591 research outputs found
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Single-jet inclusive rates with exact color at O (αs4)
Next-to-next-to-leading order QCD predictions for single-, double- and even
triple-differential distributions of jet events in proton-proton collisions
have recently been obtained using the NNLOjet framework based on antenna
subtraction. These results are an important input for Parton Distribution
Function fits to hadron-collider data. While these calculations include all of
the partonic channels occurring at this order of the perturbative expansion,
they are based on the leading-color approximation in the case of channels
involving quarks and are only exact in color in the pure-gluon channel. In the
present publication, we verify that the sub-leading color effects in the
single-jet inclusive double-differential cross sections are indeed negligible
as far as phenomenological applications are concerned. This is the first
independent and complete calculation for this observable. We also take the
opportunity to discuss the necessary modifications of the sector-improved
residue subtraction scheme that made this work possible
NNLO QCD study of polarised W <sup>+</sup> W <sup>−</sup> production at the LHC
Longitudinal polarisation of the weak bosons is a direct consequence of
Electroweak symmetry breaking mechanism providing an insight into its nature,
and is instrumental in searches for physics beyond the Standard Model. We
perform a polarisation study of the diboson production in the process at NNLO QCD in the fiducial setup inspired by
experimental measurements at ATLAS. This is the first polarisation study at
NNLO. We employ the double-pole approximation framework for the polarised
calculation, and investigate NNLO effects arising in differential
distributions
NNLO QCD corrections to leptonic observables in top-quark pair production and decay
We calculate a comprehensive set of spin correlations and differential
distributions in top-quark pair production and decay to dilepton final states.
This is the first time such a complete study is performed at next-to-next-to
leading order in QCD. Both inclusive and fiducial distributions are presented
and analyzed. Good agreement between NNLO QCD predictions and data is found. We
demonstrate that it is possible to perform high-precision comparisons of
fixed-order calculations with fiducial-level data. Subtleties of the top quark
definition are raised and clarified. Some of those are found to have a very
significant impact on top-quark pair production at absolute threshold
Recommended from our members
NNLO QCD predictions for W+c-jet production at the LHC
We study the production of a W boson in association with a c-jet at the LHC.
We calculate, for the first time, the complete set of NNLO QCD corrections to
the dominant CKM-diagonal contribution to this process. Both signatures, and are considered. We present predictions for
fiducial cross sections and differential distributions for each one of the two
signatures as well as for their ratio. The theoretical predictions are compared
with ATLAS measurements at . The results of this work are
essential for the precision description of associated heavy flavor production
at hadron colliders and for the determination of the strange-quark content of
the proton from LHC data in NNLO QCD
Recommended from our members
B-hadron production in NNLO QCD: application to LHC t t¯ events with leptonic decays
We calculate, for the first time, the NNLO QCD corrections to identified
heavy hadron production at hadron colliders. The calculation is based on a
flexible numeric framework which allows the calculation of any distribution of
a single identified heavy hadron plus jets and non-QCD particles. As a first
application we provide NNLO QCD predictions for several differential
distributions of hadrons in events at the LHC. Among others,
these predictions are needed for the precise determination of the top quark
mass. The extension of our results to other processes, like open or associated
and charm production is straightforward. We also explore the prospects for
extracting heavy flavor fragmentation functions from LHC data
Two-loop leading-color helicity amplitudes for three-photon production at the LHC
We calculate all planar contributions to the two-loop massless helicity
amplitudes for the process . The results are
presented in fully analytic form in terms of the functional basis proposed
recently by Chicherin and Sotnikov. With this publication we provide the
two-loop contributions already used by us in the NNLO QCD calculation of the
LHC process [Chawdhry et al. (2019)]. Our results
agree with a recent calculation of the same amplitude [Abreu et al. (2020)]
which was performed using different techniques. We combine several modern
computational techniques, notably, analytic solutions for the IBP identities,
finite-field reconstruction techniques as well as the recent approach [Chen
(2019)] for efficiently projecting helicity amplitudes. Our framework appears
well-suited for the calculation of two-loop multileg amplitudes for which
complete sets of master integrals exist
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Proprietary, standard, and government-supported nuclear data bases
B-hadron production in NNLO QCD: application to LHC t t¯ events with leptonic decays
We calculate, for the first time, the NNLO QCD corrections to identified
heavy hadron production at hadron colliders. The calculation is based on a
flexible numeric framework which allows the calculation of any distribution of
a single identified heavy hadron plus jets and non-QCD particles. As a first
application we provide NNLO QCD predictions for several differential
distributions of hadrons in events at the LHC. Among others,
these predictions are needed for the precise determination of the top quark
mass. The extension of our results to other processes, like open or associated
and charm production is straightforward. We also explore the prospects for
extracting heavy flavor fragmentation functions from LHC data
Two-loop leading-colour QCD helicity amplitudes for two-photon plus jet production at the LHC
We calculate the complete set of two-loop leading-colour QCD helicity
amplitudes for -production at hadron colliders. Our results
are presented in a compact, fully-analytical form
NNLO QCD corrections to three-photon production at the LHC
We compute the NNLO QCD corrections to three-photon production at the LHC.
This is the first NNLO QCD calculation for a process. Our calculation
is exact, except for the scale-independent part of the two-loop finite
remainder which is included in the leading color approximation. We estimate the
size of the missing two-loop corrections and find them to be phenomenologically
negligible. We compare our predictions with available 8 TeV measurement from
the ATLAS collaboration. We find that the inclusion of the NNLO corrections
eliminates the existing significant discrepancy with respect to NLO QCD
predictions, paving the way for precision phenomenology in this process
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