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Nuclear Theory·nucl-th

Thursday·March 8, 2018

5 papers—3 primary·2 cross-listed

All5Primary3Cross-lists2
  1. 01

    The Deconfinement Phase Transition in Proto-Neutron-Star Matter

    J. Roark🇺🇸 · V. Dexheimer🇺🇸

    In this work, we study in detail the deconfinement phase transition that takes place in hot/dense nuclear matter in the context of neutron stars and proto-neutron stars (in which lepton fraction is fixed). The possibility of different mixtures of phases with different locally and globally conserved quantities is considered in each case. For this purpose, the Chiral Mean Field (CMF) model, an effective relativistic model that includes self-consistent chiral symmetry restoration and deconfinement to quark matter, is employed. Finally, we compare our results with data provided by PQCD for different temperatures and conditions.

    nucl-thastro-ph.HEastro-ph.SRPRC(2018)·48 citations
  2. 02

    Open charm and dileptons from relativistic heavy-ion collisions

    Taesoo Song🇩🇪 · Wolfgang Cassing🇩🇪 · Pierre Moreau🇩🇪 · Elena Bratkovskaya🇩🇪

    Dileptons are considered as one of the cleanest signals of the quark-gluon plasma (QGP), however, the QGP radiation is masked by many 'background' sources from either hadronic decays or semileptonic decays from correlated charm pairs. In this study we investigate the relative contribution of these channels in heavy-ion collisions from 8 GeV to 5 TeV with a focus on the competition between the thermal QGP radiation and the semileptonic decays from correlated meson pairs. As a 'tool' we employ the parton-hadron-string dynamics (PHSD) transport approach to study dilepton spectra in Pb+Pb (Au+Au) collisions in a wide energy range incorporating for the first time a fully microscopic treatment of the charm dynamics and their semileptonic decays. We find that the dileptons from correlated meson decays dominate the 'thermal' radiation from the QGP in central Pb+Pb collisions at the intermediate masses (1.2 GeV 3 GeV) for 40 GeV, while for 8 to 20 GeV the contribution from decays to the intermediate mass dilepton spectra is subleading such that one should observe a rather clear signal from the QGP radiation. We, furthermore, study the -spectra and the of single electrons at different energies as well as the excitation function of the inverse slope of the - spectra for intermediate-mass dileptons from the QGP and from charm decays. We find moderate but characteristic changes in the inverse slope parameter for 20 GeV which can be observed experimentally in high statistics data. Additionally, we provide detailed predictions for dilepton spectra from Pb+Pb collisions at 5.02 TeV.

    nucl-thhep-phPRC(2018)·61 citations
  3. 03

    Neutron star tidal deformabilities constrained by nuclear theory and experiment

    Yeunhwan Lim · Jeremy W. Holt

    We confront observational data from gravitational wave event GW170817 with microscopic modeling of the cold neutron star equation of state. We develop and employ a Bayesian statistical framework that enables us to implement constraints on the equation of state from laboratory measurements of nuclei and state-of-the-art chiral effective field theory methods. The energy density functionals constructed from the posterior probability distributions are then used to compute consistently the neutron star equation of state from the outer crust to the inner core, assuming a composition consisting of protons, neutrons, electrons, and muons. In contrast to previous studies, we find that the 95% credibility range of predicted neutron star tidal deformabilities () for a 1.4 solar-mass neutron star is already consistent with the upper bound deduced from observations of the GW170817 event. However, we find that lower bounds on the neutron star tidal deformability will very strongly constrain microscopic models of the dense matter equation of state. We also demonstrate a strong correlation between the neutron star tidal deformability and the pressure of beta-equilibrated matter at twice saturation density.

    nucl-thastro-ph.HEPRL(2018)·210 citations
  4. 04

    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.

    ↳ hep-lathep-exhep-phnucl-thPRL(2018)·204 citations
  5. 05

    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.

    ↳ hep-phhep-exnucl-thPRD(2018)·47 citations

Affiliations

first authorsco-authorsvia INSPIRE