scholarly journals Determination of the parton distribution functions of the proton from ATLAS measurements of differential W± and Z boson production in association with jets

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
◽  
G. Aad ◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Z Boson ◽  
Parton Distribution ◽  
Distribution Functions ◽  
Scattering Data ◽  
Boson Production ◽  
Data Sets ◽  
Parton Distribution Functions ◽  
Deep Inelastic Scattering Data ◽  
8 Tev

Abstract This article presents a new set of proton parton distribution functions, ATLASepWZVjet20, produced in an analysis at next-to-next-to-leading order in QCD. The new data sets considered are the measurements of W+ and W− boson and Z boson production in association with jets in pp collisions at $$ \sqrt{s} $$ s = 8 TeV performed by the ATLAS experiment at the LHC with integrated luminosities of 20.2 fb−1 and 19.9 fb−1, respectively. The analysis also considers the ATLAS measurements of differential W± and Z boson production at $$ \sqrt{s} $$ s = 7 TeV with an integrated luminosity of 4.6 fb−1 and deep-inelastic-scattering data from e±p collisions at the HERA accelerator. An improved determination of the sea-quark densities at high Bjorken x is shown, while confirming a strange-quark density similar in size to the up- and down-sea-quark densities in the range x ≲ 0.02 found by previous ATLAS analyses.

scholarly journals αs from global fits of parton distribution functions

2016 ◽  
Vol 31 (25) ◽  
pp. 1630023 ◽  
Author(s):  
S. Alekhin ◽  
J. Blümlein ◽  
S.-O. Moch
Keyword(s):  
Inelastic Scattering ◽  
Deep Inelastic Scattering ◽  
Parton Distribution ◽  
Distribution Functions ◽  
Scattering Data ◽  
Hard Scattering ◽  
Coupling Constant ◽  
Parton Distribution Functions ◽  
The Status

The status of the determination of the strong coupling constant [Formula: see text] from deep-inelastic scattering and related hard scattering data is reviewed.

scholarly journals Parton distributions from LHC, HERA, Tevatron and fixed target data: MSHT20 PDFs

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
S. Bailey ◽  
T. Cridge ◽  
L. A. Harland-Lang ◽  
A. D. Martin ◽  
R. S. Thorne
Keyword(s):  
Top Quark ◽  
Valence Quark ◽  
Vector Boson ◽  
Distribution Functions ◽  
Scattering Data ◽  
Data Sets ◽  
Parton Distribution Functions ◽  
Inclusive Jets ◽  
Dimuon Production ◽  
8 Tev

AbstractWe present the new MSHT20 set of parton distribution functions (PDFs) of the proton, determined from global analyses of the available hard scattering data. The PDFs are made available at NNLO, NLO, and LO, and supersede the MMHT14 sets. They are obtained using the same basic framework, but the parameterisation is now adapted and extended, and there are 32 pairs of eigenvector PDFs. We also include a large number of new data sets: from the final HERA combined data on total and heavy flavour structure functions, to final Tevatron data, and in particular a significant number of new LHC 7 and 8 TeV data sets on vector boson production, inclusive jets and top quark distributions. We include up to NNLO QCD corrections for all data sets that play a major role in the fit, and NLO EW corrections where relevant. We find that these updates have an important impact on the PDFs, and for the first time the NNLO fit is strongly favoured over the NLO, reflecting the wider range and in particular increased precision of data included in the fit. There are some changes to central values and a significant reduction in the uncertainties of the PDFs in many, though not all, cases. Nonetheless, the PDFs and the resulting predictions are generally within one standard deviation of the MMHT14 results. The major changes are the $$u-d$$ u - d valence quark difference at small x, due to the improved parameterisation and new precise data, the $${\bar{d}}, {\bar{u}}$$ d ¯ , u ¯ difference at small x, due to a much improved parameterisation, and the strange quark PDF due to the effect of LHC W, Z data and inclusion of new NNLO corrections for dimuon production in neutrino DIS. We discuss the phenomenological impact of our results, and in general find reduced uncertainties in predictions for processes such as Higgs, top quark pair and W, Z production at post LHC Run-II energies.

scholarly journals Z-boson production in p-Pb collisions at $$ \sqrt{s_{\mathrm{NN}}} $$ = 8.16 TeV and Pb-Pb collisions at $$ \sqrt{s_{\mathrm{NN}}} $$ = 5.02 TeV

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
S. Acharya ◽  
◽  
D. Adamová ◽  
A. Adler ◽  
J. Adolfsson ◽  
...  
Keyword(s):  
Z Boson ◽  
Decay Channel ◽  
Theoretical Calculations ◽  
Center Of Mass ◽  
Laboratory Frame ◽  
Distribution Functions ◽  
Boson Production ◽  
Free Nucleon ◽  
Parton Distribution Functions ◽  
Nuclear Modifications

