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Nuclear Theory·nucl-th

Friday·March 5, 2021

4 papers—2 primary·2 cross-listed

All4Primary2Cross-lists2
  1. 01

    [Submitted on 4 Mar 2021]

    Measurement methods of radial flow in relativistic heavy-ion collisions

    Peng Yang🇨🇳 · Lin Li🇨🇳 · Yu Zhou🇺🇸 · Zhiming Li🇨🇳 · Mingmei Xu🇨🇳 · Yeyin Zhao🇨🇳 · Yuanfang Wu🇨🇳

    Radial flow can be directly extracted from the azimuthal distribution of mean transverse rapidity. We apply the event-plane method and the two-particle correlation method to estimate the anisotropic Fourier coefficient of the azimuthal distribution of mean transverse rapidity. Using the event sample generated by a multiphase transport model with string melting, we show that both methods are effective. For the two-particle correlation method to be reliable, the mean number of particles in an azimuthal bin must be above a certain threshold. Using these two methods, anisotropic radial flow can be estimated in a model-independent way in relativistic heavy-ion collisions.

    Comments:
    8 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2103.02869 [pdf]
    PRC(2021)·1 citation
  2. 02

    [Submitted on 4 Mar 2021]

    Neutron-neutron scattering length from the He reaction

    Matthias Göbel · Thomas Aumann · Carlos A. Bertulani · Tobias Frederico · Hans-Werner Hammer · Daniel R. Phillips

    We propose a novel method to measure the neutron-neutron scattering length using the He reaction in inverse kinematics at high energies. The method is based on the final state interaction (FSI) between the neutrons after the sudden knockout of the particle. We show that the details of the neutron-neutron relative energy distribution allow for a precise extraction of the -wave scattering length. We present the state-of-the-art in regard to the theory of this distribution. The distribution is calculated in two steps. First, we calculate the ground-state wave function of He as a three-body system. For this purpose we use Halo effective field theory (Halo EFT), which also provides uncertainty estimates for the results. We compare our results at this stage to model calculations done with the computer code FaCE. In a second step we determine the effects of the FSI using the t-matrix. We compare these FSI results to approximate FSI approaches based on standard FSI enhancement factors. While the final distribution is sensitive to the scattering length, it depends only weakly on the effective range. Throughout we emphasize the impact of theoretical uncertainties on the neutron-neutron relative energy distribution, and discuss the extent to which those uncertainties limit the extraction of the neutron-neutron scattering length from the reaction He.

    Comments:
    Paper + supplemental material: 20+11 pages, 7+4 figures. Paper restructured, further explanations and discussions added, results unchanged. Accepted for publication in Phys. Rev. C
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2103.03224 [pdf]
    PRC(2021)·18 citations

Affiliations

first authorsco-authorsvia INSPIRE