557 research outputs found
Dirac Gauginos: A User Manual
The issue of a Majorana, Dirac or pseudo-Dirac mass for gauginos must not be
reduced to a question of an extension of the Minimal Supersymmetric Standard
Model by extra states, parameters and phenomenological implications. On the
contrary, it is intimately related to the fundamental issue of the realization
of new symmetries in nature, R-symmetries. We present here a very dense
compilation of the main features of models with (pseudo-)Dirac gauginos.Comment: 4 pages, no figure. References adde
A Note on New Sources of Gaugino Masses
In IIB orientifold models, the singlet twisted moduli appear in the
tree-level gauge kinetic function. They might be responsible for generating
gaugino masses if they acquire non-vanishing F-terms. We discuss some aspects
of this new possibility, such as the size of gaugino masses and their
non-universalities. A possible brane setting is presented to illustrate the
usefulness of these new sources.Comment: 7 pages, late
(Pseudo)goldstinos, SUSY fluids, Dirac gravitino and gauginos
We review the emergence and fate of goldstinos in different frameworks.
First, we consider a super-Higgs mechanism when supersymmetry breaking is
induced by neither an F-term nor a D-term but related to a more general stress
energy-momentum tensor. This allows us to build a novel Lagrangian that
describes the propagation of a spin-3/2 state in a fluid. Then we briefly
review the ubiquitous pseudo-goldstinos when breaking supersymmetry in an extra
dimension. We remind that the fermion (gravitino or gaugino) soft masses can be
tuned to be of Dirac-type. Finally, we briefly connect the latter to the study
of models with Dirac-type gaugino masses and stress the advantage of having
both an F and a D-term sizable contributions for the hierarchies of soft-terms
as well as for minimizing R-symmetry breaking.Comment: 21 page
Scales and Cosmological Applications of M Theory
I review recent results in three topics of the M-world: (i) Scales. (ii) New
dark matter candidates. (iii) Cosmological solutions from p-branes. The three
topics are discussed in the framework of Ho\v{r}ava-Witten compactifications.
Part (iii) includes comments on cosmological solutions in M-theory describing
nucleation of universes through instanton effects and expansions toward
asymptotically flat or anti-de-Sitter spaces.Comment: 19 pages, latex, uses sprocl.st
Disordered Extra Dimensions
A very large extra dimension may contain many localized branes. We discuss
the possibility to formulate such models as a spin system where each spin
indicates the supersymmetry direction preserved by the corresponding brane. In
the evolution of the universe, the extra dimensions might have ended into a
vacuum made of patches with different orientation of the spins, responsible for
the observed breaking of supersymmetry. We discuss the limit where the
separation of these patches is by very thin defects described as localization
of gravitino masses.Comment: 15 pages, no figure. Typos corrected. References added. Version
accepted for publication
Limits on the Size of Extra Dimensions and the String Scale
We give a brief summary of present bounds on the size of possible
extra-dimensions as well as the string scale from collider experiments.Comment: 11 pages, 4 figures, uses lathuile.sty . Talks given by I.A. at La
Thuile2001 and by K.B. at Moriond200
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