2,838 research outputs found
Suntracker balloon flights, flights 3026, 3028, 3029, and 3031
Suntracker balloon flight test instrumentatio
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
"Big" Divisor D3/D7 Swiss Cheese Phenomenology
We review progress made over the past couple of years in the field of Swiss
Cheese Phenomenology involving a mobile space-time filling D3-brane and
stack(s) of fluxed D7-branes wrapping the "big" (as opposed to the "small")
divisor in (the orientifold of a) Swiss-Cheese Calabi-Yau. The topics reviewed
include reconciliation of large volume cosmology and phenomenology, evaluation
of soft supersymmetry breaking parameters, one-loop RG-flow equations'
solutions for scalar masses, obtaining fermionic (possibly first two
generations' quarks/leptons) mass scales in the O(MeV-GeV)-regime as well as
(first two generations') neutrino masses (and their one-loop RG flow) of around
an eV. The heavy sparticles and the light fermions indicate the possibility of
"split SUSY" large volume scenario.Comment: Invited review for MPLA, 14 pages, LaTe
Quasirandomness in hypergraphs
An -vertex graph of edge density is considered to be quasirandom
if it shares several important properties with the random graph . A
well-known theorem of Chung, Graham and Wilson states that many such `typical'
properties are asymptotically equivalent and, thus, a graph possessing one
such property automatically satisfies the others.
In recent years, work in this area has focused on uncovering more quasirandom
graph properties and on extending the known results to other discrete
structures. In the context of hypergraphs, however, one may consider several
different notions of quasirandomness. A complete description of these notions
has been provided recently by Towsner, who proved several central equivalences
using an analytic framework. We give short and purely combinatorial proofs of
the main equivalences in Towsner's result.Comment: 19 page
Kahler Potentials of Chiral Matter Fields for Calabi-Yau String Compactifications
The Kahler potential is the least understood part of effective N=1
supersymmetric theories derived from string compactifications. Even at
tree-level, the Kahler potential for the physical matter fields, as a function
of the moduli fields, is unknown for generic Calabi-Yau compactifications and
has only been computed for simple toroidal orientifolds. In this paper we
describe how the modular dependence of matter metrics may be extracted in a
perturbative expansion in the Kahler moduli. Scaling arguments, locality and
knowledge of the structure of the physical Yukawa couplings are sufficient to
find the relevant Kahler potential. Using these techniques we compute the
`modular weights' for bifundamental matter on wrapped D7 branes for
large-volume IIB Calabi-Yau flux compactifications. We also apply our
techniques to the case of toroidal compactifications, obtaining results
consistent with those present in the literature. Our techniques do not provide
the complex structure moduli dependence of the Kahler potential, but are
sufficient to extract relevant information about the canonically normalised
matter fields and the soft supersymmetry breaking terms in gravity mediated
scenarios.Comment: JHEP style, 24 pages, 4 figures. v2: New section and reference adde
Field Identifications for Interacting Bosonic Models in N=2 Superconformal Field Theory
We study a family of interacting bosonic representations of the N=2 superconformal algebra. These models can be tensored with a conjugate theory to give the free theory. We explain how to use free fields to study interacting fields and their dimensions, and how we may identify different free fields as representing the same interacting field. We show how a lattice of identifying fields may be built up and how every free field may be reduced to a standard form, thus permitting the resolution of the spectrum. We explain how to build the extended algebra and show that there are a finite number of primary fields for this algebra for any of the models. We illustrate this by studying an example
On the Effective Description of Large Volume Compactifications
We study the reliability of the Two-Step moduli stabilization in the type-IIB
Large Volume Scenarios with matter and gauge interactions. The general analysis
is based on a family of N=1 Supergravity models with a factorizable Kaehler
invariant function, where the decoupling between two sets of fields without a
mass hierarchy is easily understood. For the Large Volume Scenario particular
