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Nuclear Theory·nucl-th

Friday·April 29, 2022

4 papers—1 primary·3 cross-listed

All4Primary1Cross-lists3
  1. 01

    [Submitted on 28 Apr 2022]

    Theoretical analysis of the extraction of neutron skin thickness from coherent {\pi}0 photoproduction off nuclei

    F. Colomer🇧🇪 · P. Capel🇧🇪 · M. Ferretti🇩🇪 · J. Piekarewicz🇺🇸 · C. Sfienti🇩🇪 · M. Thiel🇩🇪 · V. Tsaran🇩🇪 · M. Vanderhaeghen🇩🇪

    Background: Coherent {\pi}0 photoproduction on heavy nuclei has been suggested as a reliable tool to infer neutron skin thicknesses. To this aim, various experiments have been performed, especially on 208Pb. Purpose: We analyze the sensitivity of that reaction process to the nucleonic density, and especially to the neutron skin thickness, for 12C, 40Ca and 208Pb, for which reliable data exist, and on 116,124Sn, for which measurements have been performed in Mainz. We study also the role played by the {\pi}0-nucleus final-state interaction. Method: A model of the reaction is developed at the impulse approximation considering either plane waves or distorted waves to describe the {\pi}0-nucleus scattering in the outgoing channel. Results: Our calculations are in good agreement with existing data, especially for 208Pb. The sensitivity of the theoretical cross sections to the choice of the nucleonic density is small, and below the experimental resolution. Conclusions: Coherent {\pi}0 photoproduction is mostly an isoscalar observable that bares no practical sensitivity to the neutron skin thickness. To infer that structure observable it should be coupled to other reaction measurements, such as electron scattering, or by comparing experiments performed on isotopes of the same chemical element.

    Comments:
    Accepted for publication in Phys. Rev. C. One new Ref.[21]
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2204.13395 [pdf]
    PRC(2022)·11 citations
  2. 02

    [Submitted on 27 Apr 2022] (cross-list from hep-ph)

    Compatibility of Neutrino DIS Data and Its Impact on Nuclear Parton Distribution Functions

    K.F.Muzakka🇩🇪 · P.Duwentäster🇩🇪 · T.J.Hobbs🇺🇸 · T.Ježo🇩🇪 · M.Klasen🇩🇪 · K.Kovařík🇩🇪 · A.Kusina🇵🇱 · J.G.Morfín🇺🇸 · F.I.Olness🇺🇸 · R.Ruiz🇵🇱 · I.Schienbein🇫🇷 · J.Y.Yu🇺🇸

    In global analyses of nuclear parton distribution functions (nPDFs), neutrino deep-inelastic scattering (DIS) data have been argued to exhibit tensions with the data from charged-lepton DIS. Using the nCTEQ framework, we investigate these possible tensions both internally and with the data sets used in our recent nPDF analysis nCTEQ15WZSIH. We take into account nuclear effects in the calculation of the deuteron structure function using the CJ15 analysis. The resulting nPDF fit, nCTEQ15WZSIHdeut, serves as the basis for our comparison with inclusive neutrino DIS and charm dimuon production data. Using hypothesis testing, we confirm evidence of tensions with these data and study the impact of the proton PDF baseline as well as the treatment of data correlation and normalization uncertainties. We identify the experimental data and kinematic regions that generate the tensions and present several possible approaches how a consistent global analysis with neutrino data can be performed. We show that the tension can be relieved using a kinematic cut at low () and also investigate a possibility of managing the tensions by using uncorrelated systematic errors. Finally, we present a different approach identifying a subset of neutrino data which leads to a consistent global analysis without any additional cuts. Understanding these tensions between the neutrino and charged-lepton DIS data is important not only for a better flavor separation in global analyses of nuclear and proton PDFs, but also for neutrino physics and for searches for physics beyond the Standard Model.

    Comments:
    33 pages, 25 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    2204.13157 [pdf]
    PRD(2022)·41 citations
  3. 03

    [Submitted on 28 Apr 2022] (cross-list from physics.comp-ph)

    Mathematical formulae for neutron self-shielding properties of media in an isotropic neutron field

    Ateia W. Mahmoud🇪🇬 · Elsayed K. Elmaghraby🇪🇬 · E. Salama🇪🇬 · A. Elghazaly🇪🇬 · S. A. El-fiki🇪🇬

    The complexity of the neutron transport phenomenon throws its shadows on every physical system wherever neutron is produced or used. In the current study, an ab initio derivation of the neutron self-shielding factor to solve the problem of the decrease of the neutron flux as it penetrates into a material placed in an isotropic neutron field. We have employed the theory of steady-state neutron transport, starting from Stuart's formula. Simple formulae were derived based on the integral cross-section parameters that could be adopted by the user according to various variables, such as the neutron flux distribution and geometry of the simulation at hand. The concluded formulae of the self-shielding factors comprise an inverted sigmoid function normalized with a weight representing the ratio between the macroscopic total and scattering cross-sections of the medium. The general convex volume geometries are reduced to a set of chord lengths, while the neutron interactions probabilities within the volume are parameterized to the epithermal and thermal neutron energies. The arguments of the inverted-sigmoid function were derived from a simplified version of neutron transport formulation. Accordingly, the obtained general formulae were successful in giving the values of the experimental neutron self-shielding factor for different elements and different geometries.

    Comments:
    14 pages, 5 figures, 1 graphical abstract, 73 references, and 2 tables, include improvement of illustration and story-telling writing style
    Subjects:
    Computational Physics (physics.comp-ph); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2204.13239 [pdf]
    Phys.Scripta(2024)·1 citation
  4. 04

    [Submitted on 28 Apr 2022] (cross-list from hep-ph)

    First concurrent extraction of the leading-order scalar and spin proton polarizabilities

    E. Mornacchi (1)🇩🇪 · S. Rodini (2)🇩🇪 · B. Pasquini (3 and 4)🇮🇹 · P. Pedroni (4) ((1) Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, Mainz, Germany, (2) Institut für Theoretische Physik, Universität Regensburg, Regensburg, Germany, (3) Dipartimento di Fisica, Università degli Studi di Pavia, Pavia, Italy, (4) INFN Sezione di Pavia, Pavia, Italy)🇮🇹

    We performed the first simultaneous extraction of the six leading-order proton polarizabilities. We reached this milestone thanks to both new high-quality experimental data and an innovative bootstrap-base fitting method. These new results provide a self-consistent and fundamental benchmark for all future theoretical and experimental polarizability estimates.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2204.13491 [pdf]
    PRL(2022)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE