11,210 research outputs found
Top-quark production measurements
Recent measurements of top-quark production at hadron colliders are reviewed.
The inclusive top-quark pair production is determined at four centre-of-mass
energies at Tevatron and LHC with experimental uncertainties that are close to
the uncertainties in theoretical calculations at next-to-next-to-leading order
in QCD. Several differential measurements are performed and compared to
simulation. Production of single top quarks is studied in the three different
production channels. Top-quark pair production with neutral and charged vector
bosons has been observed by the LHC experiments. Finally, production of
additional heavy flavour quark pairs (, ) is studied or
searched for.Comment: on behalf of the ATLAS, CDF, CMS, D0 and LHCb Collaborations.
Conference proceedings for Lepton Photon, Ljubljana, 17-22 August 2015, 21
pages, 18 figure
The PDF4LHC report on PDFs and LHC data: Results from Run I and preparation for Run II
The accurate determination of the Parton Distribution Functions (PDFs) of the
proton is an essential ingredient of the Large Hadron Collider (LHC) program.
PDF uncertainties impact a wide range of processes, from Higgs boson
characterisation and precision Standard Model measurements to New Physics
searches. A major recent development in modern PDF analyses has been to exploit
the wealth of new information contained in precision measurements from the LHC
Run I, as well as progress in tools and methods to include these data in PDF
fits. In this report we summarise the information that PDF-sensitive
measurements at the LHC have provided so far, and review the prospects for
further constraining PDFs with data from the recently started Run II. This
document aims to provide useful input to the LHC collaborations to prioritise
their PDF-sensitive measurements at Run II, as well as a comprehensive
reference for the PDF-fitting collaborations.Comment: 55 pages, 13 figure
TOP2017: Experimental Summary
At the time of the 10th International Workshop on Top Quark Physics
(TOP2017), top quark physics is a very dynamic research area. Thanks to the
unprecedentedly fast accumulation of high-energy data at the LHC during the
ongoing Run~2, statistical starvation is a matter of the past for most of the
traditional top-quark analyses, that are now experiencing the luxury of having
to worry about how to punch through the "Systematics Wall" and maximize the
utility of their data. New processes involving top quarks are being studied for
the first time, and the good old pair-production processes are being explored
in unusual settings, such as collisions involving heavy ions, or "reference
data" collected by the LHC at relatively low centre-of-mass energy. The TOP2017
conference featured 37 talks delivered by experimental physicists, including
seven in the "Young Scientists Forum" where young colleagues were given the
opportunity to elaborate more deeply than usual on their own work. As it is
impossible to do justice to all the experimental results presented at this
conference while staying within a reasonable length, this document contains a
very biased selection, mostly based on the personal taste of the author.Comment: Proceedings of the 10th International Workshop on Top Quark Physics,
Braga, Portugal, September 17-22, 201
Top-Quark Physics at the LHC
The top quark is the heaviest of all known elementary particles. It was
discovered in 1995 by the CDF and D0 experiments at the Tevatron. With the
start of the LHC in 2009, an unprecedented wealth of measurements of the top
quark's production mechanisms and properties have been performed by the ATLAS
and CMS collaborations, most of these resulting in smaller uncertainties than
those achieved previously. At the same time, huge progress was made on the
theoretical side yielding significantly improved predictions up to
next-to-next-to-leading order in perturbative QCD. Due to the vast amount of
events containing top quarks, a variety of new measurements became feasible and
opened a new window to precisions tests of the Standard Model and to
contributions of new physics. In this review, originally written for a recent
book on the results of LHC Run 1, top-quark measurements obtained so far from
the LHC Run 1 are summarised and put in context with the current understanding
of the Standard Model.Comment: 35 pages, 25 figures. To appear in "The Large Hadron Collider --
Harvest of Run 1", Thomas Sch\"orner-Sadenius (ed.), Springer, 2015 (532
pages, 253 figures; ISBN 978-3-319-15000-0; eBook ISBN 978-3-319-15001-7, for
more details, see http://www.springer.com/de/book/9783319150000
DIS2015 Heavy Flavours Working Group Summary
Studies presented in the heavy flavours working group are summarized. Very
recent results of measurements at the HERA, LHC, Tevatron, STAR, PHENIX, and
BaBar experiments are reviewed and new developments in theory and phenomenology
are discussed. In particular, aspects of the impact of heavy flavours on global
QCD analyses to determine the structure of the proton, and analyses in physics
beyond the Standard Model are considered.Comment: 16 pages, 16 figures, Conference proceeding summary, DIS2015 "The
XXIII International Workshop on Deep Inelastic Scattering and Related
Subjects", April 27 - May 1, 2015, Southern Methodist University, Dallas,
Texas, US
Top-quark physics at the Large Hadron Collider
This experimental review gives an overview of top-quark measurements
performed by the two general purpose-detectors ATLAS and CMS during the first
few years of running of the Large Hadron Collider. In the years 2010 - 2012
each experiment collected 5 fb of pp collision data at
TeV and 20 fb at TeV, allowing detailed studies of
top-quark production and decays, and measurements of the properties of the top
quark with unprecedented precision.Comment: 54 pages, 42 figures, 2 tables. Accepted for publication in J. Phys.
Top-quark pair production at hadron colliders: differential cross section and phenomenological applications with DiffTop
The results of phenomenological studies of top-quark pair production in
proton-proton collisions are presented. Differential cross sections are
calculated in perturbative QCD at approximate next-to-next-to-leading order
by using methods of threshold resummation beyond the
leading logarithmic accuracy. Predictions for the single-particle inclusive
kinematics are presented for transverse momentum and rapidity distributions of
final-state top quarks. Uncertainties related to the description of proton
structure, top-quark mass and strong coupling constant are investigated in
detail. The results are compared to the recent measurements by the ATLAS and
CMS collaborations at the LHC at the center of mass energy of 7 TeV. The
calculation presented here is implemented in the computer code \textsc{Difftop}
and can be applied to the general case of heavy-quark pair production at
hadron-hadron colliders. For the first time, a fit of parton distribution
functions at NNLO is performed by using the differential cross sections of
top-quark pair production together with other data sets. The impact of the
top-pair production on the precision of the gluon distribution at high scales
is illustrated.Comment: 30 pages, 12 figures, 2 tables, regular article. Version accepted for
a publication on JHE
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