analyses are performed for explicit models, one of such developed for the first
time here, finding that the simplified version, where the Dilaton and Complex
structure moduli are regarded as frozen by a previous stabilization, is a
reliable supersymmetric description whenever the neglected fields stand at
their leading F-flatness conditions and be neutral. The terms missed by the
simplified approach are either suppressed by powers of the Calabi-Yau volume,
or are higher order operators in the matter fields, and then irrelevant for the
moduli stabilization rocedure. Although the power of the volume suppressing
such corrections depends on the particular model, up to the mass level it is
independent of the modular weight for the matter fields. This at least for the
models studied here but we give arguments to expect the same in general. These
claims are checked through numerical examples. We discuss how the factorizable
models present a context where despite the lack of a hierarchy with the
supersymmetry breaking scale, the effective theory still has a supersymmetric
description. This can be understood from the fact that it is possible to find
vanishing solution for the auxiliary components of the fields being integrated
out, independently of the remaining dynamics. Our results settle down the
question on the reliability of the way the Dilaton and Complex structure are
treated in type-IIB compactifications with large compact manifold volumina.Comment: 23 pages + 2 appendices (38 pages total). v2: minor improvements,
typos fixed. Version published in JHE
Finite reflection groups and graph norms
Given a graph H on vertex set {1, 2, · · · , n} and a function f : [0, 1]2 → R, define
kfkH :=
Z Y
ij∈E(H)
f(xi
, xj )dµ|V (H)|
1/|E(H)|
,
where µ is the Lebesgue measure on [0, 1]. We say that H is norming if k·kH is a semi-norm.
A similar notion k·kr(H)
is defined by kfkr(H)
:= k|f|kH and H is said to be weakly norming if
k·kr(H)
is a norm. Classical results show that weakly norming graphs are necessarily bipartite. In
the other direction, Hatami showed that even cycles, complete bipartite graphs, and hypercubes
are all weakly norming. We demonstrate that any graph whose edges percolate in an appropriate
way under the action of a certain natural family of automorphisms is weakly norming. This result
includes all previously known examples of weakly norming graphs, but also allows us to identify
a much broader class arising from finite reflection groups. We include several applications of our
results. In particular, we define and compare a number of generalisations of Gowers’ octahedral
norms and we prove some new instances of Sidorenko’s conjectur
Suntracker balloon flights - 3033, 3034, 3035 and 3037 Final report
Preparations, field operations, and instrumentation for suntracker balloon flight
Sparticle Spectra and LHC Signatures for Large Volume String Compactifications
We study the supersymmetric particle spectra and LHC collider observables for
the large-volume string models with a fundamental scale of 10^{11} GeV that
arise in moduli-fixed string compactifications with branes and fluxes. The
presence of magnetic fluxes on the brane world volume, required for chirality,
perturb the soft terms away from those previously computed in the dilute-flux
limit. We use the difference in high-scale gauge couplings to estimate the
magnitude of this perturbation and study the potential effects of the magnetic
fluxes by generating many random spectra with the soft terms perturbed around
the dilute flux limit. Even with a 40% variation in the high-scale soft terms
the low-energy spectra take a clear and predictive form. The resulting spectra
are broadly similar to those arising on the SPS1a slope, but more degenerate.
In their minimal version the models predict the ratios of gaugino masses to be
M_1 : M_2 : M_3=(1.5 - 2) : 2 : 6, different to both mSUGRA and mirage
mediation. Among the scalars, the squarks tend to be lighter and the sleptons
heavier than for comparable mSUGRA models. We generate 10 fb^{-1} of sample LHC
data for the random spectra in order to study the range of collider
phenomenology that can occur. We perform a detailed mass reconstruction on one
example large-volume string model spectrum. 100 fb^{-1} of integrated
luminosity is sufficient to discriminate the model from mSUGRA and aspects of
the sparticle spectrum can be accurately reconstructed.Comment: 42 pages, 21 figures. Added references and discussion for section 3.
Slight changes in the tex
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