240,442 research outputs found
Possibility of observing MSSM charged Higgs in association with a W boson at LHC
Possibility of observing associated production of charged Higgs and W boson
in the framework of MSSM at LHC is studied. Both leptonic and hadronic decays
of W boson are studied while the charged Higgs boson is considered to decay to
a lepton and a neutrino. Therefore two search categories are defined
based on the leptonic and hadronic final states, i.e.
and where or and is a light jet from
decay. The discovery chance of the two categories is evaluated at an
integrated luminosity of 300 \invfb at LHC. It is shown that both leptonic and
hadronic final states have the chance of discovery at high \tanb. Finally
and contours are provided for both search categories.Comment: 20 pages, 19 figure
Froissart Bound on Total Cross-section without Unknown Constants
We determine the scale of the logarithm in the Froissart bound on total
cross-sections using absolute bounds on the D-wave below threshold for
scattering. E.g. for scattering we show that for c.m. energy
, where .Comment: 6 page
Froissart Bound on Inelastic Cross Section Without Unknown Constants
Assuming that axiomatic local field theory results hold for hadron
scattering, Andr\'e Martin and S. M. Roy recently obtained absolute bounds on
the D-wave below threshold for pion-pion scattering and thereby determined the
scale of the logarithm in the Froissart bound on total cross sections in terms
of pion mass only. Previously, Martin proved a rigorous upper bound on the
inelastic cross-section which is one-fourth of the
corresponding upper bound on , and Wu, Martin,Roy and Singh
improved the bound by adding the constraint of a given . Here we
use unitarity and analyticity to determine, without any high energy
approximation, upper bounds on energy averaged inelastic cross sections in
terms of low energy data in the crossed channel. These are Froissart-type
bounds without any unknown coefficient or unknown scale factors and can be
tested experimentally. Alternatively, their asymptotic forms,together with the
Martin-Roy absolute bounds on pion-pion D-waves below threshold, yield absolute
bounds on energy-averaged inelastic cross sections. E.g. for
scattering, defining ,we show that for c.m. energy ,
where . This bound is
asymptotically one-fourth of the corresponding Martin-Roy bound on the total
cross section, and the scale factor is one-fourth of the scale factor in
the total cross section bound. The average over the interval (s,2s) of the
inelastic cross section has a bound of the same form with
replaced by .Comment: 9 pages. Submitted to Physical Review
The Overlap Package
Camera traps - cameras linked to detectors so that they fire when an animal is present - are a major source of information on the abundance and habitat preferences of rare or shy forest animals. Modern cameras record the time of the photo, and the use of this to investigate diel activity patterns was immediately recognised (Gri?ffiths and van Schaik, 1993). Initially this resulted in broad classfication of taxa as diurnal, nocturnal, crepuscular, or cathemeral (van Schaik and Gri?ths, 1996). More recently, researchers have compared activity
patterns among species to see how overlapping patterns may relate to competition or predation (Linkie and Ridout, 2011; Carver et al., 2011; Ramesh et al., 2012; Carter et al., 2012; Kamler et al., 2012; Ross et al., 2013).
Ridout and Linkie (2009) presented methods to fit kernel density functions to times of observations of animals and to estimate the coe?cient of overlapping, a quantitative measure ranging from 0 (no overlap) to 1 (identical activity patterns). The code they used forms the basis of the overlap package. Although motivated by the analysis of camera trap data, overlap could be applied to data from other sources such as data loggers, provided data collection is carried out around the clock. Nor is it limited to diel cycles: tidal cycles or seasonal cycles, such as plant flowering or fruiting or animal breeding seasons could also be investigated
Effect of habituation on the susceptibility of the rat to restraint ulcers
The frequency and gravity of restraint ulcers were found to significantly diminish in rats previously exposed to brief periods of immobilization. The rats' becoming habituated to restraint conditions probably explains this phenomenon
Assessment of W1 and W2 theories for the computation of electron affinities, ionization potentials, heats of formation, and proton affinities
The performance of two recent {\em ab initio} computational thermochemistry
schemes, W1 and W2 theory [J.M.L. Martin and G. de Oliveira, J. Chem. Phys.
111, 1843 (1999}], is assessed for an enlarged sample of thermochemical data
consisting of the ionization potentials and electron affinities in the G2-1 and
G2-2 sets, as well as the heats of formation in the G2-1 and a subset of the
G2-2 set. We find W1 theory to be several times more accurate for ionization
potentials and electron affinities than commonly used (and less expensive)
computational thermochemistry schemes such as G2, G3, and CBS-QB3: W2 theory
represents a slight improvement for electron affinities but no significant one
for ionization potentials. The use of a two-point rather than a
three-point extrapolation for the SCF component greatly enhances the
numerical stability of the W1 method for systems with slow basis set
convergence. Inclusion of first-order spin-orbit coupling is essential for
accurate ionization potentials and electron affinities involving degenerate
electronic states: inner-shell correlation is somewhat more important for
ionization potentials than for electron affinities, while scalar relativistic
effects are required for the highest accuracy. The mean deviation from
experiment for the G2-1 heats of formation is within the average experimental
uncertainty. W1 theory appears to be a valuable tool for obtaining benchmark
quality proton affinities.Comment: Journal of Chemical Physics, in press (303115JCP). 2 RevTeX files,
first is text and tables, second is E-PAPS tables S-1 through S-5. Additional
supplementary material (total energies, basis function exponents) available
at http://theochem.weizmann.ac.il/web/papers/w1w2.htm
Quantum fields, dark matter and non-standard Wigner classes
The Elko field of Ahluwalia and Grumiller is a quantum field for massive
spin-1/2 particles. It has been suggested as a candidate for dark matter. We
discuss our attempts to interpret the Elko field as a quantum field in the
sense of Weinberg. Our work suggests that one should investigate quantum fields
based on representations of the full Poincar\'e group which belong to one of
the non-standard Wigner classes.Comment: 6 pages. Submitted to proceedings of Dark2009, Christchurch, New
Zealand, January 200
The largest oxigen bearing organic molecule repository
We present the first detection of complex aldehydes and isomers in three
typical molecular clouds located within 200pc of the center of our Galaxy.
We find very large abundances of these complex organic molecules (COMs) in
the central molecular zone (CMZ), which we attribute to the ejection of COMs
from grain mantles by shocks. The relative abundances of the different COMs
with respect to that of CH3OH are strikingly similar for the three sources,
located in very different environments in the CMZ. The similar relative
abundances point toward a unique grain mantle composition in the CMZ. Studying
the Galactic center clouds and objects in the Galactic disk having large
abundances of COMs, we find that more saturated molecules are more abundant
than the non-saturated ones. We also find differences between the relative
abundance between COMs in the CMZ and the Galactic disk, suggesting different
chemical histories of the grain mantles between the two regions in the Galaxy
for the complex aldehydes. Different possibilities for the grain chemistry on
the icy mantles in the GC clouds are briefly discussed. Cosmic rays can play an
important role in the grain chemistry. With these new detections, the molecular
clouds in the Galactic center appear to be one of the best laboratories for
studying the formation of COMs in the Galaxy.Comment: 20 pages, 4 figures, accepted in Ap
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