20,226 research outputs found
Non-Integrability of Two-Dimensional QCD
In this paper we numerically demonstrate that massless two-dimensional QCD is
not integrable. To this aim, we explicitly solve the 't Hooft integral equation
for bound states by an adaptive spline procedure, and compute the decay
amplitudes. These amplitudes significantly differ from zero except in all cases
in which the decay also produces a pion.Comment: 9 pages, 6 encapsulated Postscript figures, uses epsfi
Non-linear Brane Dynamics in 6 Dimensions
We consider a dynamical brane world in a six dimensional spacetime containing
a singularity. Using the Israel conditions we study the motion of a 4-brane
embedded in this setup. We analize the brane behavior when its position is
perturbed about a fixed point and solve the full non-linear dynamics in the
several possible scenarios. We also investigate the possible gravitational
shortcuts and calculate the delay between graviton and photon signals and the
ratio of the corresponding subtended horizons.Comment: 5 pages, 2 figures. Contribution to the Proceedings of
"Renormalization Group and Anomalies in Gravitation and Cosmology", Ouro
Preto, Brazil, March 200
Gravitational Interactions of integrable models
We couple non-linear -models to Liouville gravity, showing that
integrability properties of symmetric space models still hold for the matter
sector. Using similar arguments for the fermionic counterpart, namely
Gross--Neveu-type models, we verify that such conclusions must also hold for
them, as recently suggested.Comment: 8 pages, final version to appear in Physics Letters B Revised
version, with misprints corrected and some references adde
On the entropy operator for the general SU(1,1) TFD formulation
In this letter, an entropy operator for the general unitary SU(1,1) TFD
formulation is proposed and used to lead a bosonic system from zero to finite
temperature. Namely, considering the closed bosonic string as the target
system, the entropy operator is used to construct the thermal vacuum. The
behaviour of such a state under the breve conjugation rules is analized and it
was shown that the breve conjugation does not affect thermal effects. From this
thermal vacuum the thermal energy, the entropy and the free energy of the
closed bosonic string are calculated and the apropriated thermal distribution
for the system is found after the free energy minimization.Comment: 13 pages, revtex4, minor typos corrected, references adde
Integrability and duality in two-dimensional QCD
We consider bosonized , and prove that after rewritting the theory in
terms of gauge invariant fields, there exists an integrability condition valid
for the quantum theory as well. Furthermore, performing a duality type
transformation we obtain an appropriate action for the description of the
strong coupling limit, which is still integrable. We also prove that the model
displays a complicated set of constraints, restricting the dynamics of part of
the theory, but which are necessary to maintain the positive metric Hilbert
space.Comment: 31 pages, plain tex prep. CERN-TH.7354/94, July 1994, with
corrections in the text and reference
Exact S matrices and extended supersymmetry
In this revised version we correct some mistakes, realizing the supersymmetry
algebra on the exact S matrix, taking into account several phase factros. We
study the constraint imposed by supersymmetry on the exact -matrix of
model, and compute a non-trivial phase factor in the
relation between the -matrix and one of the supersymmetry generators. We
discuss several features connected with the physical interpretation of the
result. The supersymmetry current is studied in such context as well, and we
find some operators appearing in the conservation equation of the supersymmetry
current that might be connected with such phase factors. The relation with the
literature on the subject is also discussed. hep-th/yymmnnnComment: 12 pages, plain tex, 1 figure in uuencoded file after the tex file,
prep CERN-TH-7106/9
A model displaying extremely inhomogeneous matter distribution in General Relativity
We consider a toy metric in four dimensional space-time defined in terms of a
recursive hierarchical prescription. The matter distribution turns out to be
extremely inhomogeneous. Surprisingly, for very large samples the average mass
density tends (very slowly) to a constant. There is no trace of fractal
dimension left.Comment: 7 pages, 3 figure
Operator solutions of two-dimensional chiral gauge theories
The exact operator solutions of two-dimensional anomaly-free chiral abelian
gauge theories are obtained. We show that anomaly-cancellation conditions arise
as consistency requirements of these solutions. For a certain class of flavour
symmetries, fermion condensates are constructed. These are shown to violate the
fermion-number conservation rule. The models are extended to include massive
fermions. We propose a bosonised lagrangian for the massive theory and verify
that it complies with the Gupta-Bleuler condition.Comment: 14 pages, latex fil
Loop scattering in two-dimensional QCD
Using the integrability conditions that we recently obtained in QCD with
massless fermions, we arrive at a sufficient number of conservation laws to be
able to fix the scattering amplitudes involving a local version of the Wilson
loop operator.Comment: 6 pages, plain tex
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