C. Aragone

Consistency problems of hypergravity

Abstract The constraints arising upon coupling a massless spin 5 2 field to gravity are analyzed. In contrast to supergravity, they depend not only on the Einstein tensor, but also on the off-shell (Weyl) components of the curvature. The latter contributions do vanish, however, for “self-dual” systems, i.e., half-flat gravitational and pure (left/right) helicity spin 5 2 fields.

Intelligent spin states

The intelligent spin states are defined as those states which satisfy the Heisenberg equality for the spin operators: Delta Jx2 Delta Jy2= mod (Jz) mod 2. The 2j+1 states which behave intelligently in each angular momentum space of spin j are found explicitly. For this purpose the Radcliffe states are used, it is shown that only the real and the pure imaginary Radcliffe states are intelligent. These intelligent states also satisfy the quartic consistency condition. The result, however, does not disagree in principle with the recent claim of Kolodziejczyk and Ryter (1974) that mod mu )= mod 0) is the only state which minimizes the uncertainty product because minimum uncertainty does not necessarily imply intelligence.

Higher spin vierbein gauge fermions and hypergravities

The actions describing any massless fermion of spin ⩾52 are given uniformly in terms of non-symmetric vierbein-like fields ψμa…as. Hamiltonian analysis of their dynamical content is performed explicitly for s = 5272, and indicated for the general case. The consistency problems in gravitational coupling are discussed. For spin 52, they are equivalent to those in symmetric tensor-spinor formulation. The general spin case has the same structure: in Minkowski signature, the consistency requirements are too restrictive (vanishing Weyl tensor); their euclidean counterparts require self-duality in both gravity and matter.

On intelligent spin states

In this paper we give a more compact representation of the intelligent spin states defined by Aragone, Guerri, Salamo, and Tani. Using this new representation, we discuss the differences between minimum uncertainty states, coherent Bloch spin states and intelligent states. The evolution of these states under a particular time dependent Hamiltonian is studied, showing the relevance of the noncompact subgroup K of the Lorentz group. Finally we analyze the radiative properties connected with the intelligent states for a pointlike medium. The main results are: (I) they have a nonvanishing dipole moment (as the Bloch states) and (II) the proper intelligent states give a spontaneous emission intensity which is different from the one provided by the Bloch states.

Massive higher spin from dimensional reduction of gauge fields

A unified treatment of symmetric and “D-bein” higher integer spin massive fields in arbitrary dimension is presented and illustrated with the generic cases of spins 3 and 4. The theories are uniformly generated from massless gauge systems in one higher dimension by Kaluza-Klein reduction. The origin and role of various auxiliary field formulations are thereby clarified in terms of the underlying gauge freedom. This treatment is compared with the construction of massive theories from gauge field actions in the same dimension. The general canonical formulation is also exhibited.

Self-dual massive gravity

Abstract The first-order action for self-dual linearized massive gravity in D =3 is given. Also two master actions relevant for this spin-2 case are given, explaining the equivalence between the self-dual formulation and the topological massive one. The evaluation of the vacuum amplitude in the presence of an external current shows in a covariant complementary way the propagation of a unique, parity sensitive, spin-2, massive excitation.

Hypersymmetry in D=3 of coupled gravity-massless spin-5/2 system

In three spacetime dimensions, the coupled massless spin-5/2-Einstein system exhibits a new local supersymmetry parametrised by a vector-spinor rather than a spinor as in supergravity. Although the theory does not contain dynamics, but only torsion, this hypersymmetry still formally ensures consistency. The analysis extends to arbitrary rank fermions.

Geometric stringy gravity

Following the indications that Einsteins gravity is corrected due to superstring effects, we propose a model for even-dimensional gravity that has a very strong geometrical appeal. Its leading correction to Einsteins gravity is the Gauss-Bonnett invariant and for D>6 it also contains all the additional Euler invariants. The model emphasizes the role of two-dimensional subspaces as the elementary building blocks of the higher-dimensional space-time. It is the natural consistent spin-2 generalization of the Born-Infeld (spin-1) action.

Vielbein gravity in the light-front gauge

D-dimensional Einstein gravity is analysed in the light-front gauge in its first-order vielbein formulation. The calculation is performed in an intrinsically vielbein way. The unconstrained action coincides with previous results obtained using the metric formulation. Although the expression for the light-front energy does not appear to be non-negative due to the presence of the D-2 transverse scalar curvature, it is shown, however, that in the linearised approximation it is non-negative being the transverse kinetic energy of a pure helicity-2 excitation. Results are uniformly given for arbitrary D>or=3.

String dynamics from energy momentum conservation

It is shown, without use of a Lagrangian, that conservation alone fixes both the stress tensor and equations of motion of an a priori arbitrary one dimensional δ distribution to be those of the usual Nambu string model.