108 research outputs found
Extracting Flavor from Quiver Gauge Theories
We consider a large class of models where an SU(5) gauge symmetry and a
Froggatt-Nielsen (FN) Abelian flavor symmetry arise from a quiver gauge theory.
Such quiver models are very restrictive and therefore have strong predictive
power. In particular, under mild assumptions neutrino mass anarchy is
predicted.Comment: 4 pages, 1 figure, to appear in Proceedings of SUSY06, the 14th
International Conference on Supersymmetry and the Unification of Fundamental
Interactions, UC Irvine, California, 12-17 June 200
Dynamical Supersymmetry Breaking from Simple Quivers
We construct a simple local model of dynamical supersymmetry breaking. The
model is a one generation SU(5) that arises from a IIB Z_N orientifold. It does
not admit a runaway direction and is argued to stabilize the blowup mode
related to the corresponding U(1) factor. The theory demonstrates the existence
of a new class of "blowup" fractional branes. We further discuss a compact
realization of the quiver on a Calabi-Yau 3-fold which enables one to add
fluxes and stabilize the complex structure moduli.Comment: 4 pages, revtex4; An error was corrected following [arXiv:0707.0298
Implications of Higgs Searches on the Four Generation Standard Model
Within the four generation Standard Model, the Higgs couplings to gluons and
to photons deviate in a significant way from the predictions of the three
generation Standard Model. As a consequence, large departures in several Higgs
production and decay channels are expected. Recent Higgs search results,
presented by ATLAS, CMS and CDF, hint on the existence of a Higgs boson with a
mass around 125 GeV. Using these results and assuming such a Higgs boson, we
derive exclusion limits on the four generation Standard Model. For m_H = 125
GeV, the model is excluded at 99.9% confidence level. For 124 GeV <= m_H <= 127
GeV, an exclusion limit above 95% confidence level is found.Comment: 4 pages, 2 figures; v2: updated LHC results, refined sca
Semi-direct Gauge Mediation
We describe a framework for gauge mediation of supersymmetry breaking in
which the messengers are charged under the hidden sector gauge group but do not
play a role in breaking supersymmetry. From this point of view, our framework
is between ordinary gauge mediation and direct mediation. As an example, we
consider the 3-2 model of dynamical supersymmetry breaking, and add to it
massive messengers which are SU(2) doublets. We briefly discuss the
phenomenology of this scenario.Comment: 24 pages. v2: Typos corrected and reference added. v3: Reference
adde
Hybrid Inflation and the Moduli Problem
We revisit some questions in supersymmetric hybrid inflation (SHI). We
analyze the amount of fine tuning required in various models, the problem of
decay at the end of inflation and the generation of baryons after inflation. We
find that the most natural setting for HI is in supersymmetric models with
non-renormalizable couplings. Furthermore, we argue that almost inevitably, one
of the fields involved is a modulus, with Planck scale variation. The resulting
moduli problem can be solved in two ways: either by a massive modulus (which
requires some fine tuning), or an enhanced symmetry point, in which the moduli
becomes strongly coupled to the Standard Model. Various possibilities for
baryon production are discussed.Comment: 19 page
Odd Tracks at Hadron Colliders
New physics that exhibits irregular tracks such as kinks, intermittent hits
or decay in flight may easily be missed at hadron colliders. We demonstrate
this by studying viable models of light, O(10 GeV), colored particles that
decay predominantly inside the tracker. Such particles can be produced at
staggering rates, and yet may not be identified or even triggered on at the
LHC, unless specifically searched for. In addition, the models we study provide
an explanation for the original measurement of the anomalous charged track
distribution by CDF. The presence of irregular tracks in these models reconcile
that measurement with the subsequent reanalysis and the null results of ATLAS
and CMS. Our study clearly illustrates the need for a comprehensive study of
irregular tracks at the LHC.Comment: 6 pages, 1 figur
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