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Nuclear Theory·nucl-th

Friday·January 29, 2016

10 papers—5 primary·5 cross-listed

All10Primary5Cross-lists5
  1. 06

    [Submitted on 14 Jan 2016] (cross-list from cond-mat.str-el)

    Sum-rules and Goldstone modes from extended RPA theories in Fermi systems with spontaneously broken symmetries

    D.S. Delion🇷🇴 · P. Schuck🇫🇷 · M. Tohyama🇯🇵

    The Self-Consistent RPA (SCRPA) approach is elaborated for cases with a continuously broken symmetry, this being the main focus of the present article. Correlations beyond standard RPA are summed up correcting for the quasi-boson approximation in standard RPA. Desirable properties of standard RPA such as fullfillment of energy weighted sum rule and appearance of Goldstone (zero) modes are kept. We show theoretically and, for a model case, numerically that, indeed, SCRPA maintains all properties of standard RPA for practically all situations of spontaneously broken symmetries. A simpler approximate form of SCRPA, the so-called renormalised RPA, also has these properties. The SCRPA equations are first outlined as an eigenvalue problem, but it is also shown how an equivalent many body Green's function approach can be formulated.

    Comments:
    13 pages, 8 figures
    Subjects:
    Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
    arXiv:
    1601.03495 [pdf]
    Eur.Phys.J.B(2016)·5 citations
  2. 07

    [Submitted on 27 Jan 2016] (cross-list from hep-ph)

    Atomic ionization by sterile-to-active neutrino conversion and constraints on dark matter sterile neutrinos with germanium detectors

    Jiunn-Wei Chen🇺🇸 · Hsin-Chang Chi🇹🇼 · Shin-Ted Lin🇨🇳 · C.-P. Liu🇹🇼 · Lakhwinder Singh🇮🇳 · Henry T. Wong🇹🇼 · Chih-Liang Wu🇹🇼 · Chih-Pan Wu🇹🇼

    The transition magnetic moment of a sterile-to-active neutrino conversion gives rise to not only radiative decay of a sterile neutrino, but also its non-standard interaction (NSI) with matter. For sterile neutrinos of keV-mass as dark matter candidates, their decay signals are actively searched for in cosmic X-ray spectra. In this work, we consider the NSI that leads to atomic ionization, which can be detected by direct dark matter experiments. It is found that this inelastic scattering process for a nonrelativistic sterile neutrino has a pronounced enhancement in the differential cross section at energy transfer about half of its mass, manifesting experimentally as peaks in the measurable energy spectra. The enhancement effects gradually smear out as the sterile neutrino becomes relativistic. Using data taken with germanium detectors that have fine energy resolution in keV and sub-keV regimes, constraints on sterile neutrino mass and its transition magnetic moment are derived and compared with those from astrophysical observations.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1601.07257 [pdf]
    PRD(2016)·15 citations
  3. 08

    [Submitted on 28 Jan 2016] (cross-list from hep-ph)

    Probing the transversity spin structure of a nucleon in neutrino-production of a charmed meson

    B. Pire🇫🇷 · L. Szymanowski🇵🇱 · J. Wagner🇵🇱

    Including O(m_c) terms in the coefficient functions and/or O(m_D) twist 3 contributions in the heavy meson distribution amplitudes leads to a non-zero transverse amplitude for exclusive neutrino production of a D pseudoscalar charmed meson on an unpolarized target. We work in the framework of the collinear QCD approach where chiral-odd transversity generalized parton distributions (GPDs) factorize from perturbatively calculable coefficient functions.

    Comments:
    6 pages, 2 figures, 6th international conference on Physics Opportunities at an Electron-Ion Collider, POETIC-6, September 7-11 2015, Ecole polytechnique, Palaiseau, France; v2 : eq.10 and Fig. 2 corrected
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1601.07666 [pdf]
    EPJ Web Conf.(2016)·8 citations
  4. 09

    [Submitted on 28 Jan 2016] (cross-list from hep-ph)

    Examination of directed flow as a signature of the softest point of the equation of state in QCD matter

    Yasushi Nara🇯🇵 · Harri Niemi🇩🇪 · Akira Ohnishi🇯🇵 · Horst Stoecker🇩🇪

    We analyze the directed flow of protons and pions in high-energy heavy-ion collisions in the incident energy range from to 27 GeV within a microscopic transport model. Standard hadronic transport approaches do not describe the collapse of directed flow below GeV. By contrast, a model which simulates effects of a softening of the equation of state, well describes the behavior of directed flow data recently obtained by the STAR Collaboration~\cite{STARv1}. We give a detailed analysis of how directed flow is generated. Particularly, we found that softening of effective equation of state at the overlapping region of two nuclei, i.e. the reaction stages where the system reaches high baryon density state, is needed to explain the observed collapse of proton directed flow within a hadronic transport approach.

    Comments:
    11 pages, 12 figures. Typos fixed, version accepted in PRC
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1601.07692 [pdf]
    PRC(2016)·96 citations
  5. 10

    [Submitted on 28 Jan 2016] (cross-list from hep-ph)

    Iterative Monte Carlo analysis of spin-dependent parton distributions

    Nobuo Sato🇺🇸 · W. Melnitchouk🇺🇸 · S. E. Kuhn🇺🇸 · J. J. Ethier🇺🇸 · A. Accardi🇺🇸

    We present a comprehensive new global QCD analysis of polarized inclusive deep-inelastic scattering, including the latest high-precision data on longitudinal and transverse polarization asymmetries from Jefferson Lab and elsewhere. The analysis is performed using a new iterative Monte Carlo fitting technique which generates stable fits to polarized parton distribution functions (PDFs) with statistically rigorous uncertainties. Inclusion of the Jefferson Lab data leads to a reduction in the PDF errors for the valence and sea quarks, as well as in the gluon polarization uncertainty at . The study also provides the first determination of the flavor-separated twist-3 PDFs and the moment of the nucleon within a global PDF analysis.

    Comments:
    54 pages, 18 figures, 6 tables; to appear in Phys. Rev. D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1601.07782 [pdf]
    PRD(2016)·191 citations

Affiliations

first authorsco-authorsvia INSPIRE