PaperPanorama
FAQ

Nuclear Theory·nucl-th

Wednesday·July 29, 2020

5 papers—1 primary·4 cross-listed

All5Primary1Cross-lists4
  1. 01

    [Submitted on 28 Jul 2020]

    Variational Monte Carlo calculations of nuclei with an artificial neural-network correlator ansatz

    Corey Adams🇺🇸 · Giuseppe Carleo🇺🇸 · Alessandro Lovato🇮🇹 · Noemi Rocco🇺🇸

    The complexity of many-body quantum wave functions is a central aspect of several fields of physics and chemistry where non-perturbative interactions are prominent. Artificial neural networks (ANNs) have proven to be a flexible tool to approximate quantum many-body states in condensed matter and chemistry problems. In this work we introduce a neural-network quantum state ansatz to model the ground-state wave function of light nuclei, and approximately solve the nuclear many-body Schrödinger equation. Using efficient stochastic sampling and optimization schemes, our approach extends pioneering applications of ANNs in the field, which present exponentially-scaling algorithmic complexity. We compute the binding energies and point-nucleon densities of nuclei as emerging from a leading-order pionless effective field theory Hamiltonian. We successfully benchmark the ANN wave function against more conventional parametrizations based on two- and three-body Jastrow functions, and virtually-exact Green's function Monte Carlo results.

    Comments:
    4 pages, 2 figures
    Subjects:
    Nuclear Theory (nucl-th); cond-mat.dis-nn (cond-mat.dis-nn); Quantum Physics (quant-ph)
    arXiv:
    2007.14282 [pdf]
    PRL(2021)·111 citations
  2. 02

    [Submitted on 27 Jul 2020] (cross-list from hep-ph)

    Discovering partonic rescattering in light nucleus collisions

    Alexander Huss🇨🇭 · Aleksi Kurkela🇨🇭 · Aleksas Mazeliauskas🇨🇭 · Risto Paatelainen🇨🇭 · Wilke van der Schee🇨🇭 · Urs Achim Wiedemann🇨🇭

    We demonstrate that oxygen-oxygen (OO) collisions at the LHC provide unprecedented sensitivity to parton energy loss in a system whose size is comparable to those created in very peripheral heavy-ion collisions. With leading and next-to-leading order calculations of nuclear modification factors, we show that the baseline in the absence of partonic rescattering is known with up to 2% theoretical accuracy in inclusive OO collisions. Surprisingly, a -boson normalized nuclear modification factor does not lead to higher theoretical accuracy within current uncertainties of nuclear parton distribution functions. We study a broad range of parton energy loss models and we find that the expected signal of partonic rescattering can be disentangled from the baseline by measuring charged hadron spectra in the range

    Comments:
    8 pages, 7 figures, see the companion paper "Predicting parton energy loss in small collision systems"; v2: added NLO hadron baseline calculations, small changes, published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2007.13754 [pdf]
    PRL(2021)·73 citations
  3. 03

    [Submitted on 27 Jul 2020] (cross-list from hep-ph)

    Predicting parton energy loss in small collision systems

    Alexander Huss🇨🇭 · Aleksi Kurkela🇨🇭 · Aleksas Mazeliauskas🇨🇭 · Risto Paatelainen🇨🇭 · Wilke van der Schee🇨🇭 · Urs Achim Wiedemann🇨🇭

    Medium induced parton energy loss is not conclusively established neither in very peripheral heavy-ion collisions nor in proton-ion collisions. However, the standard interpretation of azimuthal momentum anisotropies in theses systems implies some partonic rescattering. The upcoming light-ion runs at the LHC provide a unique opportunity to search for parton energy loss in different systems of similar size. Here, we make predictions for the expected parton energy loss signal in the charged hadron spectra in a system size scan at LHC. We test a large set of model assumptions against the transverse momentum and centrality dependence of the charged hadron nuclear modification factor in lead-lead and xenon-xenon collisions at the LHC. We then attempt to make a model agnostic prediction for the charged hadron nuclear modification factor in oxygen-oxygen collisions.

    Comments:
    19 pages, 14 figures, companion paper of "Discovering partonic rescattering in light nucleus collisions"; v2: small corrections and updates, published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2007.13758 [pdf]
    PRC(2021)·84 citations
  4. 04

    [Submitted on 27 Jul 2020] (cross-list from hep-lat)

    Parton distribution functions from lattice QCD using Bayes-Gauss-Fourier transforms

    Constantia Alexandrou (Univ. of Cyprus and The Cyprus Inst.)🇨🇾 · Giovanni Iannelli (Univ. of Cyprus, Univ. of Rome Tor Vergata, Univ. of Humboldt Berlin and DESY-Zeuthen)🇨🇾 · Karl Jansen (DESY-Zeuthen)🇩🇪 · Floriano Manigrasso (Univ. of Cyprus, Univ. of Rome Tor Vergata and Univ. of Humboldt Berlin)🇨🇾

    We present a new method, based on Gaussian process regression, for reconstructing the continuous -dependence of parton distribution functions (PDFs) from quasi-PDFs computed using lattice QCD. We examine the origin of the unphysical oscillations seen in current lattice calculations of quasi-PDFs and develop a nonparametric fitting approach to take the required Fourier transform. The method is tested on one ensemble of maximally twisted mass fermions with two light quarks. We find that with our approach oscillations of the quasi-PDF are drastically reduced. However, the final effect on the light-cone PDFs is small. This finding suggests that the deviation seen between current lattice QCD results and phenomenological determinations cannot be attributed solely on the Fourier transform.

    Comments:
    Version accepted for PRD; 15 pages, 19 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2007.13800 [pdf]
    PRD(2020)·37 citations
  5. 05

    [Submitted on 28 Jul 2020] (cross-list from hep-ph)

    Light charged pion in ultra-strong magnetic field

    Jingyi Chao🇨🇳 · Yu-Xin Liu🇨🇳 · Lei Chang🇨🇳

    In this work, the mass of charged pions is investigated in the presence of background magnetic fields stronger than the energy scale of QCD. We introduce an anomaly magnetic momentum term in the Dirac equation and obtain the quark propagator as consequence. We find a novel finite Landau level, denoted as LL, becoming dominant rather than the conventional lowest Landau level. We examine that, due to the shifting of Landau level, it drives a mass decreasing around for charged pions and their masses drastically limit to the neutral one at ultra-strong magnetic field, , which is consistent with the recent lattice simulation.

    Comments:
    The assumption on the magnitude of the anomalous magnetic moment applied in this paper is hard to achieve
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2007.14258 [pdf]
    11 citations

Affiliations

first authorsco-authorsvia INSPIRE