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Nuclear Theory·nucl-th

Friday·November 10, 2017

10 papers—6 primary·4 cross-listed

All10Primary6Cross-lists4
  1. 07

    [Submitted on 8 Nov 2017] (cross-list from hep-ph)

    Probing the time structure of the quark-gluon plasma with top quarks

    Liliana Apolinário🇵🇹 · José Guilherme Milhano🇵🇹 · Gavin P. Salam🇨🇭 · Carlos A. Salgado🇪🇸

    The tiny droplets of Quark Gluon Plasma (QGP) created in high-energy nuclear collisions experience fast expansion and cooling with a lifetime of a few . Despite the information provided by probes such as jet quenching and quarkonium suppression, and the excellent description by hydrodynamical models, direct access to the time evolution of the system remains elusive. We point out that the study of hadronically-decaying bosons, notably in events with a top-antitop quark pair, can provide key novel insight, into the time structure of the QGP. This is because of a unique feature, namely a time delay between the moment of the collision and that when the -boson decay products start interacting with the medium. Furthermore, the length of the time delay can be constrained by selecting specific reconstructed top-quark momenta.

    Comments:
    v1: 5 pages and 5 figures, plus supplemental material. v2: Typos corrected, one reference added. v3: includes additional clarifications; version to be published in Phys.Rev.Lett
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1711.03105 [pdf]
    PRL(2018)·90 citations
  2. 08

    [Submitted on 9 Nov 2017] (cross-list from hep-lat)

    More on heavy tetraquarks in lattice QCD at almost physical pion mass

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

    We report on our progress in studying exotic, heavy tetraquark states, . Using publicly available dynamical Wilson-Clover gauge configurations, generated by the PACS-CS collaboration, with pion masses 164, 299 and 415 MeV, we extend our previous analysis to heavy quark components containing heavier than physical bottom quarks or , charm and bottom quarks and also only charm quarks . Throughout we employ NRQCD and relativistic heavy quarks for the heavier than bottom, bottom and charm quarks. Using our previously established diquark-antidiquark and meson-meson operator basis we comment in particular on the dependence of the binding energy on the mass of the heavy quark component , with heavy quarks ranging from . In the heavy flavor non-degenerate case, , and especially for the tetraquark channel , we extend our work to utilize a GEVP to study the ground and threshold states thereby enabling a clear identification of possible binding. Finally, we present initial work on the system where a much larger operator basis is available in comparison to flavor combinations with NRQCD quarks.

    Comments:
    8 pages, 5 figures, proceedings contribution to "Lattice 2017. 35th International Symposium on Lattice Field Theory", 18th-24th June 2017, Granada, Spain
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1711.03380 [pdf]
    EPJ Web Conf.(2018)·10 citations
  3. 09

    [Submitted on 9 Nov 2017] (cross-list from nucl-ex)

    Formation of pairs in nuclear captures of K mesons

    Raffaele Del Grande🇮🇹 · Kristian Piscicchia🇮🇹 · Slawomir Wycech🇮🇹

    The capture of K mesons on nucleons bound in nuclei offer a chance to study the pairs below the kinematic threshold of the N systems. Various hyperon-pion charged combination are presently under investigation by AMADEUS. These data allow to test both isospin 0 and 1 amplitudes giving the possibility to detect the structure of resonant (1405) state. Contrasted against similar electro-production data, it is possible to detect changes of (1405) in nuclear media. Expected spectra and their uncertainties are calculated.

    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1711.03427 [pdf]
    Acta Phys.Polon.B(2017)·15 citations
  4. 10

    [Submitted on 9 Nov 2017] (cross-list from hep-ph)

    Nonequilibrium quark production in the expanding QCD plasma

    Naoto Tanji🇮🇹 · Juergen Berges🇩🇪

    We perform real-time lattice simulations of nonequilibrium quark production in the longitudinally expanding QCD plasma. Starting from a highly occupied gluonic state with vacuum quark sector, we extract the time evolution of quark and gluon number densities per unit transverse area and rapidity. The total quark number shows after an initial rapid increase an almost linear growth with time. Remarkably, this growth rate appears to be consistent with a simple kinetic theory estimate involving only two-to-two scattering processes in small-angle approximation. This extends previous findings about the role of two-to-two scatterings for purely gluonic dynamics in accordance with the early stages of the bottom-up thermalization scenario.

    Comments:
    33 pages, 23 figures, published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1711.03445 [pdf]
    PRD(2018)·24 citations

Affiliations

first authorsco-authorsvia INSPIRE