884 research outputs found
A Survey of Lepton Number Violation Via Effective Operators
We survey 129 lepton number violating effective operators, consistent with
the minimal Standard Model gauge group and particle content, of mass dimension
up to and including eleven. Upon requiring that each one radiatively generates
the observed neutrino masses, we extract an associated characteristic cutoff
energy scale which we use to calculate other observable manifestations of these
operators for a number of current and future experimental probes, concentrating
on lepton number violating phenomena. These include searches for neutrinoless
double-beta decay and rare meson, lepton, and gauge boson decays. We also
consider searches at hadron/lepton collider facilities in anticipation of the
LHC and the future ILC. We find that some operators are already disfavored by
current data, while more are ripe to be probed by next-generation experiments.
We also find that our current understanding of lepton mixing disfavors a subset
of higher dimensional operators. While neutrinoless double-beta decay is the
most promising signature of lepton number violation for the majority of
operators, a handful is best probed by other means. We argue that a combination
of constraints from various independent experimental sources will help to
pinpoint the ``correct'' model of neutrino mass, or at least aid in narrowing
down the set of possibilities.Comment: 34 pages, 10 eps figures, 1 tabl
Development of Readout Interconnections for the Si-W Calorimeter of SiD
The SiD collaboration is developing a Si-W sampling electromagnetic
calorimeter, with anticipated application for the International Linear
Collider. Assembling the modules for such a detector will involve special
bonding technologies for the interconnections, especially for attaching a
silicon detector wafer to a flex cable readout bus. We review the interconnect
technologies involved, including oxidation removal processes, pad surface
preparation, solder ball selection and placement, and bond quality assurance.
Our results show that solder ball bonding is a promising technique for the Si-W
ECAL, and unresolved issues are being addressed.Comment: 8 pages + title, 6 figure
Use of models in large-area forest surveys: comparing model-assisted, model-based and hybrid estimation
This paper focuses on the use of models for increasing the precision of estimators in large-area forest surveys. It
is motivated by the increasing availability of remotely sensed data, which facilitates the development of models
predicting the variables of interest in forest surveys. We present, review and compare three different estimation
frameworks where models play a core role: model-assisted, model-based, and hybrid estimation. The first two are
well known, whereas the third has only recently been introduced in forest surveys. Hybrid inference mixes designbased
and model-based inference, since it relies on a probability sample of auxiliary data and a model predicting the
target variable from the auxiliary data..We review studies on large-area forest surveys based on model-assisted, modelbased,
and hybrid estimation, and discuss advantages and disadvantages of the approaches. We conclude that no
general recommendations can be made about whether model-assisted, model-based, or hybrid estimation should be
preferred. The choice depends on the objective of the survey and the possibilities to acquire appropriate field and
remotely sensed data. We also conclude that modelling approaches can only be successfully applied for estimating
target variables such as growing stock volume or biomass, which are adequately related to commonly available
remotely sensed data, and thus purely field based surveys remain important for several important forest parameters.
Keywords: Design-based inference, Model-assisted estimation, Model-based inference, Hybrid inference, National
forest inventory, Remote sensing, Samplin
Testing the Higgs Mechanism in the Lepton Sector with multi-TeV e+e- Collisions
Multi-TeV e+e- collisions provide with a large enough sample of Higgs bosons
to enable measurements of its suppressed decays. Results of a detailed study of
the determination of the muon Yukawa coupling at 3 TeV, based on full detector
simulation and event reconstruction, are presented. The muon Yukawa coupling
can be determined with a relative accuracy of 0.04 to 0.08 for Higgs bosons
masses from 120 GeV to 150 GeV, with an integrated luminosity of 5 inverse-ab.
