1,074 research outputs found
The Role of Scalar and Pseudoscalar Fields in Determining Nucleosynthesis Bounds on the Scale of Supersymmetry Breaking
The effect of spin-0 goldstino superpartners is considered on the
nucleosynthesis bounds arising when a superlight gravitino appears as an
effective massless neutrino species. When the scalar and pseudoscalar
superpartners are relativistic they will decouple at much later times than the
goldstino and consequently will be the dominant effect when obtaining a
nucleosynthesis bound on the scale of supersymmetry breaking. Assuming that the
scalar and pseudoscalar fields decouple at a temperature no later than O(100)
MeV, then typically the scale of supersymmetry breaking \sqrt{F} > 60 TeV. This
corresponds to a lower bound on the gravitino mass m_{3/2} > 1 eV.Comment: 12 pages, 1 figure; Version to be published in Phys. Lett.
Superlight gravitinos in electron-photon collisions
Motivated by recent studies of supersymmetry in higher-dimensional spaces, we
discuss the experimental signatures of a superlight gravitino, mass < 0.001 eV.
We concentrate on the process (e- gamma -> selectronR gravitino) as a probe of
supersymmetry, where a single heavy superpartner and a superlight gravitino are
produced. The fact that there is only one heavy superpartner in the final state
in this process would require a lower center-of-mass energy for on-shell
production compared to conventional pair production. For instance, for a 500
GeV machine, we find that a positive signal will be found if the supersymmetry
breaking scale is less than about 2 TeV. If no positive signal is found, this
process puts a bound on the supersymmetry breaking scale.Comment: 8 pages Added 2 terms to eqn(3) for easy reference and other minor
changes to improve clarit
A Soft-Wall Dilaton
We study the properties of the dilaton in a soft-wall background using two
solutions of the Einstein equations. These solutions contain an asymptotically
AdS metric with a nontrivial scalar profile that causes both the spontaneous
breaking of conformal invariance and the generation of a mass gap in the
particle spectrum. We first present an analytic solution, using the
superpotential method, that describes a CFT spontaneously broken by a finite
dimensional operator in which a light dilaton mode appears in the spectrum.
This represents a tuning in the vanishing of the quartic coupling in the
effective potential that could be naturally realised from an underlying
supersymmetry. Instead, by considering a generalised analytic scalar bulk
potential that quickly transitions at the condensate scale from a walking
coupling in the UV to an order-one -function in the IR, we obtain a
naturally light dilaton. This provides a simple example for obtaining a
naturally light dilaton from nearly-marginal CFT deformations in the more
realistic case of a soft-wall background.Comment: 23 pages, 8 figures; v2: version published in JHE
Three generations on a local vortex in extra dimensions
We develop an approach to the origin of three generations of the Standard
Model fermions from one generation in a higher-dimensional theory, where
four-dimensional fermions appear as zero modes trapped in the core of a
topological defect, and the hierarchy of masses and mixings is produced by wave
function overlaps in extra dimensions. We present a model with unbroken U(1)
symmetry where three zero modes appear on an Abrikosov-Nielsen-Olesen vortex
due to nontrivial scalar--fermion interactions.Comment: 8 pages, no figure
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