1,186 research outputs found
Classical Extended Conformal Algebras Associated with Constrained KP Hierarchy
We examine the conformal property of the second Hamiltonian structure of
constrained KP hierarchy derived by Oevel and Strampp. We find that it
naturallygives a family of nonlocal extended conformal algebras. We give two
examples of such algebras and find that they are similar to Bilal's V algebra.
By taking a gauge transformation one can map the constrained KP hierarchy to
Kuperschmidt's nonstandard Lax hierarchy. We consider the second Hamiltonian
structure in this representation. We show that after mapping the Lax operator
to a pure differential operator the second structure becomes the sum of the
second and the third Gelfand-Dickey brackets defined by this differential
operator. We show that this Hamiltonian structure defines the W-U(1)-Kac-Moody
algebra by working out its conformally covariant form.Comment: NHCU-HEP-94-28, 19 pages (Plain TeX
Extremely High Energy Neutrinos and their Detection
We discuss in some detail the production of extremely high energy (EHE)
neutrinos with energies above 10^18 eV. The most certain process for producing
such neutrinos results from photopion production by EHE cosmic rays in the
cosmic background photon field. However, using assumptions for the EHE cosmic
ray source evolution which are consistent with results from the deep QSO survey
in the radio and X-ray range, the resultant flux of neutrinos from this process
is not strong enough for plausible detection. A measurable flux of EHE
neutrinos may be present, however, if the highest energy cosmic rays which have
recently been detected well beyond 10^20 eV are the result of the annihilation
of topological defects which formed in the early universe. Neutrinos resulting
from such decays reach energies of the grand unification (GUT) scale, and
collisions of superhigh energy neutrinos with the cosmic background neutrinos
initiate neutrino cascading which enhances the EHE neutrino flux at Earth. We
have calculated the neutrino flux including this cascading effect for either
massless or massive neutrinos and we find that these fluxes are conceivably
detectable by air fluorescence detectors now in development. The
neutrino-induced showers would be recognized by their starting deep in the
atmosphere. We evaluate the feasibility of detecting EHE neutrinos this way
using air fluorescence air shower detectors and derive the expected event rate.
Other processes for producing deeply penetrating air showers constitute a
negligible background.Comment: 33 pages, including 12 eps figures, LaTe
Cosmic Ray in the Northern Hemisphere: Results from the Telescope Array Experiment
The Telescope Array (TA) is the largest ultrahigh energy (UHE) cosmic ray
observatory in the northern hemisphere TA is a hybrid experiment with a unique
combination of fluorescence detectors and a stand-alone surface array of
scintillation counters. We will present the spectrum measured by the surface
array alone, along with those measured by the fluorescence detectors in
monocular, hybrid, and stereo mode. The composition results from stereo TA data
will be discussed. Our report will also include results from the search for
correlations between the pointing directions of cosmic rays, seen by the TA
surface array, with active galactic nuclei.Comment: 8 pages 11 figure, Proceedings of the APS Division of Particle and
Fields (DPF) Meeting, Aug 2011, Brown University, Providence, RI, US
Soft-Collinear Factorization and Zero-Bin Subtractions
We study the Sudakov form factor for a spontaneously broken gauge theory
using a (new) Delta -regulator. To be well-defined, the effective theory
requires zero-bin subtractions for the collinear sectors. The zero-bin
subtractions depend on the gauge boson mass M and are not scaleless. They have
both finite and 1/epsilon contributions, and are needed to give the correct
anomalous dimension and low-scale matching contributions. We also demonstrate
the necessity of zero-bin subtractions for soft-collinear factorization. We
find that after zero-bin subtractions the form factor is the sum of the
collinear contributions 'minus' a soft mass-mode contribution, in agreement
with a previous result of Idilbi and Mehen in QCD. This appears to conflict
with the method-of-regions approach, where one gets the sum of contributions
from different regions.Comment: 9 pages, 5 figures. V2:ref adde
Electroweak Corrections using Effective Field Theory: Applications to the LHC
Electroweak Sudakov logarithms at high energy, of the form alpha/sin^2
theta_W^n log^m s/M_{Z,W}^2, are summed using effective theory (EFT) methods.
The exponentiation of Sudakov logarithms and factorization is discussed in the
EFT formalism. Radiative corrections are computed to scattering processes in
the standard model involving an arbitrary number of external particles. The
computations include non-zero particle masses such as the t-quark mass,
electroweak mixing effects which lead to unequal W and Z masses and a massless
photon, and Higgs corrections proportional to the top quark Yukawa coupling.
The structure of the radiative corrections, and which terms are summed by the
EFT renormalization group is discussed in detail. The omitted terms are smaller
than 1%. We give numerical results for the corrections to dijet production,
dilepton production, t-\bar t production, and squark pair production. The
purely electroweak corrections are significant -- about 15% at 1 TeV,
increasing to 30% at 5 TeV, and they change both the scattering rate and
angular distribution. The QCD corrections (which are well-known) are also
computed with the EFT. They are much larger -- about a factor of four at 1 TeV,
increasing to a factor of thirty at 5 TeV. Mass effects are also significant;
the q \bar q -> t \bar t rate is enchanced relative to the light-quark
production rate by 40%.Comment: Additional details added on exponentiation, and the form of the
Sudakov series. Figures darkened to print better. 40 pages, 40 figure
Their Effects on Hypertension in Taiwan
Aim. We assessed obesity, sex, menopause, and gender differences on hypertension in a Hakka-majority Taiwanese sample. Methods. 9621 subjects aged 20 and over participated in this community-based study. Trained nurses collected blood pressure (BP) measurements and anthropometric indices, including weight, height, hip circumference (HC), waist circumference (WC), body mass index (BMI), waist to height ratio (WHtR), and waist to hip ratio (WHR). Results. Levels of systolic and diastolic BP significantly increased at a dose-dependent relationship based on four anthropometric indices (BMI, WC, WHR, and WHtR); the slopes for SBP and DBP differed. After controlling for other covariates using multivariate logistic regression, we found the adjusted odds ratios (OR) of hypertension to be significantly related to the four anthropometric indices. Notably, the effect of obesity on the ORs for hypertension was considerably higher in premenopausal women, but we found no such phenomenon among men. BMI, WC, WHR, and WHtR had significant linear associations with BP. Conclusion. Obesity indices are significantly correlated with the risk of hypertension across gender and age, with BMI having the highest relative potency. The effect of obesity on the risk of hypertension is especially high in premenopausal women, implying a relationship between hormones and hypertension
Determining exciton bandwidth and film microstructure in polythiophene films using linear absorption spectroscopy
We analyze the linear absorption spectrum of regioregular
poly(3-hexylthiophene) films spun from a variety of solvents to probe directly
the film microstructure and how it depends on processing conditions. We
estimate the exciton bandwidth and the percentage of the film composed of
aggregates quantitatively using a weakly interacting H-aggregate model. This
provides a description of the degree and quality of crystallites within the
film and is in turn correlated with thin-film field-effect transistor
characteristics.Comment: Applied Physics Letters (in press); 9 pages, three figure
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