180 research outputs found
Spectrum of TeV Particles in Warped Supersymmetric Grand Unification
In warped supersymmetric grand unification, XY gauge particles appear near
the TeV scale along with Kaluza-Klein towers of the standard model gauge
fields. In spite of this exotic low-energy physics, MSSM gauge coupling
unification is preserved and proton decay is naturally suppressed. In this
paper we study in detail the low-lying mass spectrum of superparticles and GUT
particles in this theory, taking supersymmetry breaking to be localized to the
TeV brane. The masses of the MSSM particles, Kaluza-Klein modes, and XY states
are all determined by two parameters, one which fixes the strength of the
supersymmetry breaking and the other which sets the scale of the infrared
brane. A particularly interesting result is that for relatively strong
supersymmetry breaking, the XY gauginos and the lowest Kaluza-Klein excitations
of the MSSM gauginos may both lie within reach of the LHC, providing the
possibility that the underlying unified gauge symmetry and the enhanced N=2
supersymmetry of the theory will both be revealed.Comment: 29 pages, 5 figure
Stress coping style does not determine social status, but influences the consequences of social subordination stress
Chronic stress exposure may have negative consequences for health. One of the most common sources of chronic stress is stress associated with social interaction. In rodents, the effects of social stress can be studied in a naturalistic way using the visual burrow system (VBS). The way an individual copes with stress, their “stress coping style”, may influence the consequences of social stress. In the current study we tested the hypothesis that stress coping style may modulate social status and influence the consequences of having a lower social status. We formed 7 VBS colonies, with 1 proactive coping male, 1 passive coping male, and 4 female rats per colony to assess whether a rat's coping style prior to colony formation could predict whether that individual is more likely to become socially dominant. The rats remained in their respective colonies for 14 days and the physiological and behavioral consequences of social stress were assessed. Our study shows that stress coping style does not predict social status. However, stress coping style may influence the consequences of having a lower social status. Subordinate passive and proactive rats had distinctly different wound patterns; proactive rats had more wounds on the front of their bodies. Behavioral analysis confirmed that proactive subordinate rats engaged in more offensive interactions. Furthermore, subordinate rats with a proactive stress coping style had larger adrenals, and increased stress responsivity to a novel acute stressor (restraint stress) compared to passive subordinate rats or dominant rats, suggesting that the allostatic load may have been larger in this group
Warped Supersymmetric Grand Unification
We construct a realistic theory of grand unification in AdS_5 truncated by
branes, in which the unified gauge symmetry is broken by boundary conditions
and the electroweak scale is generated by the AdS warp factor. We show that the
theory preserves the successful gauge coupling unification of the 4D MSSM at
leading-logarithmic level. Kaluza-Klein (KK) towers, including those of XY
gauge and colored Higgs multiplets, appear at the TeV scale, while the extra
dimension provides natural mechanisms for doublet-triplet splitting and proton
decay suppression. In one possible scenario supersymmetry is strongly broken on
the TeV brane, in which case the lightest SU(3)_C x SU(2)_L x U(1)_Y gauginos
are approximately Dirac and the mass of the lightest XY gaugino is pushed well
below that of the lowest gauge boson KK mode, improving the prospects for its
production at the LHC. The bulk Lagrangian possesses a symmetry that we call
GUT parity. If GUT parity is exact, the lightest GUT particle, most likely an
XY gaugino, is stable. Once produced in a collider, the XY gaugino hadronizes
to form mesons, some of which will be charged and visible as highly ionizing
tracks. The lightest supersymmetric particle is the gravitino of mass \sim
10^{-3} eV, which is also stable if R parity is conserved.Comment: 41 pages, LaTeX, version to appear in Phys. Rev.
Winding number and non-BPS bound states of walls in nonlinear sigma models
Non-supersymmetric multi-wall configurations are generically unstable. It is
proposed that the stabilization in compact space can be achieved by introducing
a winding number into the model. A BPS-like bound is studied for the energy of
configuration with nonvanishing winding number. Winding number is implemented
in an supersymmetric nonlinear sigma model with two chiral scalar
fields and a bound states of BPS and anti-BPS walls is found to exist in
noncompact spaces. Even in compactified space , this nontrivial bound
state persists above a critical radius of the compact dimension.Comment: 20pages, 14 figures, minor misprint corrections, figures added,
explanation of winding number adde
Hadronic production of light color-triplet Higgs bosons: an alternative signature for GUT
The conventional signature for grand unified theories (GUT) is the proton
decay. Recently, some models in extra dimensions or with specific discrete
symmetries, which aim at solving the doublet-triplet problem, allow the
color-triplet in the TeV mass region by suppressing the Yukawa couplings of the
triplets to matter fermions. We study the hadronic production and detection of
these TeV colored Higgs bosons as an alternative signature for GUT, which would
behave like massive stable charged particles in particle detectors producing a
striking signature of a charged track in the central tracking system and being
ionized in the outer muon chamber. We found that the LHC is sensitive to a
colored Higgs boson up to about 1.5 TeV. If the color-triplets are stable in
cosmological time scale, they may constitute an interesting fraction of the
dark matter.Comment: We added the description of a model by Goldberger et al.-- a 5D SU(5)
SUSY model in a slice of AdS space with special boundary conditions to
suppress proton decay. The color-triplet also has a TeV mas
Massive Hyper-Kahler Sigma Models and BPS Domain Walls
With the non-Abelian Hyper-Kahler quotient by U(M) and SU(M) gauge groups, we
give the massive Hyper-Kahler sigma models that are not toric in the N=1
