34 research outputs found
Cosmological Constant and Axions in String Theory
String theory axions appear to be promising candidates for explaining
cosmological constant via quintessence. In this paper, we study conditions on
the string compactifications under which axion quintessence can happen. For
sufficiently large number of axions, cosmological constant can be accounted for
as the potential energy of axions that have not yet relaxed to their minima. In
compactifications that incorporate unified models of particle physics, the
height of the axion potential can naturally fall close to the observed value of
cosmological constant.Comment: 22 page
On Nonperturbative Exactness of Konishi Anomaly and the Dijkgraaf-Vafa Conjecture
In this paper we study the nonperturbative corrections to the generalized
Konishi anomaly that come from the strong coupling dynamics of the gauge
theory. We consider U(N) gauge theory with adjoint and Sp(N) or SO(N) gauge
theory with symmetric or antisymmetric tensor. We study the algebra of chiral
rotations of the matter field and show that it does not receive nonperturbative
corrections. The algebra implies Wess-Zumino consistency conditions for the
generalized Konishi anomaly which are used to show that the anomaly does not
receive nonperturbative corrections for superpotentials of degree less than
2l+1 where 2l=3c(Adj)-c(R) is the one-loop beta function coefficient. The
superpotentials of higher degree can be nonperturbatively renormalized because
of the ambiguities in the UV completion of the gauge theory. We discuss the
implications for the Dijkgraaf-Vafa conjecture.Comment: 23 page
Chiral Rings, Vacua and Gaugino Condensation of Supersymmetric Gauge Theories
We find the complete chiral ring relations of the supersymmetric U(N) gauge
theories with matter in adjoint representation. We demonstrate exact
correspondence between the solutions of the chiral ring and the supersymmetric
vacua of the gauge theory. The chiral ring determines the expectation values of
chiral operators and the low energy gauge group. All the vacua have nonzero
gaugino condensation. We study the chiral ring relations obeyed by the gaugino
condensate. These relations are generalizations of the formula
of the pure gauge theory.Comment: 38 page
MHV Vertices And Tree Amplitudes In Gauge Theory
As an alternative to the usual Feynman graphs, tree amplitudes in Yang-Mills
theory can be constructed from tree graphs in which the vertices are tree level
MHV scattering amplitudes, continued off shell in a particular fashion. The
formalism leads to new and relatively simple formulas for many amplitudes, and
can be heuristically derived from twistor space.Comment: 27 p
Axions In String Theory
In the context of string theory, axions appear to provide the most plausible
solution of the strong CP problem. However, as has been known for a long time,
in many string-based models, the axion coupling parameter F_a is several orders
of magnitude higher than the standard cosmological bounds. We re-examine this
problem in a variety of models, showing that F_a is close to the GUT scale or
above in many models that have GUT-like phenomenology, as well as some that do
not. On the other hand, in some models with Standard Model gauge fields
supported on vanishing cycles, it is possible for F_a to be well below the GUT
scale.Comment: 62 pages, v2; references, acknowledgements and minor corrections
adde
Bounds on masses of bulk fields in string compactifications
In string compactification on a manifold X, in addition to the string scale
and the normal scales of low-energy particle physics, there is a Kaluza-Klein
scale 1/R associated with the size of X. We present an argument that generic
string models with low-energy supersymmetry have, after moduli stabilization,
bulk fields with masses which are parametrically lighter than 1/R. We discuss
the implications of these light states for anomaly mediation and gaugino
mediation scenarios.Comment: 15 page
Presentations from the annual meeting of the MIT/Industry Cooperative research Program.
Caption titleMay 199
Presentations from the MIT/Industry Cooperative Research Program : annual meeting, 1990
Statement of responsibility reads: Peter P. Belobaba; Catherine H. Bohutinsky; Anthony 0. Lee; Elizabeth L. Williamson; Amedeo R. Odoni, Stephan Kolitz and Mostafa Terrab; John Pararas; Robert W. Simpson; Tom Svrcek and Peter P. BelobabaJune 199