1,230 research outputs found
Double real radiation corrections to gluon scattering at NNLO
We use the antenna subtraction method to isolate the double real radiation
infrared singularities present in the six-gluon tree-level process at
next-to-next-to-leading order. We show numerically that the subtraction term
correctly approximates the matrix elements in the various single and double
unresolved configurations.Comment: six pages, talk given at 10th DESY Workshop on Elementary Particle
Theory, Worlitz, 25-30 April 201
Subtraction method of computing QCD jet cross sections at NNLO accuracy
We present a general subtraction method for computing radiative corrections
to QCD jet cross sections at next-to-next-to-leading order accuracy. The steps
needed to set up this subtraction scheme are the same as those used in
next-to-leading order computations. However, all steps need non-trivial
modifications, which we implement such that that those can be defined at any
order in perturbation theory. We give a status report of the implementation of
the method to computing jet cross sections in electron-positron annihilation at
the next-to-next-to-leading order accuracy.Comment: 6 pages, talk given at the conference "Loops and Legs in Quantum
Field Theory", Sondershausen, April 200
Antenna subtraction with hadronic initial states
The antenna subtraction method for the computation of higher order
corrections to jet observables and exclusive cross sections at collider
experiments is extended to include hadronic initial states. In addition to the
already known antenna subtraction with both radiators in the final state
(final-final antennae), we introduce antenna subtractions with one or two
radiators in the initial state (initial-final or initial-initial antennae). For
those, we derive the phase space factorization and discuss the allowed phase
space mappings at NLO and NNLO. We present integrated forms for all antenna
functions relevant to NLO calculations, and describe the construction of the
full antenna subtraction terms at NLO on two examples. The extension of the
formalism to NNLO is outlined.Comment: 33 pages, 3 figure
The infrared structure of e+ e- --> 3 jets at NNLO reloaded
This paper gives detailed information on the structure of the infrared
singularities for the process e+ e- --> 3 jets at next-to-next-to-leading order
in perturbation theory. Particular emphasis is put on singularities associated
to soft gluons. The knowledge of the singularity structure allows the
construction of appropriate subtraction terms, which in turn can be implemented
into a numerical Monte Carlo program.Comment: 59 pages, additional comments added, version to be publishe
Progress on NNLO subtraction
We review standard subtraction, as a method to compute cross sections at NNLO
accuracy.Comment: 6 pages, to appear in the proceedings of the 7th International
Symposium on Radiative Corrections (RADCOR05), Shonan Village, Japan, 200
A novel subtraction scheme for double-real radiation at NNLO
A general subtraction scheme, STRIPPER (SecToR Improved Phase sPacE for real
Radiation), is derived for the evaluation of next-to-next-to-leading order
(NNLO) QCD contributions from double-real radiation to processes with at least
two particles in the final state at leading order. The result is a Laurent
expansion in the parameter of dimensional regularization, the coefficients of
which should be evaluated by numerical Monte Carlo integration. The two main
ideas are a two-level decomposition of the phase space, the second one
factorizing the singular limits of amplitudes, and a suitable parameterization
of the kinematics allowing for derivation of subtraction and integrated
subtraction terms from eikonal factors and splitting functions without
non-trivial analytic integration.Comment: 14 pages, 3 figures, matches published version, includes new name for
the scheme, extended discussion of massless final states, and some new
reference
W boson production at hadron colliders: the lepton charge asymmetry in NNLO QCD
We consider the production of W bosons in hadron collisions, and the
subsequent leptonic decay W->lnu_l. We study the asymmetry between the rapidity
distributions of the charged leptons, and we present its computation up to the
next-to-next-to-leading order (NNLO) in QCD perturbation theory. Our
calculation includes the dependence on the lepton kinematical cuts that are
necessarily applied to select W-> lnu_l events in actual experimental analyses
at hadron colliders. We illustrate the main differences between the W and
lepton charge asymmetry, and we discuss their physical origin and the effect of
the QCD radiative corrections. We show detailed numerical results on the charge
asymmetry in ppbar collisions at the Tevatron, and we discuss the comparison
with some of the available data. Some illustrative results on the lepton charge
asymmetry in pp collisions at LHC energies are presented.Comment: 37 pages, 21 figure
Application of new probabilistic graphical models in the genetic regulatory networks studies
This paper introduces two new probabilistic graphical models for
reconstruction of genetic regulatory networks using DNA microarray data. One is
an Independence Graph (IG) model with either a forward or a backward search
algorithm and the other one is a Gaussian Network (GN) model with a novel
greedy search method. The performances of both models were evaluated on four
MAPK pathways in yeast and three simulated data sets. Generally, an IG model
provides a sparse graph but a GN model produces a dense graph where more
information about gene-gene interactions is preserved. Additionally, we found
two key limitations in the prediction of genetic regulatory networks using DNA
microarray data, the first is the sufficiency of sample size and the second is
the complexity of network structures may not be captured without additional
data at the protein level. Those limitations are present in all prediction
methods which used only DNA microarray data.Comment: 38 pages, 3 figure
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