2,188 research outputs found
Herd behavior, the "Penguin effect", and the suppression of informational diffusion: An analysis of informational externalities and payoff interdependency
Technology;Information;Econometric Models;Group Behaviour
Herd behavior, the "Penguin effect", and the suppression of informational diffusion:An analysis of informational externalities and payoff interdependency
Gaugino and Scalar Masses in the Landscape
In this letter we demonstrate the genericity of suppressed gaugino masses M_a
\sim m_{3/2}/ln(M_P/m_{3/2}) in the IIB string landscape, by showing that this
relation holds for D7-brane gauginos whenever the associated modulus is
stabilised by nonperturbative effects. Although m_{3/2} and M_a take many
different values across the landscape, the above small mass hierarchy is
maintained. We show that it is valid for models with an arbitrary number of
moduli and applies to both the KKLT and exponentially large volume approaches
to Kahler moduli stabilisation. In the latter case we explicitly calculate
gaugino and moduli masses for compactifications on the two-modulus Calabi-Yau
P^4_[1,1,1,6,9]. In the large-volume scenario we also show that soft scalar
masses are approximately universal with m_i^2 \sim m_{3/2}^2 (1 + \epsilon_i),
with the non-universality parametrised by \epsilon_i \sim 1/ln (M_P/m_{3/2})^2
\sim 1/1000. We briefly discuss possible phenomenological implications of our
results.Comment: 15 pages, JHEP style; v2. reference adde
Systematics of String Loop Corrections in Type IIB Calabi-Yau Flux Compactifications
We study the behaviour of the string loop corrections to the N=1 4D
supergravity Kaehler potential that occur in flux compactifications of IIB
string theory on general Calabi-Yau three-folds. We give a low energy
interpretation for the conjecture of Berg, Haack and Pajer for the form of the
loop corrections to the Kaehler potential. We check the consistency of this
interpretation in several examples. We show that for arbitrary Calabi-Yaus, the
leading contribution of these corrections to the scalar potential is always
vanishing, giving an "extended no-scale structure". This result holds as long
as the corrections are homogeneous functions of degree -2 in the 2-cycle
volumes. We use the Coleman-Weinberg potential to motivate this cancellation
from the viewpoint of low-energy field theory. Finally we give a simple formula
for the 1-loop correction to the scalar potential in terms of the tree-level
Kaehler metric and the correction to the Kaehler potential. We illustrate our
ideas with several examples. A companion paper will use these results in the
study of Kaehler moduli stabilisation.Comment: 34 pages and 3 figures; typos corrected and references adde
Scanning the Landscape of Flux Compactifications: Vacuum Structure and Soft Supersymmetry Breaking
We scan the landscape of flux compactifications for the Calabi-Yau manifold
with two K\" ahler moduli by varying the value of
the flux superpotential over a large range of values. We do not include
uplift terms. We find a rich phase structure of AdS and dS vacua. Starting with
we reproduce the exponentially large volume scenario, but as
is reduced new classes of minima appear. One of them corresponds to the
supersymmetric KKLT vacuum while the other is a new, deeper non-supersymmetric
minimum. We study how the bare cosmological constant and the soft supersymmetry
breaking parameters for matter on D7 branes depend on , for these classes
of minima. We discuss potential applications of our results.Comment: draft format remove
The Gaugino Code
Gauginos might play a crucial role in the search for supersymmetry at the
Large Hadron Collider (LHC). Mass predictions for gauginos are rather robust
and often related to the values of the gauge couplings. We analyse the ratios
of gaugino masses in the LHC energy range for various schemes of supersymmetry
breakdown and mediation. Three distinct mass patterns emerge.Comment: 42 pages, Latex; a discussion of deflected anomaly mediation added,
references adde
String theoretic QCD axion with stabilized saxion and the pattern of supersymmetry breaking
String theoretic axion is a prime candidate for the QCD axion solving the
strong CP problem. For a successful realization of the QCD axion in string
theory, one needs to stabilize moduli including the scalar partner (saxion) of
the QCD axion, while keeping the QCD axion unfixed until the low energy QCD
instanton effects are turned on. We note that a simple generalization of KKLT
moduli stabilization provides such set-up realizing the axion solution to the
strong CP problem. Although some details of moduli stabilization are different
from the original KKLT scenario, this set-up leads to the mirage mediation
pattern of soft SUSY breaking terms as in the KKLT case, preserving flavor and
CP as a consequence of approximate scaling and axionic shift symmetries. The
set-up also gives an interesting pattern of moduli masses which might avoid the
cosmological moduli, gravitino and axion problems.Comment: JHEP style, 21 pages, 3 figures; typos correcte
CP Test in the W Pair Production via Photon Fusion at NLC
We study the possibility to test CP invariance in the production via
photon fusion at NLC. The predictions of the CP violation effects are made
within two Higgs doublet extensions of the minimal standard model, where CP
violation is introduced by a neutral Higgs exchange in s channel in our case.
The width effect in the Higgs propagator on the CP violation effects is studied
in detail. The CP violation effects can be measured in some parameter region of
the extensions.Comment: 11 pages, Tex, UM-P-93/16, OZ-93/6 One figure not include
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