A Solution to the μ\mu 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 ($\mu$ 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 $\mu$ 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 $\mu$-term, the $B\mu$-term, $A$-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 $M_{\rm Planck} / (16\pi^2)$. 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