424 research outputs found
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
The Two Faces of Anomaly Mediation
Anomaly mediation is a ubiquitous source of supersymmetry (SUSY) breaking
which appears in almost every theory of supergravity. In this paper, we show
that anomaly mediation really consists of two physically distinct phenomena,
which we dub "gravitino mediation" and "Kahler mediation". Gravitino mediation
arises from minimally uplifting SUSY anti-de Sitter (AdS) space to Minkowski
space, generating soft masses proportional to the gravitino mass. Kahler
mediation arises when visible sector fields have linear couplings to SUSY
breaking in the Kahler potential, generating soft masses proportional to beta
function coefficients. In the literature, these two phenomena are lumped
together under the name "anomaly mediation", but here we demonstrate that they
can be physically disentangled by measuring associated couplings to the
goldstino. In particular, we use the example of gaugino soft masses to show
that gravitino mediation generates soft masses without corresponding goldstino
couplings. This result naively violates the goldstino equivalence theorem but
is in fact necessary for supercurrent conservation in AdS space. Since
gravitino mediation persists even when the visible sector is sequestered from
SUSY breaking, we can use the absence of goldstino couplings as an unambiguous
definition of sequestering.Comment: 21 pages, 1 table; v2, references added, extended discussion in
introduction and appendix; v3, JHEP versio
Spontaneous Parity Violation in SUSY Strong Gauge Theory
We suggest simple models of spontaneous parity violation in supersymmetric
strong gauge theory. We focus on left-right symmetric model and investigate
vacuum with spontaneous parity violation. Non-perturbative effects are
calculable in supersymmetric gauge theory, and we suggest two new models. The
first model shows confinement, and the second model has a dual description of
the theory. The left-right symmetry breaking and electroweak symmetry breaking
are simultaneously occurred with the suitable energy scale hierarchy. The
second model also induces spontaneous supersymmetry breaking.Comment: 14 page
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
Leptogenesis, Dark Matter and Higgs Phenomenology at TeV
We propose an interesting model of neutrino masses to realize leptogenesis
and dark matter at the TeV scale. A real scalar is introduced to naturally
realize the Majorana masses of the right-handed neutrinos. We also include a
new Higgs doublet that contributes to the dark matter of the universe. The
neutrino masses come from the vacuum expectation value of the triplet Higgs
scalar. The right-handed neutrinos are not constrained by the neutrino masses
and hence they could generate leptogenesis at the TeV scale without subscribing
to resonant leptogenesis. In our model, all new particles could be observable
at the forthcoming Large Hardon Collider or the proposed future International
Linear Collider.Comment: 7 pages, 3 figures. References added. Accepted by NP
Energy's and amplitudes' positivity
In QFT, the null energy condition (NEC) for a classical field configuration
is usually associated with that configuration's stability against small
perturbations, and with the sub-luminality of these. Here, we exhibit an
effective field theory that allows for stable NEC-violating solutions with
exactly luminal excitations only. The model is the recently introduced
`galileon', or more precisely its conformally invariant version. We show that
the theory's low-energy S-matrix obeys standard positivity as implied by
dispersion relations. However we also show that if the relevant NEC-violating
solution is inside the effective theory, then other (generic) solutions allow
for superluminal signal propagation. While the usual association between
sub-luminality and positivity is not obeyed by our example, that between NEC
and sub-luminality is, albeit in a less direct way than usual.Comment: 21 pages. v2: Typos in eq. (2.41) and (2.41) corrected; discussion of
section 2.3 modified accordingly. Other sections and conclusions unchanged.
Matches the Erratum published in JHE
Flavor in Minimal Conformal Technicolor
We construct a complete, realistic, and natural UV completion of minimal
conformal technicolor that explains the origin of quark and lepton masses and
mixing angles. As in "bosonic technicolor", we embed conformal technicolor in a
supersymmetric theory, with supersymmetry broken at a high scale. The exchange
of heavy scalar doublets generates higher-dimension interactions between
technifermions and quarks and leptons that give rise to quark and lepton masses
at the TeV scale. Obtaining a sufficiently large top quark mass requires strong
dynamics at the supersymmetry breaking scale in both the top and technicolor
sectors. This is natural if the theory above the supersymmetry breaking also
has strong conformal dynamics. We present two models in which the strong top
dynamics is realized in different ways. In both models, constraints from
flavor-changing effects can be easily satisfied. The effective theory below the
supersymmetry breaking scale is minimal conformal technicolor with an
additional light technicolor gaugino. We argue that this light gaugino is a
general consequence of conformal technicolor embedded into a supersymmetric
theory. If the gaugino has mass below the TeV scale it will give rise to an
additional pseudo Nambu-Goldstone boson that is observable at the LHC.Comment: 37 pages; references adde
Supersymmetric Model of Neutrino Mass and Leptogenesis with String-Scale Unification
Adjoint supermultiplets (1,3,0) and (8,1,0) modify the evolution of gauge
couplings. If the unification of gauge couplings occurs at the string scale,
their masses are fixed at around GeV. This scale coincides with
expected gaugino condensation scale in the hidden sector GeV. We show how neutrino masses arise in this
unified model which naturally explain the present atmospheric and solar
neutrino data. The out-of-equilibrium decay of the superfield (1,3,0) at
GeV may also lead to a lepton asymmetry which then gets converted
into the present observed baryon asymmetry of the Universe.Comment: Improved by including constraints imposed by gravitino decay, new
references added, corrections and changes made. Accepted for publication in
Physics Letters.
Supersymmetric Triplet Higgs Model of Neutrino Masses and Leptogenesis
We construct a supersymmetric version of the triplet Higgs model for neutrino
masses, which can generate a baryon asymmetry of the Universe through
lepton-number violation and is consistent with the gravitino constraints.Comment: 24 pages, 4 figure
A Model for Neutrino Masses and Dark Matter
We propose a model for neutrino masses that simultaneously results in a new
dark matter candidate, the right-handed neutrino. We derive the dark matter
abundance in this model, show how the hierarchy of neutrino masses is obtained,
and verify that the model is compatible with existing experimental results. The
model provides an economical method of unifying two seemingly separate puzzles
in contemporary particle physics and cosmology.Comment: 4 pages, submitted to PR
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