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Nuclear Theory·nucl-th

Thursday·November 12, 2020

10 papers—3 primary·7 cross-listed

All10Primary3Cross-lists7
  1. 01

    [Submitted on 11 Nov 2020]

    Strangeness and baryon-baryon interactions in relativistic chiral effective field theory

    Zhi-Wei Liu🇨🇳 · Jing Song🇨🇳 · Kai-Wen Li🇨🇳 · Li-Sheng Geng🇨🇳

    The strangeness and baryon-baryon interactions are investigated in the relativistic chiral effective field theory at leading order. First, the potentials are derived from the sector assuming that the corresponding low-energy constants are related to each other via SU(3) flavor symmetry. The comparison with the state-of-the-art lattice QCD simulations, show, however, that SU(3) flavor symmetry breaking effects can not be neglected. In order to take into account these effects, we redetermine two sets of low-energy constants by fitting to the lattice QCD data in the and channels respectively. The fitting results demonstrate that the lattice QCD -waves phase shifts for both channels can be described rather well. Without any additional free low-energy constants, the predicted phase shifts for the channel and the mixing angle are also in qualitative agreement with the lattice QCD data for the channel, while the results for the channel remain to be checked by future lattice QCD simulations. With the so-obtained low-energy constants, the -wave scattering lengths and effective ranges are calculated for these two channels at the physical point. Finally, in combination with the and results obtained in our previous works, we study the evolution of the irreducible representation in the baryon-baryon interactions as a function of increasing strangeness. It is shown that the attraction decreases dramatically as strangeness increases from to , but then remains relatively stable until . The results indicate that the existence of bound states in the and channels is rather unlikely.

    Comments:
    9 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2011.05510 [pdf]
    PRC(2021)·22 citations
  2. 02

    [Submitted on 11 Nov 2020]

    The subtle connection between shape coexistence and quantum phase transition. The Zr case

    J.E. García-Ramos · K. Heyde

    Background: Zr region is characterized by very rapid changes in the ground state structure of the nuclei. In particular, the onset of deformation when passing from Zr to Zr is one of the fastest ever observed in the nuclear chart. It has been probed both experimental and theoretically that certain low-lying excited states of Zr isotopes own different shapes than the ground state. Purpose: We intend to disentangle the interplay between the sudden changes in the ground state shape, i.e., the existence of a quantum phase transition, and the presence in the spectra of coexisting states with very different deformation, i.e., the presence of shape coexistence. Method: We rely on a previous calculation using the Interacting Boson Model with Configuration Mixing (IBM-CM) which reproduces in detail the spectroscopic properties of Zr. This IBM-CM calculation allows to compute mean-field energy surfaces, wave functions and any other observable related with the presence of shape coexistence or with a quantum phase transition. Results: We obtain energy surfaces and the equilibrium value of the deformation parameter , the U(5) decomposition of the wave functions and the density of states. Conclusions: We confirm that Zr is a clear example of quantum phase transition that originates from the crossing of two configurations with a very different degree of deformation. Moreover, we observe how the intruder configuration exhibits its own evolution which resembles a quantum phase transition too.

    Comments:
    Accepted in Physical Review C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2011.05581 [pdf]
    PRC(2020)·32 citations
  3. 03

    [Submitted on 11 Nov 2020]

    Neutron matter at finite temperature based on chiral effective field theory interactions

    J. Keller · C. Wellenhofer · K. Hebeler · A. Schwenk

    We study the equation of state of neutron matter at finite temperature based on two- and three-nucleon interactions derived within chiral effective field theory to next-to-next-to-next-to-leading order. The free energy, pressure, entropy, and internal energy are calculated using many-body perturbation theory including terms up to third order around the self-consistent Hartree-Fock solution. We include contributions from three-nucleon interactions without employing the normal-ordering approximation and provide theoretical uncertainty estimates based on an order-by-order analysis in the chiral expansion. Our results demonstrate that thermal effects can be captured remarkably well via a thermal index and a density-dependent effective mass. The presented framework provides the basis for studying the dense matter equation of state at general temperatures and proton fractions relevant for core-collapse supernovae and neutron star mergers.

    Comments:
    14 pages, 14 figures, minor changes, published version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
    arXiv:
    2011.05855 [pdf]
    PRC(2021)·66 citations

Affiliations

first authorsco-authorsvia INSPIRE