1,784 research outputs found
Diffractive Higgs boson production at the Tevatron and LHC
Improved possibilities to find the Higgs boson in diffractive events, having
less hadronic activity, depend on whether the cross section is large enough.
Based on the soft color interaction models that successfully describe
diffractive hard scattering at HERA and the Tevatron, we find that only a few
diffractive Higgs events may be produced at the Tevatron, but we predict a
substantial rate at the LHC.Comment: 4 pages, 4 figures, uses Revtex
Heat Treated NiP–SiC Composite Coatings: Elaboration and Tribocorrosion Behaviour in NaCl Solution
Tribocorrosion behaviour of heat-treated NiP and NiP–SiC composite coatings was investigated in a 0.6 M NaCl solution. The tribocorrosion tests were performed in a linear sliding tribometer with an electrochemical cell interface. It was analyzed the influence of SiC particles dispersion in the NiP matrix on current density developed, on coefficient of friction and on wear volume loss. The results showed that NiP–SiC composite coatings had a lower wear volume loss compared to NiP coatings. However, the incorporation of SiC particles into the metallic matrix affects the current density developed by the system during the tribocorrosion test. It was verified that not only the volume of co-deposited particles (SiC vol.%) but also the number of SiC particles per coating area unit (and consequently the SiC particles size) have made influence on the tribocorrosion behaviour of NiP–SiC composite coatings
Revealing the competitive effect of N2 and H2O towards CO2 adsorption in N-rich ordered mesoporous carbons
The incorporation of heteroatoms improves CO2 adsorption on carbon-based materials, but it can also provide some hydrophilic character to the bare-carbon frameworks, making the hypothesis of competitive CO2/H2O adsorption not negligible. In this respect, the CO2 capture is here evaluated through a deep characterization of the sorption properties of N-rich ordered mesoporous carbons under dry and moisture conditions, and in CO2/N2 gas mixtures. The nanocasting strategy is used to obtain N-rich CMK-3-type carbons in one pot by impregnating D-glucosamine hydrochloride, a carbon/nitrogen source, into an SBA-15 silica template followed by pyrolysis treatment at 600, 750, and 900 °C. The fine-tuning of the pyrolysis treatment aims to find the right proportion of micropores and N content, which are important features for selective CO2 adsorption. The highest surface amount of N (11.3 at.%), in particular of the pyridinic type, enhances the CO2/N2 selectivity (1.03 mmol/g of adsorbed CO2 from a 20% CO2 in N2), but also the undesired increment in the H2O uptake. CO2 uptake under competitive CO2/H2O conditions is better preserved with 8.3 at.% of surface nitrogen (1.55, 1.52, 0.61, and 0.89 mmol/g of CO2 at a relative humidity of 0, 25, 50, and 75%, respectively). Interestingly, the N-CMK-3 materials retain their capture properties over repetitive adsorption-desorption cycles in pure CO2. In this respect, a TGA-FTIR study is performed to monitor the reusability of the sorbents after CO2 capture from moist flue gases to assess the effectiveness of the reactivation procedure towards the removal of the adsorbed species
Charged Particle Multiplicity in Diffractive Deep Inelastic Scattering
The recent data from H1 Collaboration on hadron multiplicity in diffractive
DIS has been studied in the framework of perturbative QCD as a function of
invariant diffractive mass. The formulas obtained explain the observed excess
of particle production in diffractive DIS relative to that in DIS and
annihilation. It is shown that the results are sensitive to the quark--gluon
structure of the Pomeron. Namely, the data say in favour of a super-hard gluon
distribution at the initial scale.Comment: 12 pages, 3 figures; to be published in Phys. Rev.
Evolution of the cosmic ray anisotropy above 10^{14} eV
The amplitude and phase of the cosmic ray anisotropy are well established
experimentally between 10^{11} eV and 10^{14} eV. The study of their evolution
into the energy region 10^{14}-10^{16} eV can provide a significant tool for
the understanding of the steepening ("knee") of the primary spectrum. In this
letter we extend the EAS-TOP measurement performed at E_0 around 10^{14} eV, to
higher energies by using the full data set (8 years of data taking). Results
derived at about 10^{14} and 4x10^{14} eV are compared and discussed. Hints of
increasing amplitude and change of phase above 10^{14} eV are reported. The
significance of the observation for the understanding of cosmic ray propagation
is discussed.Comment: 4 pages, 3 figures, accepted for publication on ApJ Letter
Reggeon and pion contributions in semi-exclusive diffractive processes at HERA
A detailed analysis of semi-exclusive diffractive processes in e-p DIS at
HERA, with the diffractive final states in the forward direction is presented.
The contributions of the subleading f_2, \omega, a_2, \rho reggeons and the
pion exchanges to the diffractive structure function with the forward proton or
neutron are estimated. It is found that the (a_2,\rho) reggeons are entirely
responsible for the forward neutron production at x_P < 10^{-3}. The \pi N
production in the forward region is estimated using the Deck mechanism. The
significance of this reaction for the processes measured at HERA, especially
with the leading neutron, is discussed.Comment: Strongly revised version accepted for publication in Phys.Rev.D.
Latex, 14 pages with 5 eps figures include
Implosion hydrodynamics of fast ignition targets
Copyright 2005 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Physics of Plasmas, 12(5), 056312, 2005 and may be found at http://dx.doi.org/10.1063/1.189695
Soft Color Interactions and Diffractive Hard Scattering at the Fermilab Tevatron
An improved understanding of nonperturbative QCD can be obtained by the
recently developed soft color interaction models. Their essence is the
variation of color string-field topologies, giving a unified description of
final states in high energy interactions, e.g., diffractive and nondiffractive
events in ep and ppbar. Here we present a detailed study of such models (the
soft color interaction model and the generalized area law model) applied to
ppbar, considering also the general problem of the underlying event including
beam particle remnants. With models tuned to HERA ep data, we find a good
description also of Tevatron data on production of W, beauty and jets in
diffractive events defined either by leading antiprotons or by one or two
rapidity gaps in the forward or backward regions. We also give predictions for
diffractive J/psi production where the soft exchange mechanism produces both a
gap and a color singlet ccbar state in the same event. This soft color
interaction approach is also compared with Pomeron-based models for
diffraction, and some possibilities to experimentally discriminate between
these different approaches are discussed.Comment: 35 pages, 15 figures, uses REVTeX. Minor changes, version to appear
in Phys. Rev.
Antimicrobial activity of MgB2 powders produced via reactive liquid infiltration method
We report for the first time on the antimicrobial activity of MgB2 powders produced via the Reactive Liquid Infiltration (RLI) process. Samples with MgB2 wt.% ranging from 2% to 99% were obtained and characterized, observing different levels of grain aggregation and of impurity phases. Their antimicrobial activity was tested against Staphylococcus aureus ATCC BAA 1026, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231. A general correlation is observed between the antibacterial activity and the MgB2 wt.%, but the sample microstructure also appears to be very important. RLI-MgB2 powders show better performances compared to commercial powders against microbial strains in the planktonic form, and their activity against biofilms is also very similar
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