A new generation of parton distribution functions with increased precision and quantitative estimates of uncertainties is presented. This work signiflcantly extends previous CTEQ and other global analyses on two fronts: (i) a full treatment of available experimental correlated systematic errorsforbothnewandolddata sets; (ii) asystematic and pragmatic treatment of uncertainties of the parton distributions and their physical predictions, using a recently developed eigenvector-basis approach to the hessian method. The new gluon distribution is considerably harder than that of previous standard flts. A numberofphysicsissues,particularlyrelatingtothebehaviorofthegluondistribution,are addressedinmorequantitativetermsthanbefore. Extensiveresultsontheuncertaintiesof parton distributions at various scales, and on parton luminosity functions at the Tevatron RunII and the LHC, are presented. The latter provide the means to quickly estimate the uncertainties of a wide range of physical processes at these high-energy hadron colliders, basedoncurrentknowledgeofthepartondistributions. Inparticular, theuncertaintieson the production cross sections of the W, Z at the Tevatron and the LHC are estimated to be§4% and§5%, respectively, and that of a light Higgs at the LHC to be§5%.

/pdf/new-generation-of-parton-distributions-with-uncertainties-4f8pm2a8i5.pdf

New generation of parton distributions with uncertainties from global QCD analysis

We present updated leading-order, next-to-leading order and next-to-next-to-leading order parton distribution functions (“MSTW 2008”) determined from global analysis of hard-scattering data within the standard framework of leading-twist fixed-order collinear factorisation in the $\overline{\mathrm{MS}}$
 
scheme. These parton distributions supersede the previously available “MRST” sets and should be used for the first LHC data taking and for the associated theoretical calculations. New data sets fitted include CCFR/NuTeV dimuon cross sections, which constrain the strange-quark and -antiquark distributions, and Tevatron Run II data on inclusive jet production, the lepton charge asymmetry from W decays and the Z rapidity distribution. Uncertainties are propagated from the experimental errors on the fitted data points using a new dynamic procedure for each eigenvector of the covariance matrix. We discuss the major changes compared to previous MRST fits, briefly compare to parton distributions obtained by other fitting groups, and give predictions for the W and Z total cross sections at the Tevatron and LHC.

/pdf/parton-distributions-for-the-lhc-4lvvi85r8i.pdf

Parton distributions for the LHC

We present NNPDF3.0, the first set of parton distribution functions (PDFs) determined with a methodology validated by a closure test. NNPDF3.0 uses a global dataset including HERA-II deep-inelastic inclusive cross-sections, the combined HERA charm data, jet production from ATLAS and CMS, vector boson rapidity and transverse momentum distributions from ATLAS, CMS and LHCb, W+c data from CMS and top quark pair production total cross sections from ATLAS and CMS. Results are based on LO, NLO and NNLO QCD theory and also include electroweak corrections. To validate our methodology, we show that PDFs determined from pseudo-data generated from a known underlying law correctly reproduce the statistical distributions expected on the basis of the assumed experimental uncertainties. This closure test ensures that our methodological uncertainties are negligible in comparison to the generic theoretical and experimental uncertainties of PDF determination. This enables us to determine with confidence PDFs at different perturbative orders and using a variety of experimental datasets ranging from HERA-only up to a global set including the latest LHC results, all using precisely the same validated methodology. We explore some of the phenomenological implications of our results for the upcoming 13 TeV Run of the LHC, in particular for Higgs production cross-sections.

/pdf/parton-distributions-for-the-lhc-run-ii-3k5n4fqkie.pdf

Parton distributions for the LHC Run II

Parton distributions with LHC data

Parton distribution functions (PDFs) are crucial ingredients for the calculation of the relevant cross sections for various scattering processes at the Large Hadron Collider (LHC). Including data from several previous experiments, the authors find new PDFs, which will be important for the data analysis at the LHC Run-2.

New parton distribution functions from a global analysis of quantum chromodynamics

Measurements of the ratio of Drell-Yan yields from an $800 \mathrm{GeV}/c$ proton beam incident on liquid hydrogen and deuterium targets are reported. Approximately 360 000 Drell-Yan muon pairs remained after all cuts on the data. From these data, the ratio of down antiquark $(\overline{d})$ to up $(\ifmmode \bar{u}\else \={u}\fi{})$ antiquark distributions in the proton sea is determined over a wide range in Bjorken-$x.$ These results confirm previous measurements by E866 and extend them to lower x. From these data, $(\overline{d}\ensuremath{-}\ifmmode \bar{u}\else \={u}\fi{})$ and $\ensuremath{\int}(\overline{d}\ensuremath{-}\ifmmode \bar{u}\else \={u}\fi{})dx$ are evaluated for $0.015lxl0.35.$ These results are compared with parametrizations of various parton distribution functions, models and experimental results from NA51, NMC and HERMES.

