79 research outputs found
The Super-little Higgs
Supersymmetry combined with little-Higgs can render the Higgs vev
super-little, providing models of electroweak symmetry breaking free from
fine-tunings. We discuss the difficulties that arise in implementing this idea
and propose one simple successful model. Thanks to appropriately chosen Higgs
representations, D-terms give no tree-level mass term to the Goldstone. The
fermion representations are anomaly free, generation independent and embeddable
into an SU(6) GUT. A simple mechanism provides the large top quark mass.Comment: Additional mechanism to get a quartic coupling discussed. References
adde
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
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
Brane Boxes: Bending and Beta Functions
We study the type IIB brane box configurations recently introduced by Hanany
and Zaffaroni. We show that even at finite string coupling, one can construct
smooth configurations of branes with fairly arbitrary gauge and flavor
structure. Limiting our attention to the better understood case where NS-branes
do not intersect over a four dimensional surface gives some restrictions on the
theories, but still permits many examples, both anomalous and non-anomalous. We
give several explicit examples of such configurations and discuss what
constraints can be imposed on brane-box theories from bending considerations.
We also discuss the relation between brane bending and beta-functions for
brane-box configurations.Comment: latex, 18 pages, 8 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
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
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
Composite Quarks and Leptons from Dynamical Supersymmetry Breaking without Messengers
We present new theories of dynamical SUSY breaking in which the strong
interactions that break SUSY also give rise to composite quarks and leptons
with naturally small Yukawa couplings. In these models, SUSY breaking is
communicated directly to the composite fields without ``messenger''
interactions. The compositeness scale can be anywhere between 10 TeV and the
Planck scale. These models can naturally solve the supersymmetric flavor
problem, and generically predict sfermion mass unification independent from
gauge unification.Comment: 27 pages, LaTeX; Clarified flavor symmetry of strong interactions;
corrected overestimate of FCNC's; conclusions strengthene
Constraints on Astro-unparticle Physics from SN 1987A
SN 1987A observations have been used to place constraints on the interactions
between standard model particles and unparticles. In this study we calculate
the energy loss from the supernovae core through scalar, pseudo scalar, vector,
pseudo vector unparticle emission from nuclear bremsstrahlung for degenerate
nuclear matter interacting through one pion exchange. In order to examine the
constraints on we considered the emission of scalar, pseudo
scalar, vector, pseudo vector and tensor through the pair annihilation process
. In addition we have re-examined other pair
annihilation processes. The most stringent bounds on the dimensionless coupling
constants for and are obtained from
nuclear bremsstrahlung process for the pseudo scalar and pseudo-vector
couplings and for
tensor interaction, the best limit on dimensionless coupling is obtained from
and we get .Comment: 12 pages, 2 postscript figure
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
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