2,319 research outputs found
A Comparison of Supersymmetry Breaking and Mediation Mechanisms
We give a unified treatment of different models of supersymmetry breaking and
mediation from a four dimensional effective field theory standpoint. In
particular a comparison between GMSB and various gravity mediated versions of
SUSY breaking shows that, once the former is embedded within a SUGRA framework,
there is no particular advantage to that mechanism from the point of view of
FCNC suppression. We point out the difficulties of all these scenarios - in
particular the cosmological modulus problem. We end with a discussion of
possible string theory realizations.Comment: Added clarifications and references, 20 page
The sparticle spectrum in Minimal gaugino-Gauge Mediation
We compute the sparticle mass spectrum in the minimal four-dimensional
construction that interpolates between gaugino mediation and ordinary gauge
mediation.Comment: 21 pages, 9 figures; V2: refs. added; V3: some typos correcte
Superpartner spectrum of minimal gaugino-gauge mediation
We evaluate the sparticle mass spectrum in the minimal four-dimensional
construction that interpolates between gaugino and ordinary gauge mediation at
the weak scale. We find that even in the hybrid case -- when the messenger
scale is comparable to the mass of the additional gauge particles -- both the
right-handed as well as the left-handed sleptons are lighter than the bino in
the low-scale mediation regime. This implies a chain of lepton production and,
consequently, striking signatures that may be probed at the LHC already in the
near future.Comment: 8 pages, 3 figures; V2: refs and a few comments added; V3 title
change
Asymmetric Origin for Gravitino Relic Density in the Hybrid Gravity-Gauge Mediated Supersymmetry Breaking
We propose the hybrid gravity-gauge mediated supersymmetry breaking where the
gravitino mass is about several GeV. The strong constraints on supersymmetry
viable parameter space from the CMS and ATLAS experiments at the LHC can be
relaxed due to the heavy colored supersymmetric particles, and it is consistent
with null results in the dark matter (DM) direct search experiments such as
XENON100. In particular, the possible maximal flavor and CP violations from the
relatively small gravity mediation may naturally account for the recent LHCb
anomaly. In addition, because the gravitino mass is around the asymmetric DM
mass, we propose the asymmetric origin of the gravitino relic density and solve
the cosmological coincident problem on the DM and baryon densities \Omega_{\rm
DM}:\Omega_{B}\approx 5:1. The gravitino relic density arises from asymmetric
metastable particle (AMP) late decay. However, we show that there is no AMP
candidate in the minimal supersymmetric Standard Model (SM) due to the robust
gaugino/Higgsino mediated wash-out effects. Interestingly, AMP can be realized
in the well motivated supersymmetric SMs with vector-like particles or
continuous U(1)_R symmetry. Especially, the lightest CP-even Higgs boson mass
can be lifted in the supersymmetric SMs with vector-like particles.Comment: RevTex4, 21 pages, 1 figure, minor corrections, JHEP versio
Combining Anomaly and Z' Mediation of Supersymmetry Breaking
We propose a scenario in which the supersymmetry breaking effect mediated by
an additional U(1)' is comparable with that of anomaly mediation. We argue that
such a scenario can be naturally realized in a large class of models. Combining
anomaly with Z' mediation allows us to solve the tachyonic slepton problem of
the former and avoid significant fine tuning in the latter. We focus on an
NMSSM-like scenario where U(1)' gauge invariance is used to forbid a tree-level
mu term, and present concrete models, which admit successful dynamical
electroweak symmetry breaking. Gaugino masses are somewhat lighter than the
scalar masses, and the third generation squarks are lighter than the first two.
In the specific class of models under consideration, the gluino is light since
it only receives a contribution from 2-loop anomaly mediation, and it decays
dominantly into third generation quarks. Gluino production leads to distinct
LHC signals and prospects of early discovery. In addition, there is a
relatively light Z', with mass in the range of several TeV. Discovering and
studying its properties can reveal important clues about the underlying model.Comment: Minor changes: references added, typos corrected, journal versio
Tame D-tadpoles in gauge mediation
We revisit models of gauge mediated supersymmetry breaking where messenger
parity is violated. Such a symmetry is usually invoked in order to set to zero
potentially dangerous hypercharge D-term tadpoles. A milder hypothesis is that
the D-tadpole vanishes only at the first order in the gauge coupling constant.
