Coloured Polymers

We show that non-oriented coloured polymers (self--avoiding walks with different types of links) are in the same universality class of the ordinary self--avoiding walks, while the oriented coloured are not.Comment: 8 pag., Latex, NBI-HE-93-0

On the Effective Potential of the Dp- anti Dp system in type II theories

We compute the effective potential of a system composed by a Dp brane and a separated anti-Dp brane at tree level in string theory. We show explicitly that the tachyon condenses and that the scalars which describe transverse fluctuations acquire a VEV proportional to the distance.Comment: latex2e, 1+19 pages Corrected typos. Added criticisms to the previous interpration of the results and a new interpretatio

All roads lead to Rome: Supersolvable and Supercosets

We show explicitly that the two recently proposed actions for the type IIB superstring propagating on AdS_{5} X S_{5} agree completely

Some remarks on the free fields realization of the bosonic string on AdS3AdS_{3}

We discuss the classical solutions of the equations of motion and thepossible boundary condition for a bosonic string with Kalb-Ramond background inAdS3. It turns out that there exists three different physical sectors and thatit is also possible to describe the motion on an extremal black holebackground. The existence of three sectors clearly shows how one of the spectraproposed is incomplete. We consider also the classical 'canonical'transformation which maps the string fields to the classical Wakimoto ones. Itturns however out that the Wakimoto fields are not free because of the boundaryconditions and in order to have the usual mode expansion with reasonablebehaviour under complex conjugation it is necessary to consider thecomplexification of AdS3 and then add some constraints. Furthermore they coveronly half AdS3 and we need different patches to cover the whole space and tomake the above mentioned transformation really canonical

The Master Field of QCD2_2 and the 'T Hooft Equation

We rewrite the action for $QCD_2$ in the light cone gauge only in terms of a bilocal mesonic field. In this formalism the $1/N$ expansion can be done in a straightforward way by a saddle point technique that determines the master field to be identified with the vacuum expectation value of the bilocal field. Finally we show that the equation of motion for the fluctuations around the master field is identical with the 't Hooft meson equation.Comment: 7 pages, Latex, NORDITA-93-4

Partial N=2 --> N=1 Local Supersymmetry Breaking and Solvable Lie Algebras

Generic partial supersymmetry breaking of N=2 supergravity with zero vacuum energy and with surviving unbroken arbitrary gauge groups is exhibited. Specific examples are given.Comment: 5 pages, 1 LaTeX-style file, 1 TeX, 2 Postscript figures. Seminar given at the Work-Shop on "Gauge Theories, Applied Supersymmetry and Quantum Gravity", Imperial College, London, 5-10 July 199