88 research outputs found
A Solution to the Problem in Gauge-mediated Supersymmetry-breaking Models
We point out that a sector required to set the cosmological constant to zero
in gauge-mediated supersymmetry-breaking models naturally produces a
supersymmetry-invariant mass ( term) for Higgs doublets of the order of
the electroweak scale. Since this new sector preserves the supersymmetry, it
does not generate supersymmetry-breaking masses for the Higgs doublets and thus
the problem is solved.Comment: Latex fil
Electroweak Symmetry Breaking From Monopole Condensation
We examine models where massless chiral fermions with both "electric" and
"magnetic" hypercharges could form condensates. When some of the fermions are
also electroweak doublets such condensates can break the electroweak gauge
symmetry down to electromagnetism in the correct way. Since ordinary
hypercharge is weakly coupled at the TeV scale, magnetic hypercharge is
strongly coupled and can potentially drive the condensation. Such models are
similar to technicolor, but with hypercharge playing the role of the
technicolor gauge group, so the standard model gauge group breaks itself. A
heavy top mass can be generated via the Rubakov-Callan effect and could thus
decouple the scale of flavor physics from the electroweak scale.Comment: Absence of pseudo-Goldstone bosons explain, discussion of the role of
flavor physics clarified, other minor changes. References adde
The strength of small-instanton amplitudes in gauge theories with compact extra dimensions
We study instanton effects in theories with compact extra dimensions. We
perform an instanton calculation in a 5d theory on a circle of radius R, with
gauge, scalar, and fermion fields in the bulk of the extra dimension. We show
that, depending on the matter content, instantons of size rho << R can dominate
the amplitude. Using deconstruction as an ultraviolet definition of the theory
allows us to show, in a controlled approximation, that for a small number of
bulk fermions, the amplitude for small size instantons exponentially grows as
e^{O(1)R/rho}.Comment: Title modified, references added, typos corrected. Version to appear
in JHEP. 24 pages, 1 figur
Supersymmetry Breaking Triggered by Monopoles
We investigate N = 1 supersymmetric gauge theories where monopole
condensation triggers supersymmetry breaking in a metastable vacuum. The
low-energy effective theory is an O'Raifeartaigh-like model of the kind
investigated recently by Shih where the R-symmetry can be spontaneously broken.
We examine several implementations with varying degrees of phenomenological
interest.Comment: 20 pages, 4 figures (v2: minor clarifications and typos fixed
Visible Effects of the Hidden Sector
The renormalization of operators responsible for soft supersymmetry breaking
is usually calculated by starting at some high scale and including only visible
sector interactions in the evolution equations, while ignoring hidden sector
interactions. Here we explain why this is correct only for the most trivial
structures in the hidden sector, and discuss possible implications. This
investigation was prompted by the idea of conformal sequestering. In that
framework hidden sector renormalizations by nearly conformal dynamics are
critical. In the original models of conformal sequestering it was necessary to
impose hidden sector flavor symmetries to achieve the sequestered form. We
present models which can evade this requirement and lead to no-scale or anomaly
mediated boundary conditions; but the necessary structures do not seem generic.
More generally, the ratios of scalar masses to gaugino masses, the -term,
the -term, -terms, and the gravitino mass can be significantly
affected.Comment: 23 pages, no figure
Some Explorations in Holomorphy
In supersymmetric theories, one can obtain striking results and insights by
exploiting the fact that the superpotential and the gauge coupling function are
holomorphic functions of the model parameters. The precise meaning of this
holomorphy is subtle, and has been explained most clearly by Shifman and
Vainshtein, who have stressed the role of the Wilsonian effective action. In
this note, we elaborate on the Shifman-Vainshtein program, applying it to
examples in grand unification, supersymmetric QCD and string theory. We stress
that among the ``model parameters" are the cutoffs used to define the Wilsonian
action itself, and that generically these must be defined in a field-dependent
manner to obtain holomorphic results.Comment: (26 pages and 2 figures as one uuencoded PostScript file) SCIPP
94/11. Important references added; typos correcte
Remarks on the Racetrack Scheme
There are only a small number of ideas for stabilizing the moduli of string
theory. One of the most appealing of these is the racetrack mechanism, in which
a delicate interplay between two strongly interacting gauge groups fixes the
value of the coupling constant. In this note, we explore this scenario. We find
that quite generally, some number of discrete tunings are required in order
that the mechanism yield a small gauge coupling. Even then, there is no sense
in which a weak coupling approximation is valid. On the other hand, certain
holomorphic quantities can be computed, so such a scheme is in principle
predictive. Searching for models which realize this mechanism is thus of great
interest. We also remark on cosmology in these schemes.Comment: 20 pp, latex, discussion of calculability modifie
Search for Nanosecond Near-infrared Transients around 1280 Celestial Objects
Stars and planetary system
The GUT Scale and Superpartner Masses from Anomaly Mediated Supersymmetry Breaking
We consider models of anomaly-mediated supersymmetry breaking (AMSB) in which
the grand unification (GUT) scale is determined by the vacuum expectation value
of a chiral superfield. If the anomaly-mediated contributions to the potential
are balanced by gravitational-strength interactions, we find a
model-independent prediction for the GUT scale of order . The GUT threshold also affects superpartner masses, and can easily
give rise to realistic predictions if the GUT gauge group is asymptotically
free. We give an explicit example of a model with these features, in which the
doublet-triplet splitting problem is solved. The resulting superpartner
spectrum is very different from that of previously considered AMSB models, with
gaugino masses typically unifying at the GUT scale.Comment: 17 page
Duality between simple-group gauge theories and some applications
In this paper we investigate N=1 supersymmetric gauge theories with a product
gauge group. By using smoothly confining dynamics, we can find new dualities
which include higher-rank tensor fields, and in which the dual gauge group is
simple, not a product. Some of them are dualities between chiral and non-chiral
gauge theories. We also discuss some applications to dynamical supersymmetry
breaking phenomena and new confining theories with a tree-level superpotential.Comment: 33 pages, LaTeX, references added, version to appear in PR
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