3,204 research outputs found
The Modified Weighted Slab Technique: Models and Results
In an attempt to understand the source and propagation of galactic cosmic
rays we have employed the Modified Weighted Slab technique along with recent
values of the relevant cross sections to compute primary to secondary ratios
including B/C and Sub-Fe/Fe for different galactic propagation models. The
models that we have considered are the disk-halo diffusion model, the dynamical
halo wind model, the turbulent diffusion model and a model with minimal
reacceleration. The modified weighted slab technique will be briefly discussed
and a more detailed description of the models will be given. We will also
discuss the impact that the various models have on the problem of anisotropy at
high energy and discuss what properties of a particular model bear on this
issue.Comment: LaTeX - AASTEX format, Submitted to ApJ, 8 figures, 20 page
'Raising the bar' : improving the standard and utility of weed and invasive plant research
Fil: Murray, Justine V.. Water for Healthy Country Flagship; AustraliaFil: Lehnhoff, Erik A.. Montana State University; Estados UnidosFil: Neve, Paul. University of Warwick; Reino UnidoFil: Poggio, Santiago Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Webber, Bruce L.. CSIRO Ecosystems Sciences; Australia. The University of Western Australia; Australi
Topological properties and fractal analysis of recurrence network constructed from fractional Brownian motions
Many studies have shown that we can gain additional information on time
series by investigating their accompanying complex networks. In this work, we
investigate the fundamental topological and fractal properties of recurrence
networks constructed from fractional Brownian motions (FBMs). First, our
results indicate that the constructed recurrence networks have exponential
degree distributions; the relationship between and of recurrence networks decreases with the Hurst
index of the associated FBMs, and their dependence approximately satisfies
the linear formula . Moreover, our numerical results of
multifractal analysis show that the multifractality exists in these recurrence
networks, and the multifractality of these networks becomes stronger at first
and then weaker when the Hurst index of the associated time series becomes
larger from 0.4 to 0.95. In particular, the recurrence network with the Hurst
index possess the strongest multifractality. In addition, the
dependence relationships of the average information dimension on the Hurst index can also be
fitted well with linear functions. Our results strongly suggest that the
recurrence network inherits the basic characteristic and the fractal nature of
the associated FBM series.Comment: 25 pages, 1 table, 15 figures. accepted by Phys. Rev.
Higgs boson production at hadron colliders in the k_T-factorization approach
We consider the Higgs boson production at high energy hadron colliders in the
framework of the k_T-factorization approach. The attention is focused on the
dominant gluon-gluon fusion subprocess. We calculate the total cross section
and transverse momentum distributions of the inclusive Higgs production using
unintegrated gluon distributions in a proton obtained from the full CCFM
evolution equation. We show that k_T-factorization gives a possibility to
investigate the associated Higgs boson and jets production. We calculate the
transverse momentum distributions and study the Higgs-jet and jet-jet azimuthal
correlations in the Higgs + one or two jet production processes. We demonstrate
the importance of the higher-order corrections within the k_T-factorization
approach. These corrections should be developed and taken into account in the
future applications.Comment: 20 pages, 9 figure
The gluon content of the and mesons and the , electromagnetic transition form factors
We compute power-suppressed corrections to the \eta\gamma and
\eta^{\prime}\gamma transition form factors
Q^2F_{\eta(\eta^{\prime})\gamma}(Q^2) arising from the end point regions x \to
0,1 by employing the infrared-renormalon approach. The contribution to the form
factors from the quark and gluon content of the \eta,\eta^{\prime} mesons is
taken into account using for the \eta-\eta^{\prime} mixing the SU_f(3) singlet
\eta_1 and octet \eta_8 basis. The theoretical predictions obtained this way
are compared with the corresponding CLEO data and restrictions on the input
parameters (Gegenbauer coefficients) B_2^q(\eta_1), B_2^g(\eta_1), and
B_2^q(\eta_8) in the distribution amplitudes for the \eta_1,\eta_8 states with
one nonasymptotic term are deduced. Comparison is made with the results from
QCD perturbation theory.Comment: 25 pages, RevTeX4 used. 9 figures as EPS files. Text significantly
changed to include variation of theoretical parameters. Figures modified.
Corrected typo in equation (34) and trivial mistake in -coefficient.
References added. Conclusions unchange
Data acquisition system for the MuLan muon lifetime experiment
We describe the data acquisition system for the MuLan muon lifetime
experiment at Paul Scherrer Institute. The system was designed to record muon
decays at rates up to 1 MHz and acquire data at rates up to 60 MB/sec. The
system employed a parallel network of dual-processor machines and repeating
acquisition cycles of deadtime-free time segments in order to reach the design
goals. The system incorporated a versatile scheme for control and diagnostics
and a custom web interface for monitoring experimental conditions.Comment: 19 pages, 8 figures, submitted to Nuclear Instruments and Methods
Phenolic composition and antioxidant activity in sparkling wines: Modulation by the ageing on lees
AbstractSparkling wines (SW) have a special biological ageing on lees that is performed using two distinct methods: in the bottle (Champenoise) or in isobaric tanks (Charmat method). The objective of this study was to compare the levels of phenolic compounds, β-Glucosidase and antioxidant activity during the ageing on lees, in samples of SW produced at industrial scale by both methods. The β-Glucosidase activity has been constant over time, showing a close relationship with all the polyphenols studied (resveratrol, piceid, tyrosol, gallic, caffeic and ferulic acids), which were affected by the sur lie time. With these cross-reactions, the biological properties of the SW were also modulated. The results showed that the long period of ageing decreased the antioxidant potential in all samples. This work demonstrates that the sur lie is more important than the production method itself, due to its ability to modulate the necessary changes to achieve the specific objective
Analytic Invariant Charge in QCD
This paper gives an overview of recently developed model for the QCD analytic
invariant charge. Its underlying idea is to bring the analyticity condition,
which follows from the general principles of local Quantum Field Theory, in
perturbative approach to renormalization group (RG) method. The concrete
realization of the latter consists in explicit imposition of analyticity
requirement on the perturbative expansion of function for the strong
running coupling, with subsequent solution of the corresponding RG equation. In
turn, this allows one to avoid the known difficulties originated in
perturbative approximation of the RG functions. Ultimately, the proposed
approach results in qualitatively new properties of the QCD invariant charge.
The latter enables one to describe a wide range of the strong interaction
processes both of perturbative and intrinsically nonperturbative nature.Comment: Invited review article; 46 pages, 14 EPS figure
QCD
We discuss QCD studies that will be possible at LEP2. We examine both
experimental and theoretical aspects of jets, fragmentation functions,
multiplicities and particle spectra.Comment: 44 pages, Latex, epsfig, 18 figures, to appear on the Report of the
Workshop on Physics at LEP2, CERN 96-01, vol. 1, 199
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