Improved measurement of the d̄/ū asymmetry in the nucleon sea

Objective: To analyze the expression of C-X-C chemokine receptor 5 (CXCR5)+CD8+ T cells and plasma C-X-C motif chemokine 13 (CXCL13) in severe aplastic anemia (SAA) patients and their correlations with hematological parameters. Methods: The clinical data of 35 SAA patients in the Hematology Department of Tianjin Medical University General Hospital from January 2018 to September 2021 were retrospectively analyzed. The patients were divided into two groups according to whether they had received the medication: untreated SAA group and recovery SAA group. In untreated group, there were 18 patients who had not received any medication, with 9 males and 9 females, and aged 51 (18-76) years. In recovery SAA group, there were 17 patients who were separated from component blood transfusion after the immunosuppressive treatment with anti-thymocyte globulin (ATG) combined with cyclosporine A (CsA), with 7 males and 10 females, and aged 46 (16-70) years. Meanwhile, 20 healthy controls were also selected, including 8 males and 12 females, and aged 45(15-72) years. Peripheral blood and bone marrow samples were collected from SAA patients, while peripheral blood samples were obtained from healthy controls. Flow cytometry was used to detect the percentage of CXCR5+CD8+ T cells in peripheral blood and bone marrow samples. The concentration of plasma CXCL13 was measured by enzyme-linked immunosorbent assay (ELISA). The correlations between the percentage of CXCR5+CD8+ T cells and the concentration of CXCL13, as well as the correlations between these two parameters and the hematological parameters were analyzed by Spearman correlation analysis. Results: The proportion of CXCR5+CD8+ T cells in the bone marrow of untreated SAA group was (4.9±2.9)%, which was higher than that of recovery SAA group (2.7±1.5)%, with a statistically significant difference (t=2.34, P=0.027). The proportion of CXCR5+CD8+ T cells in peripheral blood of untreated SAA group, recovery SAA group and healthy control group was (8.4±4.2)%, (3.8±2.3)% and (2.6±2.0)% respectively. The proportion of CXCR5+CD8+ T cells in peripheral blood of untreated SAA group was higher than that of recovery SAA group and healthy control group (both P<0.05). The plasma CXCL13 concentration in untreated SAA group was (97.2±46.8) ng/L, which was significantly higher than that in recovery SAA group [(54.9±20.9) ng/L] and healthy control group [(47.6±17.3) ng/L] (both P<0.05). The proportion of CXCR5+CD8+ T cells in peripheral blood of SAA patients was positively correlated with the concentration of plasma CXCL13 (r=0.545, P<0.001). The proportion of peripheral blood CXCR5+CD8+ T cells in SAA patients was negatively correlated with white blood cell count, platelets count, percentage of neutrophils, absolute neutrophils count, percentage of reticulocytes, absolute reticulocytes count, bone marrow myeloid cells, bone marrow erythroid cells and megakaryocytes count (r=-0.556, -0.392, -0.617, -0.615, -0.395, -0.543, -0.432, -0.484 and -0.523, all P<0.05). The proportion of peripheral blood CXCR5+CD8+ T cells was positively correlated with the percentage of peripheral blood lymphocytes and bone marrow lymphoid cells (r=0.593 and 0.556, both P<0.05). Meanwhile, the concentration of plasma CXCL13 in SAA patients was negatively correlated with white blood cell count, absolute neutrophils count, percentage of reticulocytes, absolute reticulocytes count and bone marrow myeloid cells (r=-0.447, -0.446, -0.498, -0.407 and -0.456, all P<0.05), but positively correlated with bone marrow lymphoid cells (r=0.384, P<0.05). Conclusions: The proportion of CXCR5+CD8+ T cells and the concentration of plasma CXCL13 increases in SAA patients. The proportion of CXCR5+CD8+ T cells in peripheral blood is positively correlated with the concentration of CXCL13. Moreover, the proportion of CXCR5+CD8+ T cells and the concentration of CXCL13 are correlated with many hematological parameters, which may play a critical role in the immune pathogenesis of SAA.

[Abnormal expression of CXCR5+CD8+ T cells and CXCL13 in severe aplastic anemia patients and their correlation with hematological parameters].

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Y. C. Wang

Author Tools

Chat about Author

Papers

Improved measurement of the d̄/ū asymmetry in the nucleon sea

[Abnormal expression of CXCR5+CD8+ T cells and CXCL13 in severe aplastic anemia patients and their correlation with hematological parameters].