The result is not affected by overlapping two-photon background.Comment: 6 pages, 2 figures, submitted to J Phys G.: Nucl. Phy
Mobility of thorium ions in liquid xenon
We present a measurement of the Th ion mobility in LXe at 163.0 K and
0.9 bar. The result obtained, 0.2400.011 (stat) 0.011 (syst)
cm/(kV-s), is compared with a popular model of ion transport.Comment: 6.5 pages,
Minkowski Tensors of Anisotropic Spatial Structure
This article describes the theoretical foundation of and explicit algorithms
for a novel approach to morphology and anisotropy analysis of complex spatial
structure using tensor-valued Minkowski functionals, the so-called Minkowski
tensors. Minkowski tensors are generalisations of the well-known scalar
Minkowski functionals and are explicitly sensitive to anisotropic aspects of
morphology, relevant for example for elastic moduli or permeability of
microstructured materials. Here we derive explicit linear-time algorithms to
compute these tensorial measures for three-dimensional shapes. These apply to
representations of any object that can be represented by a triangulation of its
bounding surface; their application is illustrated for the polyhedral Voronoi
cellular complexes of jammed sphere configurations, and for triangulations of a
biopolymer fibre network obtained by confocal microscopy. The article further
bridges the substantial notational and conceptual gap between the different but
equivalent approaches to scalar or tensorial Minkowski functionals in
mathematics and in physics, hence making the mathematical measure theoretic
method more readily accessible for future application in the physical sciences
Combining Lattice QCD Results with Regge Phenomenology in a Description of Quark Distribution Functions
The most striking feature of quark distribution functions transformed to the
longitudinal distance representation is the recognizable separation of small
and large longitudinal distances. While the former are responsible for the
average properties of parton distributions, the latter can be shown to
determine specifically their small- behavior. In this paper we demonstrate
how the distribution at intermediate longitudinal distances can be approximated
by taking into account constraints which follow from the general properties of
parton densities, such as their support and behavior at . We show that
the combined description of small, intermediate, and large longitudinal
distances allows a good approximation of both shape and magnitude of parton
distribution functions. As an application we have calculated low-virtuality C
even and odd (valence) u and d quark parton densities of the nucleon and the
C-even transversity distribution , combining recent QCD sum rules and
lattice QCD results with phenomenological information about their small-
behavior.Comment: LaTeX, 17 pages including 7 figures, shorter version will appear in
Phys. Lett.
Local Anisotropy of Fluids using Minkowski Tensors
Statistics of the free volume available to individual particles have
previously been studied for simple and complex fluids, granular matter,
amorphous solids, and structural glasses. Minkowski tensors provide a set of
shape measures that are based on strong mathematical theorems and easily
computed for polygonal and polyhedral bodies such as free volume cells (Voronoi
cells). They characterize the local structure beyond the two-point correlation
function and are suitable to define indices of
local anisotropy. Here, we analyze the statistics of Minkowski tensors for
configurations of simple liquid models, including the ideal gas (Poisson point
process), the hard disks and hard spheres ensemble, and the Lennard-Jones
fluid. We show that Minkowski tensors provide a robust characterization of
local anisotropy, which ranges from for vapor
phases to for ordered solids. We find that for fluids,
local anisotropy decreases monotonously with increasing free volume and
randomness of particle positions. Furthermore, the local anisotropy indices
are sensitive to structural transitions in these simple
fluids, as has been previously shown in granular systems for the transition
from loose to jammed bead packs
Renormalon Model Predictions for Power-Corrections to Flavour Singlet Deep Inelastic Structure Functions
We analyze power corrections to flavour singlet deep inelastic scattering
structure functions in the framework of the infrared renormalon model. Our
calculations, together with previous results for the non-singlet contribution,
allow to model the x-dependence of higher twist corrections to F_2, F_L and g_1
in the whole x domain.Comment: LaTeX, 25 pages, 8 eps figures included, one figure was added. Final
version for publication in Nucl.Phys.
Low Hydrophobic Mismatch Scores Calculated for HLA-A/B/DR/DQ Loci Improve Kidney Allograft Survival
We evaluated the impact of human leukocyte antigen (HLA) disparity (immunogenicity; IM) on long-term kidney allograft survival. The IM was quantified based on physicochemical properties of the polymorphic linear donor/recipient HLA amino acids (the Cambridge algorithm) as a hydrophobic, electrostatic, amino acid mismatch scores (HMS\AMS\EMS) or eplet mismatch (EpMM) load. High-resolution HLA-A/B/DRB1/DQB1 types were imputed to calculate HMS for primary/re-transplant recipients of deceased donor transplants. The multiple Cox regression showed the association of HMS with graft survival and other confounders. The HMS integer 0-10 scale showed the most survival benefit between HMS 0 and 3. The Kaplan-Meier analysis showed that: the HMS=0 group had 18.1-year median graft survival, a 5-year benefit over HMS\u3e0 group; HMS ≤ 3.0 had 16.7-year graft survival, a 3.8-year better than HMS\u3e3.0 group; and, HMS ≤ 7.8 had 14.3-year grafts survival, a 1.8-year improvement over HMS\u3e7.8 group. Stratification based on EMS, AMS or EpMM produced similar results. Additionally, the importance of HLA-DR with/without -DQ IM for graft survival was shown. In our simulation of 1,000 random donor/recipient pairs, 75% with HMS\u3e3.0 were re-matched into HMS ≤ 3.0 and the remaining 25% into HMS≥7.8: after re-matching, the 13.5 years graft survival would increase to 16.3 years. This approach matches donors to recipients with low/medium IM donors thus preventing transplants with high IM donors
- …