779 research outputs found
The Dipole Formalism for the Calculation of QCD Jet Cross Sections at Next-to-Leading Order
In order to make quantitative predictions for jet cross sections in
perturbative QCD, it is essential to calculate them to next-to-leading
accuracy. This has traditionally been an extremely laborious process. Using a
new formalism, imaginatively called the dipole formalism, we are able to
construct a completely general algorithm for next-to-leading order calculations
of arbitrary jet quantities in arbitrary processes. In this paper we present
the basic ideas behind the algorithm and illustrate them with a simple example.Comment: 17 pages, 2 figures. A postscript version of this paper can be
obtained from http://surya11.cern.ch/users/seymour/pubs/nlolett.ps.Z .
Reposted version corrects several misprint
Langdurige bewaring van kroten in een geventileerde kuil en in een mechanisch gekoelde cel in seizoen 1986 - 1987, 1987 - 1988 en 1988 - 1989
Lange bewaring van kroten in een geventileerde kuil en een vergelijking met lange bewaring in een mechanisch gekoelde cel = Long term bulk storage of red beets in forced ventilated clamps in comparison with long term storage in mechanical cooling
Bond-disordered Anderson model on a two dimensional square lattice - chiral symmetry and restoration of one-parameter scaling
Bond-disordered Anderson model in two dimensions on a square lattice is
studied numerically near the band center by calculating density of states
(DoS), multifractal properties of eigenstates and the localization length. DoS
divergence at the band center is studied and compared with Gade's result [Nucl.
Phys. B 398, 499 (1993)] and the powerlaw. Although Gade's form describes
accurately DoS of finite size systems near the band-center, it fails to
describe the calculated part of DoS of the infinite system, and a new
expression is proposed. Study of the level spacing distributions reveals that
the state closest to the band center and the next one have different level
spacing distribution than the pairs of states away from the band center.
Multifractal properties of finite systems furthermore show that scaling of
eigenstates changes discontinuously near the band center. This unusual behavior
suggests the existence of a new divergent length scale, whose existence is
explained as the finite size manifestation of the band center critical point of
the infinite system, and the critical exponent of the correlation length is
calculated by a finite size scaling. Furthermore, study of scaling of Lyapunov
exponents of transfer matrices of long stripes indicates that for a long stripe
of any width there is an energy region around band center within which the
Lyapunov exponents cannot be described by one-parameter scaling. This region,
however, vanishes in the limit of the infinite square lattice when
one-parameter scaling is restored, and the scaling exponent calculated, in
agreement with the result of the finite size scaling analysis.Comment: 23 pages, 11 figures. RevTe
A Micro-Costing Framework for Circulating Tumor DNA Testing in Dutch Clinical Practice
Circulating tumor DNA (ctDNA) is a promising new biomarker with multiple potential applications in cancer care. Estimating total cost of ctDNA testing is necessary for reimbursement and implementation, but challenging because of variations in workflow. We aimed to develop a micro-costing framework for consistent cost calculation of ctDNA testing. First, the foundation of the framework was built, based on the complete step-wise diagnostic workflow of ctDNA testing. Second, the costing method was set up, including costs for personnel, materials, equipment, overhead, and failures. Third, the framework was evaluated by experts and applied to six case studies, including PCR-, mass spectrometry–, and next-generation sequencing–based platforms, from three Dutch hospitals. The developed ctDNA micro-costing framework includes the diagnostic workflow from blood sample collection to diagnostic test result. The framework was developed from a Dutch perspective and takes testing volume into account. An open access tool is provided to allow for laboratory-specific calculations to explore the total costs of ctDNA testing specific workflow parameters matching the setting of interest. It also allows to straightforwardly assess the impact of alternative prices or assumptions on the cost per sample by simply varying the input parameters. The case studies showed a wide range of costs, from €168 to €7638 (9124) per sample, and generated information. These costs are sensitive to the (coverage of) platform, setting, and testing volume
Charge Transport Through Open, Driven Two-Level Systems with Dissipation
We derive a Floquet-like formalism to calculate the stationary average
current through an AC driven double quantum dot in presence of dissipation. The
method allows us to take into account arbitrary coupling strengths both of a
time-dependent field and a bosonic environment. We numerical evaluate a
truncation scheme and compare with analytical, perturbative results such as the
Tien-Gordon formula.Comment: 14 pages, 6 figures. To appear in Phys. Rev.
Hadronic final states in deep-inelastic scattering with Sherpa
We extend the multi-purpose Monte-Carlo event generator Sherpa to include
processes in deeply inelastic lepton-nucleon scattering. Hadronic final states
in this kinematical setting are characterised by the presence of multiple
kinematical scales, which were up to now accounted for only by specific
resummations in individual kinematical regions. Using an extension of the
recently introduced method for merging truncated parton showers with
higher-order tree-level matrix elements, it is possible to obtain predictions
which are reliable in all kinematical limits. Different hadronic final states,
defined by jets or individual hadrons, in deep-inelastic scattering are
analysed and the corresponding results are compared to HERA data. The various
sources of theoretical uncertainties of the approach are discussed and
quantified. The extension to deeply inelastic processes provides the
opportunity to validate the merging of matrix elements and parton showers in
multi-scale kinematics inaccessible in other collider environments. It also
allows to use HERA data on hadronic final states in the tuning of hadronisation
models.Comment: 32 pages, 22 figure
Phenomenology of the Lense-Thirring effect in the Solar System
Recent years have seen increasing efforts to directly measure some aspects of
the general relativistic gravitomagnetic interaction in several astronomical
scenarios in the solar system. After briefly overviewing the concept of
gravitomagnetism from a theoretical point of view, we review the performed or
proposed attempts to detect the Lense-Thirring effect affecting the orbital
motions of natural and artificial bodies in the gravitational fields of the
Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of
the impact of several sources of systematic uncertainties of dynamical origin
to realistically elucidate the present and future perspectives in directly
measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in
Astrophysics and Space Science (ApSS). Some uncited references in the text
now correctly quoted. One reference added. A footnote adde
A General Algorithm for Calculating Jet Cross Sections in NLO QCD
We present a new general algorithm for calculating arbitrary jet cross
sections in arbitrary scattering processes to next-to-leading accuracy in
perturbative QCD. The algorithm is based on the subtraction method. The key
ingredients are new factorization formulae, called dipole formulae, which
implement in a Lorentz covariant way both the usual soft and collinear
approximations, smoothly interpolating the two. The corresponding dipole phase
space obeys exact factorization, so that the dipole contributions to the cross
section can be exactly integrated analytically over the whole of phase space.
We obtain explicit analytic results for any jet observable in any scattering or
fragmentation process in lepton, lepton-hadron or hadron-hadron collisions. All
the analytical formulae necessary to construct a numerical program for
next-to-leading order QCD calculations are provided. The algorithm is
straightforwardly implementable in general purpose Monte Carlo programs.Comment: Resubmitted version corrects an error in the definitions of the
Lorentz boosts used in sections 5.5 and 5.6. No other results are affected.
120 pages, 4 figures. This paper can also be obtained from
http://surya11.cern.ch/users/seymour/pubs/nlo.htm
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