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Nuclear Theory·nucl-th

Friday·January 13, 2023

3 papers—1 primary·2 cross-listed

All3Primary1Cross-lists2
  1. 01

    Wave-function-based emulation for nucleon-nucleon scattering in momentum space

    A. J. Garcia · C. Drischler · R. J. Furnstahl · J. A. Melendez · Xilin Zhang

    Emulators for low-energy nuclear physics can provide fast & accurate predictions of bound-state and scattering observables for applications that require repeated calculations with different parameters, such as Bayesian uncertainty quantification. In this paper, we extend a scattering emulator based on the Kohn variational principle (KVP) to momentum space (including coupled channels) with arbitrary boundary conditions, which enable the mitigation of spurious singularities known as Kohn anomalies. We test it on a modern chiral nucleon-nucleon (NN) interaction, including emulation of the coupled channels. We provide comparisons between a Lippmann-Schwinger equation emulator and our KVP momentum-space emulator for a representative set of neutron-proton (np) scattering observables, and also introduce a quasi-spline-based approach for the KVP-based emulator. Our findings show that while there are some trade-offs between accuracy and speed, all three emulators perform well. Self-contained Jupyter notebooks that generate the results and figures in this paper are publicly available.

    nucl-thhep-phphysics.data-anPRC(2023)·23 citations
  2. 02

    Refined theoretical values of field and mass isotope shifts in thallium to extract charge radii of Tl isotopes

    Gleb Penyazkov · Sergey D. Prosnyak · Anatoly E. Barzakh · Leonid V. Skripnikov

    Electronic factors for the field and mass isotope shifts in the (535 nm), (277 nm) and (378~nm) transitions in the neutral thallium were calculated within the high-order relativistic coupled cluster approach. These factors were used to reinterpret previous experimental isotope shift measurements in terms of charge radii of a wide range of Tl isotopes. Good agreement between theoretical and experimental King-plot parameters was found for the and transitions. It was shown that the value of the specific mass shift factor for the transition is not negligible compared to the value of normal mass shift in contrary to what had been suggested previously. Theoretical uncertainties in mean square charge radii were estimated. They were substantially reduced compared to the previously ascribed ones and amounted to less than 2.6%. The achieved accuracy paves the way to a more reliable comparison of the charge radii trends in the lead region.

    ↳ physics.atom-phnucl-thphysics.chem-phJ.Chem.Phys.(2023)·9 citations
  3. 03

    Charged pion electric polarizability from four-point functions in lattice QCD

    Frank X. Lee🇺🇸 · Andrei Alexandru🇺🇸 · Chris Culver🇬🇧 · Walter Wilcox🇺🇸

    Polarizabilities reveal valuable information on the internal structure of hadrons in terms of charge and current distributions. For neutral hadrons, the standard approach is the background field method. But for a charged hadron, its acceleration under the applied field complicates the isolation of the polarization energy. In this work, we explore an alternative method based on four-point functions in lattice QCD. The approach offers a transparent picture on how polarizabilities arise from photon, quark, and gluon interactions. We carry out a proof-of-concept simulation on the electric polarizability of a charged pion, using quenched Wilson action on a lattice at with pion mass from 1100 to 370 MeV. We show in detail the evaluation and analysis of the four-point correlation functions and report results on charge radius and electric polarizability. Our results from connected diagrams suggest that charged pion is due to a cancellation between elastic and inelastic contributions. It would be interesting to see how the cancellation plays out at smaller pion masses in future simulations.

    ↳ hep-latnucl-thPRD·14 citations

Affiliations

first authorsco-authorsvia INSPIRE