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Nuclear Theory·nucl-th

Monday·June 11, 2018

8 papers—6 primary·2 cross-listed

All8Primary6Cross-lists2
  1. 01

    Energy Spectrum of Neutron-Rich Helium Isotopes: Complex Made Simple

    K. Fossez · J. Rotureau · W. Nazarewicz

    We demonstrate that the intricate energy spectrum of neutron-rich helium isotopes can be straightforwardly described by taking advantage of the low-energy properties of neutron-neutron interaction and the scale separation that is present in diluted dripline systems. By using arguments based on the halo effective field theory, we carry out a parameter reduction of the complex-energy configuration interaction framework in the space, including resonant and scattering states. By adjusting only one parameter, the strength of the spin-singlet central neutron-neutron interaction, we reproduce experimental energies and widths of He within tens of keV precision. We predict a parity inversion of narrow resonances in He and show that the ground state of He is an -wave-dominated threshold configuration that could decay through two-neutron emission.

    nucl-thPRC(2018)·35 citations
  2. 02

    'Running' under tight constraints in pionless effective field theory

    Jun-Jun Lü🇨🇳 · Ji-Feng Yang🇨🇳

    The contents of renormalization group invariance and equations under tight constraints are explored and demonstrated with closed-form on-shell matrices of pionless effective field theory for nuclear forces right within the effective field theory philosophy. The 'running' couplings under such tight constraints are presented in and uncoupled channels up to truncation order . Some linear relations are exposed and in turn employed in the pursuit of nonperturbative 'running' solutions which serves as an alternative choice without resorting to special prescription and additional operations or treatments. The utility of such 'running' behaviors inherent in the closed-form -matrices of pionless effective field theory is remarked and a number of important issues related to effective field theory constructed with various truncations are interpreted or discussed from the underlying theory perspective.

    nucl-thhep-phIJMPE(2021)·1 citation
  3. 03

    Heavy-ion double-charge-exchange and its relation to neutrinoless double-beta decay

    E. Santopinto🇮🇹 · H. García-Tecocoatzi🇮🇹 · R.I. Magaña-Vsevolodovna🇮🇹 · J. Ferretti🇨🇳

    We introduce the formalism to describe heavy-ion Double-Charge-Exchange (DCE) processes in the eikonal approximation. We focus on the low-momentum-transfer limit -- corresponding to the differential cross section at -- and, for the first time, we show that it is possible to factorize the DCE cross-section in terms of reaction and nuclear parts. Whereas in the case the nuclear part is a convolution of the beam and target nuclear matrix elements (NMEs), for we demonstrate - for the first time- that the transition matrix elements can be written as the sum of Double-Gamow-Teller (DGT) and Double Fermi (DF) type parts, and that they can both be further factorized in terms of target and projectile NMEs. By making use of the Interacting Boson Model (IBM) formalism, we also show that the DGT and total parts of the neutrinoless double-beta decay NMEs are in linear correlation with DCE-DGT NMEs. This confirms the hypothesis of a linear correlation between them, as introduced in [Phys.\ Rev.\ Lett.\ {\bf 120}, 142502 (2018)]. The possibility of a Two-Step Factorization (TSF) of the very forward differential DCE-cross-section and the emergence of DGT and DF types for the DCE nuclear matrix elements, combined with a linear correlation between DCE-DGT and 0 NMEs, opens the possibility of placing an upper limit on neutrinoless double-beta decay NMEs in terms of the DCE experimental data at .

    nucl-thPRC(2018)·78 citations
  4. 04

    Ab initio calculation of nuclear structure corrections in muonic atoms

    Chen Ji🇨🇳 · Sonia Bacca🇩🇪 · Nir Barnea🇮🇱 · Oscar Javier Hernandez🇩🇪 · Nir Nevo-Dinur🇨🇦

    The measurement of the Lamb shift in muonic hydrogen and the subsequent emergence of the proton-radius puzzle have motivated an experimental campaign devoted to measuring the Lamb shift in other light muonic atoms, such as muonic deuterium and helium. For these systems it has been shown that two-photon exchange nuclear structure corrections are the largest source of uncertainty and consequently the bottleneck for exploiting the experimental precision to extract the nuclear charge radius. Utilizing techniques and methods developed to study electromagnetic reactions in light nuclei, recent calculations of nuclear structure corrections to the muonic Lamb shift have reached unprecedented precision, reducing the uncertainty with respect to previous estimates by a factor of 5 in certain cases. These results will be useful for shedding light on the nature of the proton-radius puzzle and other open questions pertaining to it. Here, we review and update calculations for muonic deuterium and tritium atoms, and for muonic helium-3 and helium-4 ions. We present a thorough derivation of the formalism and discuss the results in relation to other approaches where available. We also describe how to assess theoretical uncertainties, for which the language of chiral effective field theory furnishes a systematic approach that could be further exploited in the future.

    nucl-thphysics.atom-phJ.Phys.G(2018)·51 citations
  5. 05

    Comment on "Measurement of the Dependence of the Deuteron Spin Structure Function and its Moments at Low with CLAS"

    Vadim Lensky🇩🇪 · Franziska Hagelstein🇨🇭 · Astrid Hiller Blin🇩🇪 · Vladimir Pascalutsa🇩🇪

    We argue that the recently published CLAS results on the deuteron spin polarizability [Adhikari {\it et al.}, Phys.\ Rev.\ Lett.\ {\bf 120}, 062501 (2018)], as well as their comparisons with chiral perturbation theory (PT), are misleading. In reality, the deuteron polarizability is larger by 4 orders of magnitude, as demonstrated here by a novel calculation in pionless EFT. The CLAS paper, on the other hand, presents only a tiny correction to it, based on a partial evaluation of a sum rule for . The sum rule is assumed to have the same form as for the nucleon; we argue it does not. Moreover, their "test of PT" tacitly involves assumptions which, as we demonstrate, may not be valid at the claimed accuracy.

    nucl-thhep-phnucl-ex4 citations
  6. 06

    Extended Skyrme interactions for transport model simulations of heavy-ion collisions

    Rui Wang🇨🇳 · Lie-Wen Chen🇨🇳 · Ying Zhou🇨🇳

    Based on an extended Skyrme interaction that includes the terms in relative momenta up to sixth order, corresponding to the so-called Skyrme pseudopotential up to next-to-next-to-next-to leading order (N3LO), we derive the expressions of Hamiltonian density and single nucleon potential under general non-equilibrium conditions which can be applied in transport model simulations of heavy-ion collisions induced by neutron-rich nuclei. While the conventional Skyrme interactions, which include the terms in relative momenta up to second order, predict an incorrect behavior as a function of energy for nucleon optical potential in nuclear matter, the present extended N3LO Skyrme interaction can give a nice description for the empirical nucleon optical potential. We also construct three interaction sets with different high-density behaviors of the symmetry energy, by fitting both the empirical nucleon optical potential up to energy of GeV and the empirical properties of isospin asymmetric nuclear matter. These extended N3LO Skyrme interactions will be useful in transport model simulations of heavy-ion collisions induced by neutron-rich nuclei at intermediate and high energies, and they can also be useful in nuclear structure studies within the mean-field model.

    nucl-thastro-ph.SRhep-phnucl-exPRC(2018)·31 citations

Affiliations

first authorsco-authorsvia INSPIRE