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Nuclear Theory·nucl-th

Wednesday·November 24, 2021

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 01

    Decision Theory for the Mass Measurements at the Facility for Rare Isotope Beams

    Jesse N. Farr · Zach Meisel · Andrew W. Steiner

    Nuclear physics facilities, like the Facility for Rare Isotope Beams (FRIB), can potentially perform many nuclear mass measurements of exotic isotopes. Each measurement comes with a particular cost, both in time and money, and thus it is important to establish which mass measurements are the most informative. In this article, we show that one can use the Kullback-Leibler divergence to determine the information gained by a mass measurement. We model the information gain obtained by nuclear mass measurements from two perspectives: first from the perspective of theoretical nuclear mass models, and the second from the perspective of r-process nucleosynthesis. While this work specifically analyzes the abilities of FRIB, other facilities worldwide could benefit from a similar use of information gain in order to decide which experiments are optimal.

    nucl-th4 citations
  2. 02

    Variational and parquet-diagram calculations for neutron matter. IV. Spin-orbit interactions and linear response

    E. Krotscheck · J. Wang

    We develop the parquet-diagram summation method for neutron matter interacting via potentials that include spin, tensor, and spin-orbit components. For that purpose, we derive an exact expression for the sum of all ring-diagrams in terms effective local particle-hole interactions involving the above four operators. The parquet equations are closed by deriving the spin-orbit contribution to that particle-hole interaction. We show that many-body correlations screen the bare spin-orbit potential considerably, and the corrections of that screened spin-orbit potential to the other three interaction channels are quite small. We apply our method to the calculation of the response of neutron matter to density and both longitudinal and transverse spin-dependent external fields.

    nucl-thPRC(2022)·8 citations
  3. 03

    On the Extraction of Low-energy Constants of Single- and Double- Decays from Lattice QCD: A Sensitivity Analysis

    Zohreh Davoudi🇺🇸 · Saurabh V. Kadam🇺🇸

    Lattice quantum chromodynamics (LQCD) has the promise of constraining low-energy constants (LECs) of nuclear effective field theories (EFTs) from first-principles calculations that incorporate the dynamics of quarks and gluons. Given the Euclidean and finite-volume nature of LQCD outputs, complex mappings are developed in recent years to obtain the Minkowski and infinite-volume counterparts of LQCD observables. In particular, as LQCD is moving toward computing a set of important few-nucleon matrix elements at the physical values of the quark masses, it is important to investigate whether the anticipated precision of LQCD spectra and matrix elements will be sufficient to guarantee tighter constraints on the relevant LECs than those already obtained from phenomenology, considering the non-trivial mappings involved. With a focus on the leading-order LECs of the pionless EFT, and , which parametrize, respectively, the strength of the isovector axial two-body current in a single- decay (and other related processes such fusion), and of the isotensor contact two-body operator in the neutrinoless double- decay within the light neutrino exchange scenario, the expected uncertainty on future extractions of and are examined using synthetic data at the physical values of the quark masses. It is observed that achieving small uncertainties in will be challenging, and (sub)percent-level precision in the two-nucleon spectra and matrix elements is essential in reducing the uncertainty on this LEC compared to the existing constraints. On the other hand, the short-distance coupling of the neutrinoless double- decay, , is shown to be less sensitive to uncertainties on both LQCD energies and the matrix element, and can likely be constrained with percent-level precision in the upcoming LQCD calculations.

    ↳ hep-lathep-phnucl-thPRD(2022)·35 citations
  4. 04

    Implications of NICER for neutron star matter: the QHC21 equation of state

    Toru Kojo🇨🇳 · Gordon Baym🇺🇸 · Tetsuo Hatsuda🇯🇵

    The recent NICER measurement of the radius of the neutron star PSR J0740+6620, and the inferred small variation of radii from 1.4 to 2.1, reveal key features of the equation of state of neutron star matter. The pressure rises rapidly in the regime of baryon density 2-4 times nuclear saturation density, -- the region where we expect hadronic matter to be undergoing transformation into quark matter -- and the pressure in the nuclear regime is greater than predicted by microscopic many-body variational calculations of nuclear matter. To incorporate these insights into the microscopic physics from the nuclear to the quark matter regimes, we construct an equation of state, QHC21, within the framework of quark-hadron crossover (QHC). We include nuclear matter results primarily based on the state-of-the-art chiral effective field theory, but also note results of using nuclear matter variational calculations based on empirical nuclear forces. We employ explicit nuclear degrees of freedom only up to , in order to explore the possibility of further physical degrees of freedom than nucleonic here. The resulting QHC21, which has a peak in sound velocity in -, is stiffer than the earlier QHC19 below 2, predicting larger radii in substantial agreement with the NICER data.

    ↳ astro-ph.HEhep-phnucl-thApJ(2022)·96 citations
  5. 05

    Improving the cold quark-matter pressure via soft interactions at N3LO

    Tyler Gorda🇩🇪

    The propagation of long-wavelength gluons through a dense QCD medium at high baryon chemical potential mu_B is qualitatively modified by the effects of screening, arising from scatterings off the high-momentum quarks in the medium. This same screening phenomenon also impacts gluons occurring in loop corrections to the pressure of cold quark matter, leading to contributions from the parametric scale Sqrt(alpha_s)*mu_B, starting at next-to-next-to-leading order (N2LO) in the strong coupling constant alpha_s. At next-to-next-to-next-to-leading order (N3LO), interactions between these long-wavelength gluonic modes contribute to the pressure. These interaction corrections have recently been computed in arXiv:2103.07427 and arXiv:2103.05658, and the inclusion of these interactions slightly improves the convergence of the equation of state of cold quark matter. In these proceedings, we present these results and provide details summarizing how this lengthy calculation was performed.

    ↳ hep-phnucl-thEPJ Web Conf.(2022)·0 citations
  6. 06

    Insignificance of the anomalous magnetic moment of the quarks in presence of chiral imbalance

    Nilanjan Chaudhuri🇮🇳 · Arghya Mukherjee🇮🇳 · Snigdha Ghosh🇮🇳 · Sourav Sarkar🇮🇳 · Pradip Roy🇮🇳

    We incorporate the anomalous magnetic moment (AMM) of quarks in the framework of PNJL model to study hot and dense magnetised matter with chiral imbalance. For this purpose, the eigen energy solution of the Dirac equation is obtained in presence of constant background magnetic field and chiral chemical potential (CCP) along with the minimal anomalous magnetic moment interaction of the fermion. Although there is a marginal enhancement in the IMC behaviour of the quark condensate due to the combined effects of AMM and CCP, we find that the overall behaviour of the Polyakov loop and the chiral charge density is dominated by the chiral chemical potential. It is further shown that the AMM effects in presence of CCP remains insignificant even after consideration of thermo-magnetically modified moments.

    ↳ hep-phnucl-thEPJA(2022)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE