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Nuclear Theory·nucl-th

Friday·December 30, 2016

14 papers—10 primary·4 cross-listed

All14Primary10Cross-lists4
  1. 11

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

    Generalized polarizabilities of the nucleon in baryon chiral perturbation theory

    Vadim Lensky🇩🇪 · Vladimir Pascalutsa🇩🇪 · Marc Vanderhaeghen🇩🇪

    The nucleon generalized polarizabilities (GPs), probed in virtual Compton scattering (VCS), describe the spatial distribution of the polarization density in a nucleon. They are accessed experimentally via the process of electron-proton bremsstrahlung () at electron-beam facilities, such as MIT-Bates, CEBAF (Jefferson Lab), and MAMI (Mainz). We present the calculation of the nucleon GPs and VCS observables at next-to-leading order in baryon chiral perturbation theory (BPT), and confront the results with the empirical information. At this order our results are predictions, in the sense that all the parameters are well-known from elsewhere. Within the relatively large uncertainties of our calculation we find good agreement with the experimental observations of VCS and the empirical extractions of the GPs. We find large discrepancies with previous chiral calculations---all done in heavy-baryon PT (HBPT)---and discuss the differences between BPT and HBPT responsible for these discrepancies.

    Comments:
    25 pages, 11 figures, ReVTeX4, references updated, typos corrected, supplementary material (a Mathematica notebook) added, matches the published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1612.08626 [pdf]
    EPJC(2017)·23 citations
  2. 12

    [Submitted on 20 Dec 2016] (cross-list from cond-mat.mtrl-sci)

    Fitting of structural parameters to small angle neutron scattering data for nickel-chromium-aluminum alloy in frames of quantum mechanics and classic models of polydispersed spheres

    S.I.Potashev · V.P.Zavarzina · A.A.Afonin · R.A.Sadykov (Institute for Nuclear Researches of Russian Academy of Sciences)

    Modified Yukawa's potential is used to fit model parameters of nucleus to the small angle thermal neutron scattering data on the nickel-chromium-aluminum alloy at the transferred momentum and effective nucleus radius production satisfied by condition . Analytical polydisperse sphere model is used to calculate a neutron scattering intensity and to determine most probable macroscopic sphere radius at . Combination of gauss, Relay and Schulze-Zimm distributions can be used to fit model parameters to experimental data. Fast algorithm and program of fitting to data is proposed.

    Comments:
    10 pages, 5 figures, 1 table
    Subjects:
    cond-mat.mtrl-sci (cond-mat.mtrl-sci); Nuclear Theory (nucl-th)
    arXiv:
    1612.09115 [pdf]
    0 citations
  3. 13

    [Submitted on 29 Dec 2016] (cross-list from hep-ph)

    Ab initio nuclear response functions for dark matter searches

    Daniel Gazda🇸🇪 · Riccardo Catena🇸🇪 · Christian Forssén🇸🇪

    We study the process of dark matter particles scattering off He with nuclear wave functions computed using an ab initio many-body framework. We employ realistic nuclear interactions from chiral effective field theory at next-to-next-to-leading order (NNLO) and develop an ab initio scheme to compute a general set of different nuclear response functions. In particular, we then perform an accompanying uncertainty quantification on these quantities and study error propagation to physical observables. We find a rich structure of allowed nuclear responses with significant uncertainties for certain spin-dependent interactions. The approach and results that are presented in this Paper establish a new framework for nuclear structure calculations and uncertainty quantification in the context of direct and (certain) indirect searches for dark matter.

    Comments:
    version accepted for publication in Phys. Rev. D; figures revised (incl. corrected labels); discussion of results extended
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Nuclear Theory (nucl-th)
    arXiv:
    1612.09165 [pdf]
    PRD(2017)·51 citations
  4. 14

    [Submitted on 29 Dec 2016] (cross-list from hep-ph)

    Excited Scalar and Pseudoscalar Mesons in the Extended Linear Sigma Model

    Denis Parganlija🇦🇹 · Francesco Giacosa🇩🇪

    We present an in-depth study of masses and decays of excited scalar and pseudoscalar states in the Extended Linear Sigma Model (eLSM). The model also contains ground-state scalar, pseudoscalar, vector and axial-vector mesons. The main objective is to study the consequences of the hypothesis that the resonance, observed a decade ago by the BES Collaboration and recently by LHCb, represents an excited scalar quarkonium. In addition we also analyse the possibility that the new resonance, observed recently by BABAR, may also be an excited scalar state. Both hypotheses receive justification in our approach although there appears to be some tension between the simultaneous interpretation of / and pseudoscalar mesons , , and as excited states.

    Comments:
    28 pages, 6 tables, 1 figure. v2 (published version) contains further clarification of the model and results; typos have been corrected and references added
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1612.09218 [pdf]
    EPJC(2017)·39 citations

Affiliations

first authorsco-authorsvia INSPIRE