49,518 research outputs found
RG-invariant Sum Rule in a Generalization of Anomaly Mediated SUSY Breaking Models
We study a generalization of anomaly-mediated supersymmetry breaking (AMSB)
scenarios, under the assumption that the effects of the high-scale theory do
not completely decouple and D-term type contributions can be therefore present.
We investigate the effect of such possible D-term additional contributions to
soft scalar masses by requiring that, for non-vanishing, renormalizable Yukawa
couplings , the sum of squared soft supersymmetry breaking mass
parameters, , is RG-invariant, in the sense
that it becomes independent of the specific ultraviolet boundary conditions as
it occurs in the AMSB models. These type of models can avoid the problem of
tachyonic solutions for the slepton mass spectrum present in AMSB scenarios. We
implement the electroweak symmetry breaking condition and explore the sparticle
spectrum associated with this framework. To show the possible diversity of the
sparticle spectrum, we consider two examples, one in which the D-terms induce a
common soft supersymmetry breaking mass term for all sfermion masses, and
another one in which a light stop can be present in the spectrum.Comment: 24 pages, latex, 12 figure
New fermion mass textures from anomalous U(1) symmetries with baryon and lepton number conservation
In this paper, we present solutions to the fermion mass hierarchy problem in
the context of the minimal supersymmetric standard theory augmented by an
anomalous family-dependent U(1)_X symmetry. The latter is spontaneously broken
by non-zero vevs of a pair of singlet fields whose magnitude is determined
through the D- and F-flatness conditions of the superpotential. We derive the
general solutions to the anomaly cancellation conditions and show that they
allow numerous choices for the U(1)_X fermion charges which give several
fermion mass textures in agreement with the observed fermion mass hierarchy and
mixing. Solutions with U(1)_X fermion charge assignments are found which forbid
or substantially suppress the dangerous baryon and lepton number violating
operators and the lepton-higgs mixing coupling while a higgs mixing mass
(\mu-term) can be fixed at the electroweak level. We give a general
classification of the fermion mass textures with respect to the sum of the
doublet-higgs U(1)_X-charges and show that suppression of dimension-five
operators naturally occurs for various charge assignments. We work out cases
which retain a quartic term providing the left-handed neutrinos with Majorana
masses in the absence of right-handed neutrino components and consistent with
the experimental bounds. Although there exist solutions which naturally combine
all the above features with rather natural U(1)_X charges, the suppression of
the \mu-term occurs for particular assignments.Comment: 32 page
Toward a coherent solution of diphoton and flavor anomalies
We propose a coherent explanation for the 750 GeV diphoton anomaly and the
hints of deviations from Lepton Flavor Universality in B decays in terms a new
strongly interacting sector with vectorlike confinement. The diphoton excess
arises from the decay of one of the pseudo-Nambu-Goldstone bosons of the new
sector, while the flavor anomalies are a manifestation of the exchange of the
corresponding vector resonances (with masses in the 1.5-2.5 TeV range). We
provide explicit examples (with detailed particle content and group structure)
of the new sector, discussing both the low-energy flavor-physics phenomenology
and the signatures at high . We show that specific models can provide an
excellent fit to all available data. A key feature of all realizations is a
sizable broad excess in the tails of invariant mass
distribution in , that should be accessible at the LHC
in the near future.Comment: v2: 32 pages, 9 figures, 2 tables. Published version. Extended
discussion about the flavor structure of the model and high-PT phenomenology,
typos corrected. Added note about the relevance of the paper in light of the
absence of the diphoton signal at the LH
Morse Inequalities for Orbifold Cohomology
This paper begins the study of Morse theory for orbifolds, or more precisely
for differentiable Deligne-Mumford stacks. The main result is an analogue of
the Morse inequalities that relates the orbifold Betti numbers of an
almost-complex orbifold to the critical points of a Morse function on the
orbifold. We also show that a generic function on an orbifold is Morse. In
obtaining these results we develop for differentiable Deligne-Mumford stacks
those tools of differential geometry and topology -- flows of vector fields,
the strong topology -- that are essential to the development of Morse theory on
manifolds
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