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Nuclear Theory·nucl-th

Wednesday·June 16, 2021

5 papers—2 primary·3 cross-listed

All5Primary2Cross-lists3
  1. 01

    [Submitted on 15 Jun 2021]

    Probing early-time longitudinal dynamics with the hyperon's spin polarization in relativistic heavy-ion collisions

    Sangwook Ryu🇺🇸 · Vahidin Jupic🇺🇸 · Chun Shen🇺🇸

    We systematically study the hyperon global polarization's sensitivity to the collision systems' initial longitudinal flow velocity in hydrodynamic simulations. By explicitly imposing local energy-momentum conservation when mapping the initial collision geometry to macroscopic hydrodynamic fields, we study the evolution of systems' orbital angular momentum (OAM) and fluid vorticity. We find that a simultaneous description of the hyperons' global polarization and the slope of pion's directed flow can strongly constrain the size of longitudinal flow at the beginning of hydrodynamic evolution. We extract the size of the initial longitudinal flow and the fraction of orbital angular momentum in the produced QGP fluid as a function of collision energy with the STAR measurements in the RHIC Beam Energy Scan program. We find that there is about 100-200 OAM that remains in the mid-rapidity fluid at the beginning of hydrodynamic evolution. We further exam the effects of different hydrodynamic gradients on the spin polarization of and . The gradients of can change the ordering between 's and 's polarization.

    Comments:
    update in accordance with the referee report
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2106.08125 [pdf]
    PRC(2021)·100 citations
  2. 02

    [Submitted on 15 Jun 2021]

    Imprints of high-momentum nucleons in nuclei on hard photons from heavy-ion collisions around the Fermi Energy

    Wen-Mei Guo🇨🇳 · Bao-An Li🇺🇸 · Gao-Chan Yong🇨🇳

    The short-range correlation (SRC) induced by the tensor force in the isosinglet neutron-proton interaction channel leads to a high-momentum tail (HMT) in the single-nucleon momentum distributions n(k) in nuclei. Owing to the remaining uncertainties about the tensor force, the shape of the nucleon HMT may be significantly different from the dilute interacting Fermi gas model prediction similar to the HMT in cold atoms near the unitary limit. Within an isospin- and momentum-dependent Boltzmann-Uehling-Uhlenbeck transport model incorporating approximately the nucleon HMT, we investigate hard photon emissions in N+C and Ca+Sn reactions at beam energies around the Fermi energy. Imprints of different shapes of the HMT on the energy spectrum, angular distribution and transverse momentum spectrum of hard photons are studied. While the angular distribution does not carry any information about the shape of the nucleon HMT, the energy spectra and especially the mid-rapidity transverse momentum spectra of hard photons are found to bare strong imprints of the shapes of nucleon HMTs in the two colliding nuclei.

    Comments:
    More discussions added. Physical Review C in press
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2106.08242 [pdf]
    PRC(2021)·37 citations

Affiliations

first authorsco-authorsvia INSPIRE