Then the next order leads to a contribution to the sfermion masses which is of
the same magnitude as the usual radiative one. This enlarges the parameter
space of gauge mediated models. We first give a completely general
characterization of this contribution, in terms of particular three-point
functions of hidden sector current multiplet operators. We then explore the
parameter space by means of two simple weakly coupled models, where the
D-tadpole arising at two-loops has actually a mild logarithmic divergence.Comment: 13 pages + 9 pages of appendix, 1 figure; v2: some clarifying
comments added, version to appear in JHE
Gaugino Anomaly Mediated SUSY Breaking: phenomenology and prospects for the LHC
We examine the supersymmetry phenomenology of a novel scenario of
supersymmetry (SUSY) breaking which we call Gaugino Anomaly Mediation, or
inoAMSB. This is suggested by recent work on the phenomenology of flux
compactified type IIB string theory. The essential features of this scenario
are that the gaugino masses are of the anomaly-mediated SUSY breaking (AMSB)
form, while scalar and trilinear soft SUSY breaking terms are highly
suppressed. Renormalization group effects yield an allowable sparticle mass
spectrum, while at the same time avoiding charged LSPs; the latter are common
in models with negligible soft scalar masses, such as no-scale or gaugino
mediation models. Since scalar and trilinear soft terms are highly suppressed,
the SUSY induced flavor and CP-violating processes are also suppressed. The
lightest SUSY particle is the neutral wino, while the heaviest is the gluino.
In this model, there should be a strong multi-jet +etmiss signal from squark
pair production at the LHC. We find a 100 fb^{-1} reach of LHC out to
m_{3/2}\sim 118 TeV, corresponding to a gluino mass of \sim 2.6 TeV. A double
mass edge from the opposite-sign/same flavor dilepton invariant mass
distribution should be visible at LHC; this, along with the presence of short--
but visible-- highly ionizing tracks from quasi-stable charginos, should
provide a smoking gun signature for inoAMSB.Comment: 30 pages including 14 .eps figure
Allelic variation in the TNF-beta gene does not explain the low TNF-beta response in patients with primary biliary cirrhosis
Evaluation of diversity among common beans (Phaseolus vulgaris L.) from two centers of domestication using 'omics' technologies
<p>Abstract</p> <p>Background</p> <p>Genetic diversity among wild accessions and cultivars of common bean (<it>Phaseolus vulgaris </it>L.) has been characterized using plant morphology, seed protein allozymes, random amplified polymorphic DNA, restriction fragment length polymorphisms, DNA sequence analysis, chloroplast DNA, and microsatellite markers. Yet, little is known about whether these traits, which distinguish among genetically distinct types of common bean, can be evaluated using omics technologies.</p> <p>Results</p> <p>Three 'omics' approaches: transcriptomics, proteomics, and metabolomics were used to qualitatively evaluate the diversity of common bean from two Centers of Domestication (COD). All three approaches were able to classify common bean according to their COD using unsupervised analyses; these findings are consistent with the hypothesis that differences exist in gene transcription, protein expression, and synthesis and metabolism of small molecules among common bean cultivars representative of different COD. Metabolomic analyses of multiple cultivars within two common bean gene pools revealed cultivar differences in small molecules that were of sufficient magnitude to allow identification of unique cultivar fingerprints.</p> <p>Conclusions</p> <p>Given the high-throughput and low cost of each of these 'omics' platforms, significant opportunities exist for their use in the rapid identification of traits of agronomic and nutritional importance as well as to characterize genetic diversity.</p
Flavor of quiver-like realizations of effective supersymmetry
We present a class of supersymmetric models which address the flavor puzzle
and have an inverted hierarchy of sfermions. Their construction involves
quiver-like models with link fields in generic representations. The magnitude
of Standard-Model parameters is obtained naturally and a relatively heavy Higgs
boson is allowed without fine tuning. Collider signatures of such models are
possibly within the reach of LHC in the near future.Comment: LaTeX, 17 pages, 3 figures. V2: reference adde
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