86 research outputs found
On the Gauge Fixing of the k Symmetry on AdS and Flat Background: the Lightcone Action for the Type IIb String on AdS_{5} X S_{5}
We explore all the possible ways of fixing the kappa symmetry for both branes
and strings by means of a constant projector. We find that they can be
classified according to their behaviour under Dirac conjugation and
conjugation. This latter controls the maximum power of the fermionic variables
in which the (super)vielbein can be expanded while the former determines which
states cannot be described in the gauge. In particular there exists an
interesting class of projectors for which vielbein are at most quadratic in the
fermionic variables. As an example we compute the action for the type IIb on a
AdS_{5} X S_{5} background with a lightcone-like projector; this action reduces
to the usual lightcone GS string action in the flat limit.Comment: 12+1 pages, latex, no figure
Polymers and Topological Field Theory: A 2 Loop Computation
Within the Quantum Action Principle framework we show the perturbative
renormalizability of previously proposed topological lagrangian \`a la
Witten-Fujikawa describing polymers, then we perform a 2 loop computation. The
theory turns out to have the same predictive power of De Gennes theory, even
though its running coupling constants exhibit a very peculiar behaviour.
Moreover we argue that the theory presents two phases , a topological and a non
topological one.Comment: 17 pages with 5 figures (included), DFTT 29/9
Exact Results for the Supersymmetric Gauge Theories
We study the supersymmetric gauge theories with flavors of
quarks in the fundamental vector representation. We find dynamically generated
superpotentials, smooth quantum moduli space, quantum moduli space with
additional mesons, non trivial IR fixed points.Comment: LaTex, 15 page
The Gross-Neveu model on the light cone
We consider the (massive) Gross-Neveu model using the light cone quantization
where we solve the constraints explicitly. We show that the vacuum is trivial
and that the quantization fails when . We discuss how the running coupling
constant emerges as a pure normal ordering effect in this context and the bound
state equation.Comment: LaTex, 13+1 pages (1 eps Z-compressed figure included
Vector Induced Lattice Gauge Theories
We consider vector induced lattice gauge theories, in particular we consider
the QED induced and we show that at negative temperature corresponds to the
dimer problem while at positive temperature it describes a gas of branched
polymers with loops. We argue that these models are critical at for
and they are {\sl not} critical for .Comment: 9 Pages, plain Latex, NBI-HE-93-0
The generalized Gross-Neveu model on the light cone
We investigate the generalized Gross-Neveu model using the discretized light
cone quantization and we find that the vacuum of the bare theory is {\sl non}
trivial in presence of vectorial current coupling when the simplest and most
natural form of quantum constraints is used. Nevertheless the vacuum of the
renormalized theory is trivial. In the thermodynamic the Bethe-Salpiter
equations which are obtained contain all the terms needed to make them finite.Comment: LaTex, 13 page
Towards a fully stringy computation of Yukawa couplings on non factorized tori and non abelian twist correlators (I): the classical solution and action
We consider the simplest possible setting of non abelian twist fields which
corresponds to monodromies. We first review the theory of
hypergeometric function and of the solutions of the most general Fuchsian
second order equation with three singularities. Then we solve the problem of
writing the general solution with prescribed monodromies. We use this
result to compute the classical string solution corresponding to three
branes in . Despite the fact the configuration is supersymmetric the
classical string solution is not holomorphic. Using the equation of motion and
not the KLT approach we give a very simple expression for the classical action
of the string. We find that the classical action is not proportional to the
area of the triangle determined by the branes intersection points since the
solution is not holomorphic. Phenomenologically this means that the Yukawa
couplings for these supersymmetric configurations on non factorized tori are
suppressed with respect to the factorized case.Comment: 51 pages, 16 figure
Light cone quantization and interactions of a new closed bosonic string inspired to D1 string
We quantize the bosonic part of the D1 string with closed boundary conditions
on the light cone and we consider the U(1) worldsheet gauge field a dynamical
variable. We compute also 3-Reggeon vertex by the overlapping technique. We
find that the Fock space is the sum of sectors characterized by the momentum of
the U(1) Wilson line and that these sectors do not interact among them. Each
sector has exactly the same spectrum of the usual bosonic string when expressed
in properly sector dependent rescaled variables. Rescaling is forced by
factorization of the string amplitudes. We are also able to determine the
relative string coupling constant of the different sectors. It follows a
somewhat unexpected picture in which the effective action is always the same
independently on the sector but string amplitudes are only the same when
expressed in sector dependent rescaled variables.Comment: 17 pages, 2 figure
Correlators of arbitrary untwisted operators and excited twist operators for N branes at angles
We compute the generic correlator with L untwisted operators and N (excited)
twist fields for branes at angles on T^2 and show that it is given by a
generalization of the Wick theorem. We give also the recipe to compute
efficiently the generic OPE between an untwisted operator and an excited
twisted state.Comment: 49 pages, 6 figure
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