231 research outputs found
Tree level spontaneous R-symmetry breaking in O'Raifeartaigh models
We show that in O'Raifeartaigh models of spontaneous supersymmetry breaking,
R-symmetries can be broken by non-zero values of fields at tree level, rather
than by vacuum expectation values of pseudomoduli at loop level. As a
complement of the recent result by Shih, we show that there must be a field in
the theory with R-charge different from zero and two in order for R-symmetry
breaking to occur, no matter whether the breaking happens at tree or loop
level. We review the example by CDFM, and construct two types of tree level
R-symmetry breaking models with a wide range of parameters and free of runaway
problem. And the R-symmetry is broken everywhere on the pseudomoduli space in
these models. This provides a rich set of candidates for SUSY model building
and phenomenology.Comment: 8 pages; v2: major revision to section 6; v3: minor revision and
typos; v4: typos, published version; v5: fix Latex syntax error, published
versio
Exploring General Gauge Mediation
We explore various aspects of General Gauge Mediation(GGM). We present a
reformulation of the correlation functions used in GGM, and further elucidate
their IR and UV properties. Additionally we clarify the issue of UV sensitivity
in the calculation of the soft masses in the MSSM, highlighting the role of the
supertrace over the messenger spectrum. Finally, we present weakly coupled
messenger models which fully cover the parameter space of GGM. These examples
demonstrate that the full parameter space of GGM is physical and realizable.
Thus it should be considered a valid basis for future phenomenological
explorations of gauge mediation.Comment: 27 pages, minor changes, typos fixed in appendix
Proposal for Higgs and Superpartner Searches at the LHCb Experiment
The spectrum of supersymmetric theories with R-parity violation are much more
weakly constrained than that of supersymmetric theories with a stable
neutralino. We investigate the signatures of supersymmetry at the LHCb
experiment in the region of parameter space where the neutralino decay leaves a
displaced vertex. We find sensitivity to squark production up to squark masses
of order 1 TeV. We note that if the Higgs decays to neutralinos in this
scenario, LHCb should see the lightest Higgs boson before ATLAS and CMS.Comment: 7 pages, 5 figure
David Getches: A Tribute to a Leader and a Scholar
Article published in the Federal Law
Semi-Direct Gauge Mediation with the 4-1 Model
We analyze a model of Semi-Direct Gauge Mediation in which the hidden sector
is the 4-1 model and the messenger fields are charged under the U(1) gauge
group. At tree level, the SUSY-breaking F-terms induce D-terms from which
SUSY-split messenger masses arise. We calculate these masses by three
complementary methods. Additionally, we compute the one-loop corrections to the
masses. We consider this model both with and without a Fayet-Iliopoulos term
for the hidden sector U(1). Finally, we write down a simple model of Minimal
Gauge Mediation in which the only scale is dynamically generated.Comment: 29 pages, 5 figures, harvma
Embedding the Pentagon
The Pentagon Model is an explicit supersymmetric extension of the Standard
Model, which involves a new strongly-interacting SU(5) gauge theory at
TeV-scale energies. We show that the Pentagon can be embedded into an SU(5) x
SU(5) x SU(5) gauge group at the GUT scale. The doublet-triplet splitting
problem, and proton decay compatible with experimental bounds, can be
successfully addressed in this context. The simplest approach fails to provide
masses for the lighter two generations of quarks and leptons; however, this
problem can be solved by the addition of a pair of antisymmetric tensor fields
and an axion.Comment: 39 page
QCD Corrections to K-Kbar Mixing in R-symmetric Supersymmetric Models
The leading-log QCD corrections to K-Kbar mixing in R-symmetric
supersymmetric models are computed using effective field theory techniques. The
spectrum topology where the gluino is significantly heavier than the squarks is
motivated and focused on. It is found that, like in the MSSM, QCD corrections
can tighten the kaon mass difference bound by roughly a factor of three. CP
violation is also briefly considered, where QCD corrections can constrain
phases to be as much as a factor of ten smaller than the uncorrected value.Comment: 11 pages, 11 pdf-figures; updated acknowledgments and references,
clarified relationship to Ref[17], clarified CP-violation sectio
Generalized messenger sector for gauge mediation of supersymmetry breaking and the soft spectrum
We consider a generic renormalizable and gauge invariant messenger sector and
derive the sparticle mass spectrum using the formalism introduced for General
Gauge Mediation. Our results recover many expressions found in the literature
in various limits. Constraining the messenger sector with a global symmetry
under which the spurion field is charged, we analyze Extraordinary Gauge
Mediation beyond the small SUSY breaking limit. Finally, we include D-term
contributions and compute their corrections to the soft masses. This leads to a
perturbative framework allowing to explore models capable of fully covering the
parameter space of General Gauge Mediation to the Supersymmetric Standard
Model.Comment: Minor changes to clarify notation. Requirement of global symmetry is
relaxed in the derivation of scalar masses in the small SUSY breaking limi
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