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Nuclear Theory·nucl-th

Monday·March 27, 2017

5 papers—3 primary·2 cross-listed

All5Primary3Cross-lists2
  1. 01

    [Submitted on 23 Mar 2017]

    Generalized Nambu-Goldstone pion in dense matter: a schematic NJL model

    Yifan Song🇺🇸 · Gordon Baym🇺🇸

    Chiral symmetry is always broken in cold, dense matter, by chiral condensation at low densities and by diquark condensation at high density. We construct here, within a schematic Nambu-Jona-Lasinio (NJL) model, the corresponding generalized Nambu-Goldstone pion, . As we show, the mode naturally emerges as a linear combination of the vacuum pion and the diquark condensate pion , with the quark field, and continuously evolves with increasing density from being -like in the vacuum to -like in the high density diquark pairing phase. We calculate the density-dependent mass, decay constant, and coupling to quarks of the , and derive a generalized Gell-Mann--Oakes--Renner (GMOR) relation in the presence of a finite bare quark mass . We briefly discuss the implications of the results to possible Bose condensation of in more realistic models.

    Comments:
    15 pages, 7 figures, 1 table
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1703.08236 [pdf]
    PRC(2017)·6 citations
  2. 02

    [Submitted on 24 Mar 2017]

    Linking structure and dynamics in reactions with Borromean nuclei: the LiLi case

    M. Gómez-Ramos · J. Casal · A.M. Moro

    One-neutron removal reactions induced by two-neutron Borromean nuclei are studied within a Transfer-to-the-Continuum (TC) reaction framework, which incorporates the three-body character of the incident nucleus. The relative energy distribution of the residual unbound two-body subsystem, which is assumed to retain information on the structure of the original three-body projectile, is computed by evaluating the transition amplitude for different neutron-core final states in the continuum. These transition amplitudes depend on the overlaps between the original three-body ground-state wave function and the two-body continuum states populated in the reaction, thus ensuring a consistent description of the incident and final nuclei. By comparing different Li three-body models, it is found that the LiLi relative energy spectrum is very sensitive to the position of the and states in Li and to the partial wave content of these configurations within the Li ground-state wave function. The possible presence of a low-lying resonance is discussed. The coupling of the single particle configurations with the non-zero spin of the Li core, which produces a spin-spin splitting of the states, is also studied. Among the considered models, the best agreement with the available data is obtained with a Li model that incorporates the actual spin of the core and contains 31\% of -wave content in the -Li subsystem, in accord with our previous findings for the Li(p,d)Li transfer reaction, and a near-threshold virtual state.

    Comments:
    7 pages, 4 figures, submitted to PLB
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1703.08320 [pdf]
    PLB(2017)·22 citations
  3. 03

    [Submitted on 24 Mar 2017]

    Microscopic studies on nuclear spin-isospin properties---a personal perspective on covariant density functional theory

    Haozhao Liang🇯🇵

    Spin and isospin are essential degrees of freedom in nuclear systems, and the relevant studies on their properties play important roles not only in nuclear physics but also in nuclear astrophysics, particle physics, and so on. In this presentation for the IUPAP Young Scientist Prize 2016, I would like to introduce the microscopic studies on nuclear spin-isospin properties in the framework of covariant density functional theory (DFT), by taking a few works that I have been joining in as examples. It is seen that the covariant scheme plays an important role in describing the spin properties in a consistent way, such as the spin-orbit splitting, the pseudospin symmetry, etc. Meanwhile, the Fock terms play important roles in describing the isospin properties fully self-consistently, such as the Gamow-Teller and spin-dipole resonances, the isospin-symmetry-breaking corrections to nuclear superallowed transitions, etc. To connect the covariant DFT to more fundamental theories, an \textit{ab initio} relativistic Brueckner-Hartree-Fock theory for finite nuclei is introduced, and a personal perspective for the coming decade is also illustrated.

    Comments:
    8 pages, 4 figures, proceedings of INPC2016 (presentation for IUPAP Young Scientist Prize 2016)
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1703.08347 [pdf]
    PoS(2017)·0 citations
  4. 04

    [Submitted on 23 Mar 2017] (cross-list from hep-lat)

    Off-forward gluonic structure of vector mesons

    W. Detmold🇺🇸 · D. Pefkou🇺🇸 · P. E. Shanahan🇺🇸

    The spin-independent and transversity generalised form factors (GFFs) of the meson are studied using lattice QCD calculations with light quark masses corresponding to a pion mass MeV. One transversity and three spin-independent GFFs related to the lowest moments of leading-twist spin-independent and transversity gluon distributions are obtained at six non-zero values of the momentum transfer up to 1.2 GeV. These quantities are compared with the analogous spin-independent quark GFFs and the electromagnetic form factors determined on the same lattice ensemble. The results show quantitative distinction between the spatial distribution of transversely polarised gluons, unpolarised gluons, and quarks, and point the way towards further investigations of the gluon structure of nucleons and nuclei.

    Comments:
    Corrections to Eqs. (7), (8) and the unnumbered equation in Appendix B
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1703.08220 [pdf]
    PRD(2017)·17 citations
  5. 05

    [Submitted on 24 Mar 2017] (cross-list from hep-ph)

    Quark transverse spin-orbit correlations

    Amit Bhoonah (ETH Zürich)🇨🇭 · Cédric Lorcé (Ecole polytechnique, CPHT)🇫🇷

    We extend the study of quark spin-orbit correlations in the nucleon to the case of transverse polarization. At the leading-twist level, this completes the spin structure of the quark kinetic energy-momentum tensor. In particular, we revisit the transversity decomposition of angular momentum proposed a decade ago by Burkardt and introduce a new transverse correlation, namely between quark transversity and orbital angular momentum. We also provide for the first time the Wandzura-Wilczek expression for the second Mellin moment of twist-3 transversity generalized parton distributions, along with a new sum rule. Based on lattice calculation results, we conclude that the quark transverse spin-orbit correlation is negative for both up and down flavors, just like in the longitudinal case.

    Comments:
    7 pages, 1 table
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1703.08322 [pdf]
    PLB(2017)·22 citations

Affiliations

first authorsco-authorsvia INSPIRE