Abstract Measurement of Z-boson production in p-Pb collisions at $$ \sqrt{s_{\mathrm{NN}}} $$ s NN = 8.16 TeV and Pb-Pb collisions at $$ \sqrt{s_{\mathrm{NN}}} $$ s NN = 5.02 TeV is reported. It is performed in the dimuon decay channel, through the detection of muons with pseudorapidity −4 < ημ< −2.5 and transverse momentum $$ {p}_{\mathrm{T}}^{\mu } $$ p T μ > 20 GeV/c in the laboratory frame. The invariant yield and nuclear modification factor are measured for opposite-sign dimuons with invariant mass 60 < mμμ< 120 GeV/c2 and rapidity 2.5 <$$ {y}_{\mathrm{cms}}^{\mu \mu} $$ y cms μμ < 4. They are presented as a function of rapidity and, for the Pb-Pb collisions, of centrality as well. The results are compared with theoretical calculations, both with and without nuclear modifications to the Parton Distribution Functions (PDFs). In p-Pb collisions the center-of-mass frame is boosted with respect to the laboratory frame, and the measurements cover the backward (−4.46 <$$ {y}_{\mathrm{cms}}^{\mu \mu} $$ y cms μμ < −2.96) and forward (2.03 <$$ {y}_{\mathrm{cms}}^{\mu \mu} $$ y cms μμ < 3.53) rapidity regions. For the p-Pb collisions, the results are consistent within experimental and theoretical uncertainties with calculations that include both free-nucleon and nuclear-modified PDFs. For the Pb-Pb collisions, a 3.4σ deviation is seen in the integrated yield between the data and calculations based on the free-nucleon PDFs, while good agreement is found once nuclear modifications are considered.

scholarly journals Delineating the Polarized and Unpolarized Parton Structure of the Nucleon

2015 ◽  
Vol 37 ◽  
pp. 1560053
Author(s):  
Pedro Jimenez-Delgado
Keyword(s):  
Parton Distribution ◽  
Distribution Functions ◽  
Distribution Analysis ◽  
Coupling Constant ◽  
Parton Distribution Functions ◽  
Careful Treatment ◽  
Future Data ◽  
The Impact

Reports on our latest extractions of parton distribution functions of the nucleon are given. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are reported, including a careful treatment of hadronic and nuclear corrections, as well as reports on the impact of present and future data in our understanding of the spin of the nucleon.

scholarly journals Study of the Drell-Yan process with the pair-production of polarized tau leptons in collisions of polarized proton beams

2019 ◽  
Vol 222 ◽  
pp. 03021
Author(s):  
A. Aleshko ◽  
E. Boos ◽  
V. Bunichev
Keyword(s):  
Parton Distribution ◽  
Polarization State ◽  
Distribution Functions ◽  
Hadronic Decay ◽  
New Method ◽  
Tau Leptons ◽  
Parton Distribution Functions ◽  
Accuracy Of Measurements ◽  
Polarized Proton

The new method for studying polarized parton distribution functions via the Drell-Yan process with tau production is proposed. The hadronic decay of tau to single charged pi-meson and neutrino is utilised for determination of the polarization state of the tau-lepton. The key feature of our approach is that we do not sum over the polarizations states of tau, but preserve this information through energies ofpions produced in corresponding decays. The new method in addition to existing ones should improve the accuracy of measurements of polarized structure functions of hadrons. In the current work, the feasibility of such an approach is assessed through numerical simulations.

H1 INCLUSIVE CROSS-SECTION MEASUREMENTS AND AN EXTRACTION OF PARTON DISTRIBUTION FUNCTIONS

2005 ◽  
Vol 20 (21) ◽  
pp. 1557-1571
Author(s):  
BURKARD REISERT
Keyword(s):  
Cross Section ◽  
Parton Distribution ◽  
Inclusive Cross Section ◽  
Distribution Functions ◽  
Parton Distribution Functions ◽  
Single Experiment ◽  
Parton Distributions ◽  
The Standard Model ◽  
Qcd Analysis

An extraction of the parton distributions of the proton by a next-to-leading order QCD fit in the framework of the Standard Model is presented. The fit implements a novel decomposition of the quark species into up- and down-type quark distributions, which is the key to enable a determination of flavor separated parton distributions from a single experiment. The fit is performed on the inclusive unpolarized neutral and charged current cross-section measurements by the H1 collaboration at HERA. The discussion of uncertainties of parton distribution functions is based upon but extends the QCD analysis published together with the H1 data.

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