6,369 research outputs found
Pressure test analysis of 200-inch multicell test tank
Pressure test analysis for large multiple cell tank with sectioned ski
Two-Loop Threshold Singularities, Unstable Particles and Complex Masses
The effect of threshold singularities induced by unstable particles on
two-loop observables is investigated and it is shown how to cure them working
in the complex-mass scheme. The impact on radiative corrections around
thresholds is thoroughly analyzed and shown to be relevant for two selected LHC
and ILC applications: Higgs production via gluon fusion and decay into two
photons at two loops in the Standard Model. Concerning Higgs production, it is
essential to understand possible sources of large corrections in addition to
the well-known QCD effects. It is shown that NLO electroweak corrections can
incongruently reach a 10 % level around the WW vector-boson threshold without a
complete implementation of the complex-mass scheme in the two-loop calculation.Comment: LaTeX, 12 pages, 7 figure
NNLO Computational Techniques: the Cases H -> gamma gamma and H -> g g
A large set of techniques needed to compute decay rates at the two-loop level
are derived and systematized. The main emphasis of the paper is on the two
Standard Model decays H -> gamma gamma and H -> g g. The techniques, however,
have a much wider range of application: they give practical examples of general
rules for two-loop renormalization; they introduce simple recipes for handling
internal unstable particles in two-loop processes; they illustrate simple
procedures for the extraction of collinear logarithms from the amplitude. The
latter is particularly relevant to show cancellations, e.g. cancellation of
collinear divergencies. Furthermore, the paper deals with the proper treatment
of non-enhanced two-loop QCD and electroweak contributions to different
physical (pseudo-)observables, showing how they can be transformed in a way
that allows for a stable numerical integration. Numerical results for the
two-loop percentage corrections to H -> gamma gamma, g g are presented and
discussed. When applied to the process pp -> gg + X -> H + X, the results show
that the electroweak scaling factor for the cross section is between -4 % and +
6 % in the range 100 GeV < Mh < 500 GeV, without incongruent large effects
around the physical electroweak thresholds, thereby showing that only a
complete implementation of the computational scheme keeps two-loop corrections
under control.Comment: LaTeX, 70 pages, 8 eps figure
Self-recording portable soil penetrometer
A lightweight portable penetrometer for testing soil characteristics is described. The penetrometer is composed of a handle, data recording, and probe components detachably joined together. The data recording component has an easily removed recording drum which rotates according to the downward force applied on the handle, and a stylus means for marking the drum along its height according to the penetration depth of probe into the soil
Multi-wavelength properties of IGR J05007-7047 (LXP 38.55) and identification as a Be X-ray binary pulsar in the LMC
We report on the results of a 40 d multi-wavelength monitoring of the
Be X-ray binary system IGR J05007-7047 (LXP 38.55). During that period the
system was monitored in the X-rays using the Swift telescope and in the optical
with multiple instruments. When the X-ray luminosity exceeded erg/s
we triggered an XMM-Newton ToO observation. Timing analysis of the photon
events collected during the XMM-Newton observation reveals coherent X-ray
pulsations with a period of 38.551(3) s (1 {\sigma}), making it the 17
known high-mass X-ray binary pulsar in the LMC. During the outburst, the X-ray
spectrum is fitted best with a model composed of an absorbed power law () plus a high-temperature black-body (kT 2 keV) component. By
analysing 12 yr of available OGLE optical data we derived a 30.776(5) d
optical period, confirming the previously reported X-ray period of the system
as its orbital period. During our X-ray monitoring the system showed limited
optical variability while its IR flux varied in phase with the X-ray
luminosity, which implies the presence of a disk-like component adding cooler
light to the spectral energy distribution of the system.Comment: 11 pages, 11 figures, Accepted for publication in MNRA
Recovery of the biological activity in a vineyard soil after landscape redesign: A three-year study using the bait-lamina method
To detect changes in the biological activity (checked as soil animals feeding activity), the bait-lamina test (VON TÖRNE 1990) was used in a vineyard and a fallow soil (old meadow) during a three-year study. Situated in the vine-growing region of Rheinhessen near Mainz, Germany, the vineyard was part of an intensive redesign of the landscape accompanied by soil restoration. In 1994 new grapevines were planted in a two-row-system: 1) uncovered, 'open' soil, 2) green-covered soil (grass and clover). The new vineyard soil was in a 'raw' soil stage (humus: <1.7 %) whereas the fallow soil (reference soil) was undisturbed (humus: approx. 5 %). At the onset of the experiment in spring 1997 the soil faunal feeding activity in the vineyard soil was close to zero while in the fallow soil the activity was 23 %. In the following tests the feeding activity increased in both, the green-covered and uncovered soil; the highest level of feeding activity was finally found in the covered soil. The results indicate that under the local climatic conditions soil faunal activity recovers within a few years after soil restoration and that the rate of biological activity depends on soil management
Constant-temperature molecular-dynamics algorithms for mixed hard-core/continuous potentials
We present a set of second-order, time-reversible algorithms for the
isothermal (NVT) molecular-dynamics (MD) simulation of systems with mixed
hard-core/continuous potentials. The methods are generated by combining
real-time Nose' thermostats with our previously developed Collision Verlet
algorithm [Mol. Phys. 98, 309 (1999)] for constant energy MD simulation of such
systems. In all we present 5 methods, one based on the Nose'-Hoover [Phys. Rev.
A 31, 1695 (1985)] equations of motion and four based on the Nose'-Poincare'
[J.Comp.Phys., 151 114 (1999)] real-time formulation of Nose' dynamics. The
methods are tested using a system of hard spheres with attractive tails and all
correctly reproduce a canonical distribution of instantaneous temperature. The
Nose'-Hoover based method and two of the Nose'-Poincare' methods are shown to
have good energy conservation in long simulations.Comment: 9 pages, 5 figure
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