8 research outputs found
Gaugino condensation in 4-D superstring models
We study the possibility that supersymmetry is broken via a gaugino
condensate in four dimensional string theories. We derive an effective
low-energy theory describing the Goldstone mode associated with the R-symmetry
breaking driven by gaugino condensation and show that this gives a description
of gaugino condensation equivalent, at tree level, to other effective
Lagrangian approaches based on the symmetries of the theory. A study of the
mass gap equation shows that non-perturbative effects favour the appearance of
a gaugino condensate. By minimizing the effective potential describing both the
condensate and the moduli determining the gauge coupling constant and radius of
compactification we show that large hierarchy may occur between the gravitino
mass and the Planck mass with the existence of only one gaugino condensate.
Associated with this is a determination of the fine structure constant and the
compactification scale.Comment: 19 pages, report OUTP-92-14
Entropic C-theorems in free and interacting two-dimensional field theories
The relative entropy in two-dimensional field theory is studied on a cylinder
geometry, interpreted as finite-temperature field theory. The width of the
cylinder provides an infrared scale that allows us to define a dimensionless
relative entropy analogous to Zamolodchikov's function. The one-dimensional
quantum thermodynamic entropy gives rise to another monotonic dimensionless
quantity. I illustrate these monotonicity theorems with examples ranging from
free field theories to interacting models soluble with the thermodynamic Bethe
ansatz. Both dimensionless entropies are explicitly shown to be monotonic in
the examples that we analyze.Comment: 34 pages, 3 figures (8 EPS files), Latex2e file, continuation of
hep-th/9710241; rigorous analysis of sufficient conditions for universality
of the dimensionless relative entropy, more detailed discussion of the
relation with Zamolodchikov's theorem, references added; to appear in Phys.
Rev.
Ginzburg-Landau functional for nearly antiferromagnetic perfect and disordered Kondo lattices
Interplay between Kondo effect and trends to antiferromagnetic and spin glass
ordering in perfect and disordered bipartite Kondo lattices is considered.
Ginzburg-Landau equation is derived from the microscopic effective action
written in three mode representation (Kondo screening, antiferromagnetic
correlations and spin liquid correlations). The problem of local constraint is
resolved by means of Popov-Fedotov representation for localized spin operators.
It is shown that the Kondo screening enhances the trend to a spin liquid
crossover and suppresses antiferromagnetic ordering in perfect Kondo lattices
and spin glass ordering in doped Kondo lattices. The modified Doniach's diagram
is constructed, and possibilities of going beyond the mean field approximation
are discussed.Comment: 18 pages, RevTeX, 7 EPS figures include
Baryogenesis in Models with a Low Quantum Gravity Scale
We make generic remarks about baryogenesis in models where the scale of
quantum gravity is much below the Planck scale. These correspond to M-theory
vacua with a large volume for the internal space. Baryogenesis is a challenge,
particularly for M_s \lappeq 10^5 GeV, because there is an upper bound on the
reheat temperature of the Universe, and because certain baryon number violating
operators must be suppressed. We discuss these constraints for different values
of , and illustrate with a toy model the possibility of using horizontal
family symmetries to circumvent them.Comment: 15 pages, latex, one figure. References adde