superfield formalism. The U(M) quotient gives N!/[M! (N-M)!] (N is a number of
flavors) discrete vacua that may allow various types of domain walls, whereas
the SU(M) quotient gives no discrete vacua. We derive BPS domain wall solution
in the case of N=2 and M=1 in the U(M) quotient model.Comment: 16 pages, 1 figure, contribution to the Proceedings of the
International Conference on "Symmetry Methods in Physics (SYM-PHYS10)" held
at Yerevan, Armenia, 13-19 Aug. 200
Unification in 5D SO(10)
Gauge unification in a five dimensional supersymmetric SO(10) model
compactified on an orbifold is studied. One
orbifolding reduces N=2 supersymmetry to N=1, and the other breaks SO(10) to
the Pati-Salam gauge group \ps. Further breaking to the standard model gauge
group is made through the Higgs mechanism on one of the branes. The differences
of the three gauge couplings run logarithmically even in five dimensions and we
can keep the predictability for unification as in four dimensional gauge
theories. We obtain an excellent prediction for gauge coupling unification with
a cutoff scale GeV and a compactification scale
GeV. Finally, although proton decay due to
dimension 5 operators may be completely eliminated, the proton decay rate in
these models is sensitive to the placement of matter multiplets in the 5th
dimension, as well as to the unknown physics above the cutoff scale.Comment: 33 pages, one reference added and fig. 3 caption correcte
Susceptibility or resilience? Prenatal stress predisposes male rats to social subordination, but facilitates adaptation to subordinate status
Mood disorders such as major depressive disorder (MDD) affect a significant proportion of the population. Although progress has been made in the development of therapeutics, a large number of individuals do not attain full remission of symptoms and adverse side effects affect treatment compliance for some. In order to develop new therapies, there is a push for new models that better reflect the multiple risk factors that likely contribute to the development of depressive illness. We hypothesized that early life stress would exacerbate the depressive-like phenotype that we have previously observed in socially subordinate (SUB) adult male rats in the visible burrow system (VBS), a semi-natural, ethologically relevant environment in which males in a colony form a dominance hierarchy. Dams were exposed to chronic variable stress (CVS) during the last week of gestation, resulting in a robust and non-habituating glucocorticoid response that did not alter maternal food intake, body weight or litter size and weight. As adults, one prenatal CVS (PCVS) and one non-stressed (NS) male were housed in the VBS with adult females. Although there were no overt differences between PCVS and NS male offspring prior to VBS housing, a greater percentage of PCVS males became SUB. However, the depressive-like phenotype of SUB males was not exacerbated in PCVS males; rather, they appeared to better cope with SUB status than NS SUB males. They had lower basal plasma corticosterone than NS SUB males at the end of VBS housing. In situ hybridization for CRH in the PVN and CeA did not reveal any prenatal treatment or status effects, while NPY expression was higher within the MeA of dominant and subordinate males exposed to the VBS in comparison with controls, but with no effect of prenatal treatment. These data suggest that prenatal chronic variable stress may confer resilience to offspring when exposed to social stress in adulthood
A Complete Theory of Grand Unification in Five Dimensions
A fully realistic unified theory is constructed, with SU(5) gauge symmetry
and supersymmetry both broken by boundary conditions in a fifth dimension.
Despite the local explicit breaking of SU(5) at a boundary of the dimension,
the large size of the extra dimension allows precise predictions for gauge
coupling unification, alpha_s(M_Z) = 0.118 \pm 0.003, and for Yukawa coupling
unification, m_b(M_Z) = 3.3 \pm 0.2 GeV. A complete understanding of the MSSM
Higgs sector is given; with explanations for why the Higgs triplets are heavy,
why the Higgs doublets are protected from a large tree-level mass, and why the
mu and B parameters are naturally generated to be of order the SUSY breaking
scale. All sources of d=4,5 proton decay are forbidden, while a new origin for
d=6 proton decay is found to be important. Several aspects of flavor follow
from an essentially unique choice of matter location in the fifth dimension:
only the third generation has an SU(5) mass relation, and the lighter two
generations have small mixings with the heaviest generation. The entire
superpartner spectrum is predicted in terms of only two free parameters. The
squark and slepton masses are determined by their location in the fifth
dimension, allowing a significant experimental test of the detailed structure
of the extra dimension. Lepton flavor violation is found to be generically
large in higher dimensional unified theories with high mediation scales of SUSY
breaking. In our theory this forces a common location for all three neutrinos,
predicting large neutrino mixing angles. Rates for mu -> e gamma, mu -> e e e,
mu -> e conversion and tau -> mu gamma are larger in our theory than in
conventional 4D supersymmetric GUTs. Proposed experiments probing mu -> e
transitions will probe the entire interesting parameter space of our theory.Comment: 51 pages, late
Solvable Models of Domain Walls in N=1 Supergravity
A class of exactly solvable models of domain walls are worked out in D=4
supergravity. We develop a method to embed globally supersymmetric
theories with exact BPS domain wall solutions into supergravity, by introducing
a gravitationally deformed superpotential. The gravitational deformation is
natural in the spirit of maintaining the K\"ahler invariance. The solutions of
the warp factor and the Killing spinor are also obtained. We find that three
distinct behaviors of warp factors arise depending on the value of a constant
term in the superpotential : exponentially decreasing in both sides of the
wall, flat in one side and decreasing in the other, and increasing in one side
and decreasing in the other. Only the first possibility gives the localized
massless graviton zero mode. Models with multi-walls and models with runaway
vacua are also discussed.Comment: 10 pages, 3 figures; Misprints in three formulas are correcte
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