610 research outputs found
Partially composite 2-Higgs-doublet model
In the extra dimensional scenarios with gauge fields in the bulk, the
Kaluza-Klein (KK) gauge bosons can induce Nambu-Jona-Lasinio (NJL) type
attractive four-fermion interactions, which can break electroweak symmetry
dynamically with accompanying composite Higgs fields. We consider a possibility
that electroweak symmetry breaking (EWSB) is triggered by both a fundamental
Higgs and a composite Higgs arising in a dynamical symmetry breaking mechanism
induced by a new strong dynamics. The resulting Higgs sector is a partially
composite two-Higgs doublet model with specific boundary conditions on the
coupling and mass parameters originating at a compositeness scale .
The phenomenology of this model is discussed including the collider
phenomenology at LHC and ILC.Comment: To appear in the proceeding of LCWS06, Bangalore, Indi
Anomaly Mediated Supersymmetry Breaking in Four Dimensions, Naturally
We present a simple four-dimensional model in which anomaly mediated
supersymmetry breaking naturally dominates. The central ingredient is that the
hidden sector is near a strongly-coupled infrared fixed-point for several
decades of energy below the Planck scale. Strong renormalization effects then
sequester the hidden sector from the visible sector. Supersymmetry is broken
dynamically and requires no small input parameters. The model provides a
natural and economical explanation of the hierarchy between the
supersymmetry-breaking scale and the Planck scale, while allowing anomaly
mediation to address the phenomenological challenges posed by weak scale
supersymmetry. In particular, flavor-changing neutral currents are naturally
near their experimental limits.Comment: 14 pages, Late
Partially Composite Higgs in Supersymmetry
We propose a framework for natural breaking of electroweak symmetry in
supersymmetric models, where elementary Higgs fields are semi-perturbatively
coupled to a strong superconformal sector. The Higgs VEVs break conformal
symmetry in the strong sector at the TeV scale, and the strong sector in turn
gives important contributions to the Higgs potential, giving rise to a kind of
Higgs bootstrap. A Higgs with mass 125\GeV can be accommodated without any
fine tuning. A Higgsino mass of order the Higgs mass is also dynamically
generated in these models. The masses in the strong sector generically violate
custodial symmetry, and a good precision electroweak fit requires tuning of
order . The strong sector has an approximately supersymmetric
spectrum of hadrons at the TeV scale that can be observed by looking for a peak
in the invariant mass distribution, as well as final states containing
multiple , , and Higgs bosons. The models also generically predict large
corrections (either enhancement or suppression) to the h \to \ga\ga width.Comment: 31 page
Improved Single Sector Supersymmetry Breaking
Building on recent work by N. Arkani-Hamed and the present authors, we
construct realistic models that break supersymmetry dynamically and give rise
to composite quarks and leptons, all in a single strongly-coupled sector. The
most important improvement compared to earlier models is that the
second-generation composite states correspond to dimension-2 "meson" operators
in the ultraviolet. This leads to a higher scale for flavor physics, and gives
a completely natural suppression of flavor-changing neutral currents. We also
construct models in which the hierarchy of Yukawa couplings is explained by the
dimensionality of composite states. These models provide an interesting and
viable alternative to gravity- and gauge-mediated models. The generic
signatures are unification of scalar masses with different quantum numbers at
the compositeness scale, and lighter gaugino, Higgsino, and third-generation
squark and slepton masses. We also analyze large classes of models that give
rise to both compositeness and supersymmetry breaking, based on gauge theories
with confining, fixed-point, or free-magnetic dynamics.Comment: 34 pages, LaTeX2
A Minimal Superstring Standard Model I: Flat Directions
Three family SU(3)_C x SU(2)_L x U(1)_Y string models in several
constructions generically possess two features: (i) an extra local anomalous
U(1)_A and (ii) numerous (often fractionally charged) exotic particles beyond
those in the minimal supersymmetric model (MSSM). Recently, we demonstrated
that the observable sector effective field theory of such a free fermionic
string model can reduce to that of the MSSM, with the standard observable gauge
group being just SU(3)_C x SU(2)_L x U(1)_Y and the SU(3)_C x SU(2)_L x
U(1)_Y-charged spectrum of the observable sector consisting solely of the MSSM
spectrum. An example of a model with this property was shown. We continue our
investigation of this model by presenting a large set of different flat
directions of the same model that all produce the MSSM spectrum. Our results
suggest that even after imposing the conditions for the decoupling of exotic
states, there may remain sufficient freedom to satisfy the remaining
phenomenological constraints imposed by the observed data.Comment: 64 pages. Latex. Revisions to match version in Int. J. Mod. Physics
"Gaugomaly" Mediated SUSY Breaking and Conformal Sequestering
Anomaly-mediated supersymmetry breaking in the context of 4D conformally
sequestered models is combined with Poppitz-Trivedi D-type gauge-mediation. The
implementation of the two mediation mechanisms naturally leads to visible soft
masses at the same scale so that they can cooperatively solve the mu and flavor
problems of weak scale supersymmetry, as well as the tachyonic slepton problem
of pure anomaly-mediation. The tools are developed in a modular fashion for
more readily fitting into the general program of optimizing supersymmetric
dynamics in hunting for the most attractive weak scale phenomenologies combined
with Planck-scale plausibility.Comment: 14 pages, Late
Duality between simple-group gauge theories and some applications
In this paper we investigate N=1 supersymmetric gauge theories with a product
gauge group. By using smoothly confining dynamics, we can find new dualities
which include higher-rank tensor fields, and in which the dual gauge group is
simple, not a product. Some of them are dualities between chiral and non-chiral
gauge theories. We also discuss some applications to dynamical supersymmetry
breaking phenomena and new confining theories with a tree-level superpotential.Comment: 33 pages, LaTeX, references added, version to appear in PR
Composite Quarks and Leptons from Dynamical Supersymmetry Breaking without Messengers
We present new theories of dynamical SUSY breaking in which the strong
interactions that break SUSY also give rise to composite quarks and leptons
with naturally small Yukawa couplings. In these models, SUSY breaking is
communicated directly to the composite fields without ``messenger''
interactions. The compositeness scale can be anywhere between 10 TeV and the
Planck scale. These models can naturally solve the supersymmetric flavor
problem, and generically predict sfermion mass unification independent from
gauge unification.Comment: 27 pages, LaTeX; Clarified flavor symmetry of strong interactions;
corrected overestimate of FCNC's; conclusions strengthene
Quasilocalized gravity without asymptotic flatness
We present a toy model of a generic five-dimensional warped geometry in which
the 4D graviton is not fully localized on the brane. Studying the tensor sector
of metric perturbation around this background, we find that its contribution to
the effective gravitational potential is of 4D type (1/r) at the intermediate
scales and that at the large scales it becomes 1/r^{1+alpha}, 0<alpha=< 1 being
a function of the parameters of the model (alpha=1 corresponds to the
asymptotically flat geometry). Large-distance behavior of the potential is
therefore not necessarily five-dimensional. Our analysis applies also to the
case of quasilocalized massless particles other than graviton.Comment: 9 pages, 1 figure; to be published in Phys. Rev.
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