We consider four dimensional N = 1 supersymmetric Type I compactifications on toroidal orbifolds T /Γ. In particular, we focus on the Type I vacua which are perturbative from the orientifold viewpoint, that is, on the compactifications with well defined world-sheet expansion. The number of such models is rather constrained. This allows us to study all such vacua. This, in particular, involves c...

We define a new function-valued inner product on L2(G), called ?-bracket product, where G is a locally compact abelian group and ? is a topological isomorphism on G. We investigate the notion of ?-orthogonality, Bessel's Inequality and ?-orthonormal bases with respect to this inner product on L2(G).

We study the theory of best approximation in tensor product and the direct sum of some lattice normed spacesX_{i}. We introduce quasi tensor product space anddiscuss about the relation between tensor product space and thisnew space which we denote it by X boxtimesY. We investigate best approximation in direct sum of lattice normed spaces by elements which are not necessarily downwardor upward a...

We consider four dimensional N = 1 supersymmetric Type I compactifications on toroidal orbifolds T /Γ. In particular, we focus on the Type I vacua which are perturbative from the orientifold viewpoint, that is, on the compactifications with well defined world-sheet expansion. The number of such models is rather constrained. This allows us to study all such vacua. This, in particular, involves c...

A non-abelian generalisation of a theory of gravity coupled to a 2-form gauge field and a dilaton is found, in which the metric and 3-form field strength are Lie algebra-valued. In the abelian limit, the curvature with torsion is self-dual in four dimensions, or has SU(n) holonomy in 2n dimensions. The coupling to self-dual Yang-Mills fields in 4 dimensions, or their higher dimensional generali...

A non-abelian generalisation of a theory of gravity coupled to a 2-form gauge field and a dilaton is found, in which the metric and 3-form field strength are Lie algebra-valued. In the abelian limit, the curvature with torsion is self-dual in four dimensions, or has SU(n) holonomy in 2n dimensions. The coupling to self-dual Yang-Mills fields in 4 dimensions, or their higher dimensional generali...

For non-Abelian tensor gauge fields we have found an alternative form of duality transformation, which has the property that the direct and the inverse transformations coincide. This duality transformation has the desired property that the direct and the inverse transformations map Lagrangian forms into each other. guttenb(AT)inp.demokritos.gr savvidy(AT)inp.demokritos.gr

For non-Abelian tensor gauge fields of the lower rank we have found an alternative expression for the field strength tensors, which transform homogeneously with respect to the complementary gauge transformations and allow us to construct the dual Lagrangian. jessica(AT)raunvis.hi.is savvidy(AT)inp.demokritos.gr

A Stochastic Quantization Method (in short, SQM)l) was first introduced by Parisi and Wu) as the third quantization method of gauge theories. Their statement is as follows: In this scheme there is no need to fix the gauge degrees of freedom, i.e., no need to introduce any artificial auxiliary fields (ghost and multiplier fields). It is the main advantage of the SQM. It is essentially governed b...