62 research outputs found
Implementation of electroweak corrections in the POWHEG BOX: single W production
We present a fully consistent implementation of electroweak and strong
radiative corrections to single W hadroproduction in the POWHEG BOX framework,
treating soft and collinear photon emissions on the same ground as coloured
parton emissions. This framework can be easily extended to more complex
electroweak processes. We describe how next-to-leading order (NLO) electroweak
corrections are combined with the NLO QCD calculation, and show how they are
interfaced to QCD and QED shower Monte Carlo. The resulting tool fills a gap in
the literature and allows to study comprehensively the interplay of QCD and
electroweak effects to W production using a single computational framework.
Numerical comparisons with the predictions of the electroweak generator HORACE,
as well as with existing results on the combination of electroweak and QCD
corrections to W production, are shown for the LHC energies, to validate the
reliability and accuracy of the approachComment: 31 pages, 7 figures. Minor corrections, references added and updated.
Final version to appear in JHE
Antenna subtraction with massive fermions at NNLO: Double real initial-final configurations
We derive the integrated forms of specific initial-final tree-level
four-parton antenna functions involving a massless initial-state parton and a
massive final-state fermion as hard radiators. These antennae are needed in the
subtraction terms required to evaluate the double real corrections to
hadronic production at the NNLO level stemming from the partonic
processes and .Comment: 24 pages, 1 figure, 1 Mathematica file attache
Antenna subtraction for gluon scattering at NNLO
We use the antenna subtraction method to isolate the double real radiation
infrared singularities present in gluonic scattering amplitudes at
next-to-next-to-leading order. The antenna subtraction framework has been
successfully applied to the calculation of NNLO corrections to the 3-jet cross
section and related event shape distributions in electron-positron
annihilation. Here we consider processes with two coloured particles in the
initial state, and in particular two-jet production at hadron colliders such as
the Large Hadron Collider (LHC). We construct a subtraction term that describes
the single and double unresolved contributions from the six-gluon tree-level
process using antenna functions with initial state partons and show numerically
that the subtraction term correctly approximates the matrix elements in the
various single and double unresolved configurations.Comment: 71 pages, JHEP3 class; corrected typos, equivalent but more compact
version of eq. (5.12), results unchange
Regularization-scheme dependence of QCD amplitudes in the massive case
We investigate QCD amplitudes with massive quarks computed in the four-dimensional helicity scheme (FDH) and dimensional reduction at NNLO and describe how they are related to the corresponding amplitudes computed in conventional dimensional regularization. To this end, the scheme dependence of the heavy quark and the velocity-dependent cusp anomalous dimensions is determined using soft-collinear effective theory. The results are checked against explicit computations of massive form factors in FDH at NNLO. Our results complete the description of the scheme dependence of QCD amplitudes at NNLO
Age-Related Memory Impairment Is Associated with Disrupted Multivariate Epigenetic Coordination in the Hippocampus
Mounting evidence linking epigenetic regulation to memory-related synaptic plasticity raises the possibility that altered chromatin modification dynamics might contribute to age-dependent cognitive decline. Here we show that the coordinated orchestration of both baseline and experience-dependent epigenetic regulation seen in the young adult hippocampus is lost in association with cognitive aging. Using a well-characterized rat model that reliably distinguishes aged individuals with significant memory impairment from others with normal memory, no single epigenetic mark or experience-dependent modification in the hippocampus uniquely predicted differences in the cognitive outcome of aging. The results instead point to a multivariate pattern in which modification-specific, bidirectional chromatin regulation is dependent on recent behavioral experience, chronological age, cognitive status, and hippocampal region. Whereas many epigenetic signatures were coupled with memory capacity among young adults and aged rats with preserved cognitive function, such associations were absent among aged rats with deficits in hippocampal memory. By comparison with the emphasis in current preclinical translational research on promoting chromatin modifications permissive for gene expression, our findings suggest that optimally successful hippocampal aging may hinge instead on enabling coordinated control across the epigenetic landscape
Higgs boson gluon-fusion production beyond threshold in N3LO QCD
In this article, we compute the gluon fusion Higgs boson cross-section at
N3LO through the second term in the threshold expansion. This calculation
constitutes a major milestone towards the full N3LO cross section. Our result
has the best formal accuracy in the threshold expansion currently available,
and includes contributions from collinear regions besides subleading
corrections from soft and hard regions, as well as certain logarithmically
enhanced contributions for general kinematics. We use our results to perform a
critical appraisal of the validity of the threshold approximation at N3LO in
perturbative QCD
Forty years literature review of primary lung lymphoma
There are several unresolved issues through out the literature regarding the entity of primary lung lymphoma. Extensive literature review of this uncommon pathology is carried out
Antenna subtraction at NNLO with hadronic initial states: real-virtual initial-initial configurations
The antenna subtraction method handles real radiation contributions in higher
order corrections to jet observables. The method is based on antenna functions,
which encapsulate all unresolved radiation between a pair of hard radiator
partons. To apply this method to compute hadron collider observables,
initial-initial antenna functions with both radiators in the initial state are
required. In view of extending the antenna subtraction method to
next-to-next-to-leading order (NNLO) calculations at hadron colliders, we
derive the one-loop initial-initial antenna functions in unintegrated and
integrated form.Comment: 24 page
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