532 research outputs found
Stability of flux compactifications and the pattern of supersymmetry breaking
We extend the KKLT approach to moduli stabilization by including the dilaton
and the complex structure moduli into the effective supergravity theory.
Decoupling of the dilaton is neither always possible nor necessary for the
existence of stable minima with zero (or positive) cosmological constant. The
pattern of supersymmetry breaking can be much richer than in the decoupling
scenario of KKLT.Comment: References adde
On the Relationship Between First Occupation and Current Occupational Status
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68361/2/10.1177_073088847400100402.pd
The Intermediate Scale Branch of the Landscape
Three branches of the string theory landscape have plausibly been identified.
One of these branches is expected to exhibit a roughly logarithmic distribution
of supersymmetry breaking scales. The original KKLT models are in this class.
We argue that certain features of the KKLT model are generic to this branch,
and that the resulting phenomenology depends on a small set of discrete
choices. As in the MSSM, the weak scale in these theories is tuned; a possible
explanation is selection for the dark matter density.Comment: 16 pages. More thorough analysis; additonal reference
Bounds on masses of bulk fields in string compactifications
In string compactification on a manifold X, in addition to the string scale
and the normal scales of low-energy particle physics, there is a Kaluza-Klein
scale 1/R associated with the size of X. We present an argument that generic
string models with low-energy supersymmetry have, after moduli stabilization,
bulk fields with masses which are parametrically lighter than 1/R. We discuss
the implications of these light states for anomaly mediation and gaugino
mediation scenarios.Comment: 15 page
Pre - Inflationary Clues from String Theory ?
"Brane supersymmetry breaking" occurs in String Theory when the only
available combinations of D-branes and orientifolds are not mutually BPS and
yet do not introduce tree-level tachyon instabilities. It is characterized by
the emergence of a steep exponential potential, and thus by the absence of
maximally symmetric vacua. The corresponding low-energy supergravity admits
intriguing spatially-flat cosmological solutions where a scalar field is forced
to climb up toward the steep potential after an initial singularity, and
additional milder terms can inject an inflationary phase during the ensuing
descent. We show that, in the resulting power spectra of scalar perturbations,
an infrared suppression is typically followed by a pre-inflationary peak that
reflects the end of the climbing phase and can lie well apart from the
approximately scale invariant profile. A first look at WMAP9 raw data shows
that, while the chi^2 fits for the low-l CMB angular power spectrum are clearly
compatible with an almost scale invariant behavior, they display nonetheless an
eye-catching preference for this type of setting within a perturbative string
regime.Comment: 34 pages, LaTeX, 16 eps figures. Relative displacement in fig. 14 and
some typos corrected, references and acknowledgments updated. To appear in
JCA
Large-Volume Flux Compactifications: Moduli Spectrum and D3/D7 Soft Supersymmetry Breaking
We present an explicit calculation of the spectrum of a general class of
string models, corresponding to Calabi-Yau flux compactifications with
h_{1,2}>h_{1,1}>1 with leading perturbative and non-perturbative corrections,
in which all geometric moduli are stabilised as in hep-th/0502058. The volume
is exponentially large, leading to a range of string scales from the Planck
mass to the TeV scale, realising for the first time the large extra dimensions
scenario in string theory. We provide a general analysis of the relevance of
perturbative and non-perturbative effects and the regime of validity of the
effective field theory. We compute the spectrum in the moduli sector finding a
hierarchy of masses depending on inverse powers of the volume. We also compute
soft supersymmetry breaking terms for particles living on D3 and D7 branes. We
find a hierarchy of soft terms corresponding to `volume dominated' F-term
supersymmetry breaking. F-terms for Kahler moduli dominate both those for
dilaton and complex structure moduli and D-terms or other de Sitter lifting
terms. This is the first class of string models in which soft supersymmetry
breaking terms are computed after fixing all geometric moduli. We outline
several possible applications of our results, both for cosmology and
phenomenology and point out the differences with the less generic KKLT vacua.Comment: 64 pages, 4 figures; v2. references added; v3. typos, reference
added, matches published versio
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Gamma-Ray Pulsars
Gamma-ray photons from young pulsars allow the deepest insight into the
properties and interactions of high-energy particles with magnetic and photon
fields in a pulsar magnetosphere. Measurements with the Compton Gamma-Ray
Observatory have led to the detection of nearly ten gamma-ray pulsars. Although
quite a variety of individual signatures is found for these pulsars, some
general characteristics can be summarized: (1) the gamma-ray lightcurves of
most high-energy pulsars show two major peaks with the pulsed emission covering
more than 50% of the rotation, i.e. a wide beam of emission; (2) the gamma-ray
spectra of pulsars are hard (power law index less than 2), often with a
luminosity maximum around 1 GeV. A spectral cutoff above several GeV is found;
(3) the spectra vary with rotational phase indicating different sites of
emission; and (4) the gamma-luminosity scales with the particle flux from the
open regions of the magnetosphere (Goldreich-Julian current).Comment: 9 pages, 9 figures, 2 tables. To appear in the Proceedings of the
270. WE-Heraeus Seminar on Neutron Stars, Pulsars and Supernova Remnants,
Jan. 21-25, 2002, Physikzentrum Bad Honnef, eds W. Becker, H. Lesch & J.
Truemper. Proceedings are available as MPE-Report 27
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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