PaperPanorama
FAQ

Nuclear Theory·nucl-th

Thursday·March 8, 2018

5 papers—3 primary·2 cross-listed

All5Primary3Cross-lists2
  1. 04

    [Submitted on 7 Mar 2018] (cross-list from hep-lat)

    Reconstruction of light-cone parton distribution functions from lattice QCD simulations at the physical point

    Constantia Alexandrou🇨🇾 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Karl Jansen🇩🇪 · Aurora Scapellato🇨🇾 · Fernanda Steffens🇩🇪

    We present the unpolarized and helicity parton distribution functions calculated within lattice QCD simulations using physical values of the light quark mass. Non-perturbative renormalization is employed and the lattice data are converted to the MSbar-scheme at a scale of 2 GeV. A matching process is applied together with target mass corrections leading to the reconstruction of light-cone parton distribution functions. For both cases we find a similar behavior between the lattice and phenomenological data, and for the polarized PDF a nice overlap for a range of Bjorken-x values. This presents a major success for the emerging field of direct calculations of quark distributions using lattice QCD.

    Comments:
    6 pages, 6 figures, 1 table
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1803.02685 [pdf]
    PRL(2018)·204 citations
  2. 05

    [Submitted on 7 Mar 2018] (cross-list from hep-ph)

    Mapping the sensitivity of hadronic experiments to nucleon structure

    Bo-Ting Wang🇺🇸 · T. J. Hobbs🇺🇸 · Sean Doyle🇺🇸 · Jun Gao🇨🇳 · Tie-Jiun Hou🇨🇳 · Pavel M. Nadolsky🇺🇸 · Fredrick I. Olness🇺🇸

    Determinations of the proton's collinear parton distribution functions (PDFs) are emerging with growing precision due to increased experimental activity at facilities like the Large Hadron Collider. While this copious information is valuable, the speed at which it is released makes it difficult to quickly assess its impact on the PDFs, short of performing computationally expensive global fits. As an alternative, we explore new methods for quantifying the potential impact of experimental data on the extraction of proton PDFs. Our approach relies crucially on the Hessian correlation between theory-data residuals and the PDFs themselves, as well as on a newly defined quantity --- the sensitivity --- which represents an extension of the correlation and reflects both PDF-driven and experimental uncertainties. This approach is realized in a new, publicly available analysis package PDFSense, which operates with these statistical measures to identify particularly sensitive experiments, weigh their relative or potential impact on PDFs, and visualize their detailed distributions in a space of the parton momentum fraction and factorization scale . This tool offers a new means of understanding the influence of individual measurements in existing fits, as well as a predictive device for directing future fits toward the highest impact data and assumptions. Along the way, many new physics insights can be gained or reinforced. As one of many examples, PDFSense is employed to rank the projected impact of new LHC measurements in jet, vector boson, and production and leads us to the conclusion that inclusive jet production at the LHC has a potential for playing an indispensable role in future PDF fits. These conclusions are independently verified by preliminarily fitting this experimental information and investigating the constraints they supply using the Lagrange multiplier technique.

    Comments:
    43 pages, 10 figures, 17 tables --- published in Phys. Rev. D and validated against Lagrange Multiplier scans in Sect.IV.D. Minor clarification added to Table XIV of the Supplemental Material
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1803.02777 [pdf]
    PRD(2018)·47 citations

Affiliations

first authorsco-authorsvia INSPIRE