 worldline supersymmetric minimal off-shell actions for five options of 1/2 partial spontaneous breaking of $N=8, d=1$ Poincar\'e supersymmetry. We demonstrate that the action for the N=4 Goldstone supermultiplet with four fermions and four auxiliary components is a universal one. The remaining actions for the Goldstone supermultiplets with physical bosons are obtained from the universal one by off-shell duality transformations.Comment: 9 pages, LaTeX file, PACS numbers: 11.30.Pb, 03.65.-

Superfield Formulation of Nonlinear N=4 Supermultiplets

We propose a unified superfield formulation of N=4 off-shell supermultiplets in one spacetime dimension using the standard N=4 superspace. The main idea of our approach is a "gluing" together of two linear supermultiplets along their fermions. The functions defining such a gluing obey a system of equations. Each solution of this system provides a new supermultiplet, linear or nonlinear, modulo equivalence transformations. In such a way we reproduce all known linear and nonlinear N=4, d=1 supermultiplets and propose some new ones. Particularly interesting is an explicit construction of nonlinear N=4 hypermultiplets.Comment: 16 pages, no figure

Hamiltonian reduction and supersymmetric mechanics with Dirac monopole

We apply the technique of Hamiltonian reduction for the construction of three-dimensional ${\cal N}=4$ supersymmetric mechanics specified by the presence of a Dirac monopole. For this purpose we take the conventional ${\cal N}=4$ supersymmetric mechanics on the four-dimensional conformally-flat spaces and perform its Hamiltonian reduction to three-dimensional system. We formulate the final system in the canonical coordinates, and present, in these terms, the explicit expressions of the Hamiltonian and supercharges. We show that, besides a magnetic monopole field, the resulting system is specified by the presence of a spin-orbit coupling term. A comparison with previous work is also carried out.Comment: 9 pages, LaTeX file, PACS numbers: 11.30.Pb, 03.65.-w, accepted for publication in PRD; minor changes in the Conclusion, the Bibliography and the Acknowledgemen