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Nuclear Theory·nucl-th

Monday·December 6, 2021

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 01

    [Submitted on 2 Dec 2021]

    Finite-temperature electron-capture rates for neutron-rich nuclei around N=50 and effects on core-collapse supernovae simulations

    S. Giraud · E. M. Ney · A. Ravlić · R.G.T. Zegers · J. Engel · N. Paar · B.A. Brown · J.-M. Gabler · J. Lesniak · J. Rebenstock

    The temperature dependence of stellar electron-capture (EC) rates is investigated, with a focus on nuclei around , just above , which play an important role during the collapse phase of core-collapse supernovae (CCSN). Two new microscopic calculations of stellar EC rates are obtained from a relativistic and a non-relativistic finite-temperature quasiparticle random-phase approximation approaches, for a conventional grid of temperatures and densities. In both approaches, EC rates due to Gamow-Teller transitions are included. In the relativistic calculation contributions from first-forbidden transitions are also included, and add strongly to the EC rates. The new EC rates are compared with large-scale shell model calculations for the specific case of Kr, providing insight into the finite-temperature effects on the EC rates. At relevant thermodynamic conditions for core-collapse, the discrepancies between the different calculations of this work are within about one order of magnitude. Numerical simulations of CCSN are performed with the spherically-symmetric GR1D simulation code to quantify the impact of such differences on the dynamics of the collapse. These simulations also include EC rates based on two parametrized approximations. A comparison of the neutrino luminosities and enclosed mass at core bounce shows that differences between simulations with different sets of EC rates are relatively small (), suggesting that the EC rates used as inputs for these simulations have become well constrained.

    Subjects:
    Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
    arXiv:
    2112.01626 [pdf]
    PRC(2022)·16 citations
  2. 02

    [Submitted on 3 Dec 2021]

    A comparison of two possible nuclear effective field theory expansions around the one- and two-pion exchange potentials

    Manuel Pavon Valderrama🇨🇳

    In the effective field theory formalism nuclear forces are organized as a low energy expansion. Usually the lowest order in this expansion corresponds to the non-perturbative iteration of the one-pion exchange potential and a few contact-range operators as to ensure renormalization group invariance. Here we consider an alternative expansion in which two-pion exchange becomes the lowest order finite range interaction and as such is expected to be iterated. A comparison of this new expansion with the standard one shows a better convergence pattern for a few selected partial waves (, and -) in two-nucleon scattering, in particular for the channel (though both expansions converge well). We briefly comment on the possible theoretical grounds for the expansion around two-pion exchange from the point of view of effective field theory.

    Comments:
    20 pages, 5 figures, 3 tables, explores what happens when TPE is not perturbative, corresponds to the version accepted in PRC
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2112.02076 [pdf]
    PRC(2025)·5 citations
  3. 03

    [Submitted on 1 Dec 2021] (cross-list from hep-ph)

    Phase structure of 2+1-flavour QCD and the magnetic equation of state

    Fei Gao🇩🇪 · Jan M. Pawlowski🇩🇪

    We determine the chiral phase structure of -flavour QCD in dependence of temperature and the light flavour quark mass with Dyson-Schwinger equations. Specifically, we compute the renormalised chiral condensate and its susceptibility. The latter is used to determine the (pseudo)critical temperature for general light current quark masses. In the chiral limit we obtain a critical temperature of about 141\,MeV. This result is in quantitative agreement with recent functional renormalisation group results in QCD, and is compatible with the respective lattice results. We also compute the order parameter potential of the light chiral condensate and map out the regime in the phase diagram which exhibits quasi-massless modes, and discuss the respective chiral dynamics.

    Comments:
    20 pages, 13 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2112.01395 [pdf]
    PRD(2022)·29 citations
  4. 04

    [Submitted on 3 Dec 2021] (cross-list from hep-lat)

    Most charming dibaryon near unitarity

    Yan Lyu🇨🇳 · Hui Tong🇨🇳 · Takuya Sugiura🇯🇵 · Sinya Aoki🇯🇵 · Takumi Doi🇯🇵 · Tetsuo Hatsuda🇯🇵 · Jie Meng🇨🇳 · Takaya Miyamoto🇯🇵

    We present a first study on a pair of triply charmed baryons, in the channel, on the basis of the HAL QCD method. The measurements are perfomed on the -flavor lattice QCD configurations with nearly physical light-quark masses and physical charm-quark mass. We show that the system with the Coulomb repulsion taking into account the charge form factor of leads to the scattering length fm and the effective range fm, which indicates is located in the unitary regime.

    Comments:
    8 pages, 4 figures, Talk presented at the 38th International Symposium on Lattice Field Theory, LATTICE2021, July, 26th-30th 2021, Zoom/Gather@Massachusetts Institute of Technology
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2112.01682 [pdf]
    PoS(2022)·5 citations
  5. 05

    [Submitted on 3 Dec 2021] (cross-list from hep-ph)

    Spin polarization dynamics in the non-boost-invariant background

    Wojciech Florkowski🇵🇱 · Radoslaw Ryblewski🇵🇱 · Rajeev Singh🇵🇱 · Gabriel Sophys🇵🇱

    Space-time evolution of spin polarization within the framework of hydrodynamics with spin based on de Groot - van Leeuwen - van Weert forms of energy-momentum and spin tensors is studied. Due to the non-boost invariant flow in the system the spin polarization components couple to each other implying some effects on the spin polarization observables. We study transverse-momentum and rapidity dependence of mean spin polarization vector for hyperons. Our results show qualitative agreement for rapidity dependence of the global spin polarization with the experiments and other models. The quadrupole structure of the longitudinal component at midrapidity is not found, however, as compared to the results for Bjorken expansion, some non-trivial signal at forward rapidities is observed.

    Comments:
    18 pages; 8 captioned figures; Comments are welcome; Matches with the published version: Phys. Rev. D 105, 054007 (2022)
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2112.01856 [pdf]
    PRD(2022)·50 citations
  6. 06

    [Submitted on 3 Dec 2021] (cross-list from quant-ph)

    Solving hadron structures using the basis light-front quantization approach on quantum computers

    Wenyang Qian🇪🇸 · Robert Basili🇺🇸 · Soham Pal🇺🇸 · Glenn Luecke🇺🇸 · James P. Vary🇺🇸

    Quantum computing has demonstrated the potential to revolutionize our understanding of nuclear, atomic, and molecular structure by obtaining forefront solutions in non-relativistic quantum many-body theory. In this work, we show that quantum computing can be used to solve for the structure of hadrons, governed by strongly-interacting relativistic quantum field theory. Following our previous work on light unflavored mesons as a relativistic bound-state problem within the nonperturbative Hamiltonian formalism, we present the numerical calculations on simulated quantum devices using the basis light-front quantization (BLFQ) approach. We implement and compare the variational quantum eigensolver (VQE) and the subspace-search variational quantum eigensolver (SSVQE) to find the low-lying mass spectrum of the light meson system and its corresponding light-front wave functions as quantum states from ideal simulators, noisy simulators, and IBM quantum computers. Based on obtained quantum states, we evaluate the meson decay constants and parton distribution functions directly on the quantum circuits. Our calculations on the quantum computers and simulators are in reasonable agreement with accurate numerical solutions solved on classical computers when noises are moderately small, and our overall results are comparable with the available experimental data.

    Comments:
    20 pages, 8 figures
    Subjects:
    Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
    arXiv:
    2112.01927 [pdf]
    PRResearch(2022)·47 citations

Affiliations

first authorsco-authorsvia INSPIRE