924 research outputs found
One Loop Multiphoton Helicity Amplitudes
We use the solutions to the recursion relations for double-off-shell fermion
currents to compute helicity amplitudes for -photon scattering and
electron-positron annihilation to photons in the massless limit of QED. The
form of these solutions is simple enough to allow {\it all}\ of the
integrations to be performed explicitly. For -photon scattering, we find
that unless , the amplitudes for the helicity configurations (+++...+) and
(-++...+) vanish to one-loop order.Comment: 27 pages + 4 uuencoded figures (included), Fermilab-Pub-93/327-T,
RevTe
BES3 time of flight monitoring system
A Time of Flight monitoring system has been developed for BES3.
The light source is a 442-443 nm laser diode, which is stable and provides a
pulse width as narrow as 50 ps and a peak power as large as 2.6 W. Two
optical-fiber bundles with a total of 512 optical fibers, including spares, are
used to distribute the light pulses to the Time of Flight counters. The design,
operation, and performance of the system are described.Comment: 8 pages 16 figures, submitted to NI
Explicit Renormalization Group for D=2 random bond Ising model with long-range correlated disorder
We investigate the explicit renormalization group for fermionic field
theoretic representation of two-dimensional random bond Ising model with
long-range correlated disorder. We show that a new fixed point appears by
introducing a long-range correlated disorder. Such as the one has been observed
in previous works for the bosonic () description. We have calculated
the correlation length exponent and the anomalous scaling dimension of
fermionic fields at this fixed point. Our results are in agreement with the
extended Harris criterion derived by Weinrib and Halperin.Comment: 5 page
Prospects of Open Charm Production at GSI-FAIR and J-PARC
We present a detailed phenomenological study of the prospects of open charm
physics at the future and facilities GSI-FAIR and J-PARC,
respectively. In particular, we concentrate on differential cross sections and
the charge and longitudinal double-spin asymmetries at next-to-leading order
accuracy. Theoretical uncertainties for the proposed observables are estimated
by varying the charm quark mass and the renormalization and factorization
scales.Comment: 11 pages, 13 figure
Radiative corrections to the Casimir effect for the massive scalar field
We compute the correction to the Casimir energy for the massive
model confined between a pair of parallel plates. The
calculations are made with Dirichlet and Neumann boundary conditions. The
correction is shown to be sensitive to the boundary conditions, except in the
zero mass limit, in which case our results agree with those found in the
literature.Comment: 6 pages. Work presented at the XXIII Brazilian National Meeting on
Particles and Fields (Aguas de Lindoia, Brazil, 15-19 Oct 2002). Also
available at http://www.sbf1.if.usp.br/eventos/enfpc/xxiii/procs/RES142.pd
Comparison between variable flavor number schemes for charm quark electroproduction
Where appropriate, the abbreviation 'VFNS' is replaced by 'CSN' to indicate
the scheme using massive heavy quark coefficient functions proposed in this
paper. The text below Eq. (2.13) and between Eqs. (2.33) and (2.36) has been
considerably changed.Comment: 64 pages, LaTeX, 16 Postscript figure
Monte-Carlo Generator Photon Jets for the process e+e- -> gamma gamma
Monte-Carlo generator with photon jets radiation in collinear regions for the
process \eegg is described in detail. Radiative corrections in the first order
of are treated exactly. Large leading logarithmic corrections coming
from collinear regions are taken into account in all orders of by
applying the Structure Function approach. Theoretical precision of the cross
section with radiative corrections is estimated to be 0.2%. This process is
considered as an additional tool to measure luminosity in forthcoming
experiments with the CMD-3 detector at the collider VEPP-2000.Comment: 6 pages, 5 figure
Next-to-Leading Order Cross Sections for Tagged Reactions
We extend the phase space slicing method of Giele, Glover and Kosower for
performing next-to-leading order jet cross section calculations in two
important ways: we show how to include fragmentation functions and how to
include massive particles. These extensions allow the application of this
method to not just jet cross sections but also to cross sections in which a
particular final state particle, including a or -meson, is tagged.Comment: 36 pages, Latex Small corrections to text. To appear in Phys. Rev.
Radiative Corrections to One-Photon Decays of Hydrogenic Ions
Radiative corrections to the decay rate of n=2 states of hydrogenic ions are
calculated. The transitions considered are the M1 decay of the 2s state to the
ground state and the E1(M2) decays of the and states to
the ground state. The radiative corrections start in order , but the method used sums all orders of . The leading
correction for the E1 decays is calculated and compared
with the exact result. The extension of the calculational method to parity
nonconserving transitions in neutral atoms is discussed.Comment: 22 pages, 2 figure
Evaluating the potential drilling success of exploration programmes using a three-dimensional geological model - a case study
The technological advancements in computing power in the last 30 years have enabled the practical
visualization of complex geological environments in three-dimensional (3D) space. 3D models and their
application in the mining industry are becoming increasingly important, for example, to identify future
exploration areas and targets, for mineral assessment and evaluation, and prediction and planning of
future drill-holes. However, acquiring borehole data is an expensive practice, with drilling programmes
costing mining companies up to billions of dollars each year. Tighter financial constraints on exploration
budgets result in more pressure being put on three-dimensional models to accurately identify future
target areas. This article aims to evaluate the potential drilling success of simulated greenfield and
brownfield exploration using a 3D geological model created of Leeuwpoort tin mine. These simulations
investigate the probability of intersecting a mineralized zone of economic interest and evaluate how the
probability is affected when the number of drill-holes and distance from a known intersection changes.
Furthermore, these simulations attempt to obtain an indication for the minimum number of drill-holes
required for a successful exploration campaign at the mine. The investigation also aims to establish
a first-pass attempt towards developing a âfavoured procedureâ for identifying potential exploration
targets for tin deposits with geological and geochemical characteristics similar to Leeuwpoort. The
results for the âfavoured procedureâ established are statistically tested using the âbootstrappingâ method.
By simulating various exploration scenarios, the study also emphasises the importance of predicting
successful drilling, which aids in budgeting for drilling programmes as the minimum number of drillholes
needed for a specific exploration project can be determined.https://journals.co.za/journal/saimmam2023Geolog
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