Mapping the geometry of the E6 group

In this paper we present a construction for the compact form of the exceptional Lie group E6 by exponentiating the corresponding Lie algebra e6, which we realize as the the sum of f4, the derivations of the exceptional Jordan algebra J3 of dimension 3 with octonionic entries, and the right multiplication by the elements of J3 with vanishing trace. Our parametrization is a generalization of the Euler angles for SU(2) and it is based on the fibration of E6 via a F4 subgroup as the fiber. It makes use of a similar construction we have performed in a previous article for F4. An interesting first application of these results lies in the fact that we are able to determine an explicit expression for the Haar invariant measure on the E6 group manifold.Comment: 30 page

Symmetries of an Extended Hubbard Model

An extended Hubbard model with phonons is considered on a D-dimensional lattice. The symmetries of the model are studied in various cases. It is shown that for a certain choice of the parameters a superconducting SU_q(2) holds as a true quantum symmetry - but only for D=1. In a natural basis the symmetry requires vanishing local phonon coupling; a quantum symmetric Hubbard model without phonons can then be obtained by a mean field approximation.Comment: plain tex, 7 page

q-Deformed Minkowski Space based on a q-Lorentz Algebra

The Hilbert space representations of a non-commutative q-deformed Minkowski space, its momenta and its Lorentz boosts are constructed. The spectrum of the diagonalizable space elements shows a lattice-like structure with accumulation points on the light-cone.Comment: 31 pages, 1 figur

Some remarks on unilateral matrix equations

We briefly review the results of our paper hep-th/0009013: we study certain perturbative solutions of left-unilateral matrix equations. These are algebraic equations where the coefficients and the unknown are square matrices of the same order, or, more abstractly, elements of an associative, but possibly noncommutative algebra, and all coefficients are on the left. Recently such equations have appeared in a discussion of generalized Born-Infeld theories. In particular, two equations, their perturbative solutions and the relation between them are studied, applying a unified approach based on the generalized Bezout theorem for matrix polynomials.Comment: latex, 6 pages, 1 figure, talk given at the euroconference "Brane New World and Noncommutative Geometry", Villa Gualino, Torino, Italy, Oct 2-7, 200

Il paesaggio e i gesti del sacro: i casi di Pontecagnano e Monte Vetrano (Salerno)

Pontecagnano and the site of Monte Vetrano in the Agro Picentino provide some interesting cases for reconstructing cult practices and ritual actions integrated into the frame of the landscape: the paper reports the results of the excavations carried out in the two settlements for the construction of the third lane of the highway Salerno-Reggio Calabria and the WTE plant of Salerno

On the Euler angles for SU(N)

In this paper we reconsider the problem of the Euler parametrization for the unitary groups. After constructing the generic group element in terms of generalized angles, we compute the invariant measure on SU(N) and then we determine the full range of the parameters, using both topological and geometrical methods. In particular, we show that the given parametrization realizes the group $SU(N+1)$ as a fibration of U(N) over the complex projective space $\mathbb{CP}^n$. This justifies the interpretation of the parameters as generalized Euler angles.Comment: 16 pages, references adde

Una festa etrusca per Dioniso?

The paper aims to analyze the figurative program of an Etruscan black-figure amphora in Dresden, decorated on one side with a scene of sacrifice in the presence of a satyr, and on the other, with the representation of an armed dance. The assumption is that the amphora is the product of a special commission to celebrate a successful performance as a small triumph, using the mythical paradigm of the Gigantomachy of Heracles as a model