379 research outputs found
Multiple photon corrections to the neutral-current Drell-Yan process
Precision studies of single W and Z production processes at hadron colliders
require progress in the calculation of electroweak radiative corrections. To
this end, higher-order QED corrections to the neutral-current Drell-Yan
process, due to multiple photon radiation in Z leptonic decays, are calculated.
Particular attention is paid to the effects induced by such corrections on the
experimental observables which are relevant for high-precision measurements of
the W-boson mass at the Tevatron Run II and the LHC. The calculation is
implemented in the Monte Carlo event generator HORACE, which is available for
data analysis.Comment: 16 pages, 4 figures, 3 tables, JHEP3 styl
Osteoma Cutis Associated with Nevus Sebaceus: Case Report and Review of Cutaneous Osteoma-associated Skin Tumors (COASTs)
Osteoma cutis is a benign cutaneous lesion characterized by the presence of bone within the dermis or subcutaneous fat. It most often develops in association with other skin lesions such as cutaneous tumors. Nevus sebaceus is a benign hamartoma of the skin that is composed of epidermal and dermal components. It most commonly appears on the scalp and may give rise to either benign or malignant secondary neoplasms. The clinical and pathologic features of a 36-year-old man with a nevus sebaceus and associated osteoma cutis are described. In addition, osteoma cutis-associated neoplasms are reviewed. Secondary osteoma cutis has been observed with both benign and malignant neoplasms as well as various non-neoplastic skin conditions. However, to the best of our knowledge, osteoma cutis has not previously been described in association with nevus sebaceus. Nevus sebaceus can now be added to the list of cutaneous osteoma-associated skin tumors (COASTs)
Controlled formation of metallic nanowires via Au nanoparticle ac trapping
Applying ac voltages, we trapped gold nanoparticles between microfabricated
electrodes under well-defined conditions. We demonstrate that the nanoparticles
can be controllably fused together to form homogeneous gold nanowires with
pre-defined diameters and conductance values. Whereas electromigration is known
to form a gap when a dc voltage is applied, this ac technique achieves the
opposite, thereby completing the toolkit for the fabrication of nanoscale
junctions.Comment: Nanotechnology 18, 235202 (2007
Surface Plasmon Enhanced Photoconductance of Gold Nanoparticle Arrays with Incorporated Alkane Linkers
We report on a photoconductive gain effect in two-dimensional arrays of gold
nanoparticles, in which alkane molecules are inserted. The nanoparticle arrays
are formed by a self-assembly process from alkanethiol-coated gold
nanoparticles, and subsequently they are patterned on a Si/SiO2 chip by a
microcontact printing technique. We find that the photoconductance of the
arrays is strongly enhanced at the frequency of the surface plasmon of the
nanoparticles. We interpret the observation as a bolometric enhancement of the
conductance of the nanoparticle arrays upon excitation of the surface plasmon
resonance
Combination of electroweak and QCD corrections to single W production at the Fermilab Tevatron and the CERN LHC
Precision studies of the production of a high-transverse momentum lepton in
association with missing energy at hadron colliders require that electroweak
and QCD higher-order contributions are simultaneously taken into account in
theoretical predictions and data analysis. Here we present a detailed
phenomenological study of the impact of electroweak and strong contributions,
as well as of their combination, to all the observables relevant for the
various facets of the p\smartpap \to {\rm lepton} + X physics programme at
hadron colliders, including luminosity monitoring and Parton Distribution
Functions constraint, precision physics and search for new physics signals.
We provide a theoretical recipe to carefully combine electroweak and strong
corrections, that are mandatory in view of the challenging experimental
accuracy already reached at the Fermilab Tevatron and aimed at the CERN LHC,
and discuss the uncertainty inherent the combination. We conclude that the
theoretical accuracy of our calculation can be conservatively estimated to be
about 2% for standard event selections at the Tevatron and the LHC, and about
5% in the very high transverse mass/lepton transverse momentum tails. We
also provide arguments for a more aggressive error estimate (about 1% and 3%,
respectively) and conclude that in order to attain a one per cent accuracy: 1)
exact mixed corrections should be computed in
addition to the already available NNLO QCD contributions and two-loop
electroweak Sudakov logarithms; 2) QCD and electroweak corrections should be
coherently included into a single event generator.Comment: One reference added. Final version to appear in JHE
Results on Multiple Coulomb Scattering from 12 and 20 GeV electrons on Carbon targets
Multiple scattering effects of 12 and 20 GeV electrons on 8 and 20 mm
thickness carbon targets have been studied with high-resolution silicon
microstrip detectors of the UA9 apparatus at the H8 line at CERN. Comparison of
the scattering angle between data and GEANT4 simulation shows excellent
agreement in the core of the distributions leaving some residual disagreement
in the tails.Comment: 14 pages, 16 figures. Updated to match published versio
Fluctuation-dissipation theorem and flux noise in overdamped Josephson junction arrays
The form of the fluctuation-dissipation theorem for a resistively shunted
Josephson juction array is derived with the help of the method which
explicitely takes into acoount screening effects. This result is used to
express the flux noise power spectrum in terms of frequency dependent sheet
impedance of the array. The relation between noise amplitude and parameters of
the detection coil is analysed for the simplest case of a single-loop coil.Comment: ReVTeX, 8 page
Aging and memory phenomena in magnetic and transport properties of vortex matter: a brief review
There is mounting experimental evidence that strong off-equilibrium
phenomena, such as ``memory'' or ``aging'' effects, play a crucial role in the
physics of vortices in type II superconductors. We give a short review, based
on a recently introduced schematic vortex model, of current progresses in
understanding out of equilibrium vortex behaviours. We develop a unified
description of ``memory'' phenomena in magnetic and transport properties, such
as magnetisation loops and their ``anomalous'' 2nd peak, logarithmic creep,
``anomalous'' finite creep rate in the limit of vanishing temperature,
``memory'' and ``irreversibility'' in I-V characteristics, time dependent
critical currents, ``rejuvenation'' and ``aging'' of the system response.Comment: updated versio
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