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Nuclear Theory·nucl-th

Friday·October 26, 2018

7 papers—2 primary·5 cross-listed

All7Primary2Cross-lists5
  1. 03

    [Submitted on 24 Oct 2018] (cross-list from hep-lat)

    Evidence for charm-bottom tetraquarks and the mass dependence of heavy-light tetraquark states from lattice QCD

    Anthony Francis🇨🇭 · Renwick J. Hudspith🇨🇦 · Randy Lewis🇨🇦 · Kim Maltman🇨🇦

    We continue our study of heavy-light four-quark states and find evidence from lattice QCD for the existence of a strong-interaction-stable tetraquark with mass in the range of 15 to 61 MeV below threshold. Since this range includes the electromagnetic decay threshold, current uncertainties do not allow us to determine whether such a state would decay electromagnetically, or only weakly. We also perform a study at fixed pion mass, with NRQCD for the heavy quarks, simulating and tetraquarks with or and variable, unphysical in order to investigate the heavy mass-dependence of such tetraquark states. We find that the dependence of the binding energy follows a phenomenologically-expected form and that, though NRQCD breaks down before is reached, the results at higher clearly identify the channel as the most likely to support a strong-interaction-stable tetraquark state at . This observation serves to motivate the direct simulation. Throughout we use dynamical ensembles with pion masses 415, 299, and 164 MeV reaching down almost to the physical point, a relativistic heavy quark prescription for the charm quark, and NRQCD for the bottom quark(s).

    Comments:
    24 pages, 4 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1810.10550 [pdf]
    PRD(2019)·140 citations
  2. 04

    [Submitted on 24 Oct 2018] (cross-list from hep-ph)

    Prescaling and far-from-equilibrium hydrodynamics in the quark-gluon plasma

    Aleksas Mazeliauskas🇩🇪 · Jürgen Berges🇩🇪

    Prescaling is a far-from-equilibrium phenomenon which describes the rapid establishment of a universal scaling form of distributions much before the universal values of their scaling exponents are realized. We consider the example of the spatio-temporal evolution of the quark-gluon plasma explored in heavy-ion collisions at sufficiently high energies. Solving QCD kinetic theory with elastic and inelastic processes, we demonstrate that the gluon and quark distributions very quickly adapt a self-similar scaling form, which is independent of initial condition details and system parameters. The dynamics in the prescaling regime is then fully encoded in a few time-dependent scaling exponents, whose slow evolution gives rise to far-from-equilibrium hydrodynamic behavior.

    Comments:
    6 pages, 6 figures, v2 rewrote conclusion, other minor changes, published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1810.10554 [pdf]
    PRL(2019)·82 citations
  3. 05

    [Submitted on 24 Oct 2018] (cross-list from nucl-ex)

    Consequences of broken axial symmetry in heavy nuclei -- an overview of the situation in the valley of stability

    Eckart Grosse🇩🇪 · Arnd R. Junghans🇩🇪 · Jonathan N. Wilson🇫🇷

    An overview on the various effects of axial symmetry breaking is presented for medium heavy and heavy nuclei covering the mass number range 70 < A <240. The discussion includes various observations for nuclei: level densities, spectroscopic features as energies and transition rates, ground state masses and finally the splitting of giant dipole resonances. Quadrupole moments and rates can be derived from models of triaxial rigid rotation or cranking for a given triaxiality parameters {\gamma}, but microscopic considerations are needed to predict these for each nucleus investigated. Respective predictions were made by recently made Hartree- Fock-Bogolyubov (HFB) calculations extended to arbitrary triaxiality by a generator coordinate method. In accord to these, various observations as reported in this overview demonstrate the importance of allowing a breaking of axial symmetry for heavy nuclei already in the valley of stability. Considering this breaking as indicated from the HFB approach surprisingly many experimental data are well described globally without the need for local fit parameters. In addition to these comparisons it will be shown that it is advantageous to consider c{\gamma}=cos(3{\gamma}) an indicator of axiality for heavy nuclei independent of their quadrupole moment.

    Comments:
    15 pages, 9 figures, to be published in Physica Scripta in a special focus issue on Nuclear Shapes and Symmetries
    Subjects:
    Nuclear Experiment (nucl-ex); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
    arXiv:
    1810.10564 [pdf]
    Phys.Scripta(2019)·2 citations
  4. 06

    [Submitted on 24 Oct 2018] (cross-list from nucl-ex)

    First Measurement of the Ar Cross Section at Jefferson Lab

    H. Dai🇺🇸 · M. Murphy🇺🇸 · V. Pandey🇺🇸 · D. Abrams🇺🇸 · D. Nguyen🇺🇸 · B. Aljawrneh🇺🇸 · S. Alsalmi🇺🇸 · A. M. Ankowski🇺🇸 · J. Bane🇺🇸 · S. Barcus🇺🇸 · O. Benhar🇮🇹 · V. Bellini🇮🇹 and 46 other authors

    The success of the ambitious programs of both long- and short-baseline neutrino-oscillation experiments employing liquid-argon time-projection chambers will greatly rely on the precision with which the weak response of the argon nucleus can be estimated. In the E12-14-012 experiment at Jefferson Lab Hall A, we have studied the properties of the argon nucleus by scattering a high-quality electron beam off a high-pressure gaseous argon target. Here, we present the measured Ar double differential cross section at incident electron energy ~GeV and scattering angle . The data cover a broad range of energy transfers, where quasielastic scattering and delta production are the dominant reaction mechanisms. The result for argon is compared to our previously reported cross sections for titanium and carbon, obtained in the same kinematical setup.

    Comments:
    6 pages, 4 figures
    Subjects:
    Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1810.10575 [pdf]
    PRC(2019)·49 citations
  5. 07

    [Submitted on 25 Oct 2018] (cross-list from hep-ph)

    Matching the Quasi Meson Distribution Amplitude in RI/MOM scheme

    Yu-Sheng Liu🇨🇳 · Wei Wang🇨🇳 · Ji Xu🇨🇳 · Qi-An Zhang🇨🇳 · Shuai Zhao🇨🇳 · Yong Zhao🇺🇸

    The -dependence of light-cone distribution amplitude (LCDA) can be directly calculated from a quasi distribution amplitude (DA) in lattice QCD within the framework of large-momentum effective theory (LaMET). In this paper, we study the one-loop renormalization of the quasi-DA in the regularization-independent momentum subtraction (RI/MOM) scheme. The renormalization factor for the quasi parton distribution function can be used to renormalize the quasi-DA provided that they are implemented on lattice and in perturbation theory in the same manner. We derive the one-loop matching coefficient that matches quasi-DA in the RI/MOM scheme onto LCDA in the scheme. Our result provides the crucial step to extract the LCDAs from lattice matrix elements of quasi-DAs.

    Comments:
    7 pages, 0 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1810.10879 [pdf]
    PRD(2019)·46 citations

Affiliations

first authorsco-authorsvia INSPIRE