User Tools

Site Tools


wiki:structure_reaction_methods

Structure and Reaction Inputs and Methods

The talks linked here were given at the Light Nuclei from First Principles workshop. They are listed under multiple headings as appropriate.

Inputs

Chiral EFT Hamiltonians and operators

New and ongoing developments

  • 3N interaction at N3LO, N4LO
  • explicit inclusion of Delta resonance
  • including strange baryons
  • formal issues: renormalization, …

Hermann Krebs: "Chiral three-nucleon forces up to N4LO"

Robert Roth: "Chiral Three-Nucleon Interactions and the Structure of Light Nuclei"

Softened Hamiltonians and operators
Argonne V18 and Illinois 3NF interactions
  • Although fit to 350 MeV, many partial waves are (semi-)quantitatively correct up to 600 MeV.

Bob Wiringa: "Recent results from nuclear quantum Monte Carlo"


Methods

For each method, what are (now and projected):

  • Nuclei accessible
  • Observables accessible
  • Validation methods (e.g., benchmarks against other methods)
  • Error analysis
Lattice EFT

Over the next decade, the lattice effective field theory community will focus on ab initio calculations of nuclear structure for up to A = 28, astrophysical capture reactions, nucleus-nucleus scattering, weak decay rates, and properties of the neutron crust. In particular we plan to calculate proton and alpha capture rates, beta decay rates, scattering phase shifts, resonance widths, S-wave and P-wave pairing in neutron matter, and properties of nuclei in neutron superfluids. [Dean Lee]

Ulf Meißner: "Testing the Anthropic Principle with Lattice Simulations"

Other EFT approaches
No-Core Shell Model (and variations)

Hamiltonian diagonalization method to produce low-lying energy eigenvalues and corresponding wave functions.

New and on-going Developments

  • Importance Truncated NCSM

High precision calculations of light nuclei up to A about 50 (spectra, moments, excitation functions, decays, reactions, etc.) with next-generation chiral EFT interactions complete through N3LO will be carried out to answer the question of whether we finally have a “standard model” of low-energy nuclear physics. Such calculations would include no core shell model (NCSM, IT-NCSM), no core full configuration (NCFC), no core monte-carlo shell model (NC-MCSM) and NCSM with a core in order to reach the widest range of nuclei with the highest precision to form these critical tests. Both “delta-less” and “delta-full” versions will be used to determine which provides the highest accuracy and fastest convergence rates. In parallel with these investigations, neutron drops will be solved in various external fields to help develop next-generation energy-density functionals for applications to heavier nuclei, nuclei at the extremes of neutron to proton ratios and the neutron matter equation of state. Finally, we will test fundamental symmetries in nature with these Hamiltonians and many-body methods by performing calculations of neutrinoless double beta-decay, for example. [James Vary]

Pieter Maris: "Ab initio calculations of Be isotopes with JISP16

Robert Roth: "Chiral Three-Nucleon Interactions and the Structure of Light Nuclei"

Ab-inito Reactions with NCSM/RGM

Over the next decade, the NCSM/RGM approach and its generalization, the no-core shell model with continuum, will be capable to provide a realistic description of low-energy (up to 5-20 MeV) binary cluster reactions with projectiles up to 4He and p- or light sd-shell targets, as well as light Borromean nuclei and reactions with three clusters in the final state. This capability will include the description of scattering, transfer, fusion, capture reactions relevant to astrophysics, brehmsstrahlung, and low-lying structure of light exotic nuclei based on realistic interactions derived from QCD. [Petr Navratil and Sofia Quaglioni]

Sofia Quaglioni: "Ab initio calculations of light-ion fusion reactions"

Petr Navratil: "Ab initio description of the unbound 7He"

Coupled Cluster

The coupled-cluster method is ideal for studies of semi-magic nuclei and their neighbors. Over the next decade, we aim at describing the structure (binding energies, spectra, radii and EM transition rates) of neutron-rich nuclei such as calcium isotopes beyond Ca-60, nuclei around Ni-78, and around Sn-132 with the coupled-cluster method. We have taken first steps in computing elastic scattering of nucleons off doubly magic nuclei, and plan to extend this approach to nucleon transfer reactions involving semi-magic nuclei. Finally, we plan to study weak properties (beta decay, double-beta decay of Ca-48, computation of weak charges). [Thomas Papenbrock]

Gaute Hagen: "Living at the edge of stability: The role of continuum and three-nucleon forces"

Robert Roth: "Chiral Three-Nucleon Interactions and the Structure of Light Nuclei"

Quantum Monte Carlo (Variational andGFMC)

(From Bob's talk) * Calculate binding energies, excitatin spectra, relative stability * Densities, electromagnetic moments, transition amplitudes, cluster-cluster overlaps * Low-energy NA …

Bob Wiringa: "Recent results from nuclear quantum Monte Carlo"

Stefano Gandolfi: "Properties of neutron matter, symmetry energy and neutron stars"

Many-Body Perturbation Theory for the Shell Model

Over the next decade, we will advance our understanding and predictions for neutron-rich and proton-rich nuclei based on chiral effective field theory interactions (NN, 3N and 4N) within the shell model across the full sd and pf shell and to heavier regions key to astrophysics, such as the Z=50 and N=82 region along the r-process path. Advances will include the development of nonperturbative effective interaction methods (e.g., with the IMSRG), the inclusion of the continuum, and the interface with energy density functionals for global mass predictions. This will provide spectroscopic information, masses and input for reactions over a broad range for astrophysics, in parallel to calculations and constraints for the nuclear equation of state and for neutrino rates based on the same chiral effective field theory interactions. [Achim Schwenk]

Through more controlled calculations of valence space interactions with in-medium SRG, combined with coupling to the continuum, over the next decade non-empirical shell model will probe with increasing accuracy medium and heavy-mass nuclei with extreme neutron-to-proton ratios near and beyond the limits of stability. In addition to ground and excited state properties, a microscopic treatment of electromagnetic and nuclear weak processes, including neutrinoless double-beta decay, are in progress. One long-term aim will be systematic studies of nuclei relevant for understanding nucleosynthesis processes possibly responsible for the creation of heavy elements in the universe, particularly the r-process, where many of the very neutron-rich nuclei of interest will not be produced in even newest generation rare-isotope facilities. [Jason Holt]

Jason Holt: "Three nucleon forces and the structure of exotic nuclei"

Achim Schwenk: "Three-nucleon forces and the evolution towards the driplines"

Robert Roth: "Chiral Three-Nucleon Interactions and the Structure of Light Nuclei"

Kai Hebeler: "Momentum-space evolution of chiral three-nucleon forces"

In-Medium Similarity Renormalization Group (IM-SRG)

In the next decade, IM-SRG will be able to provide ab initio predictions for ground- and excited state properties of closed- and open-shell nuclei (at least) up to the tin isotopic chain (complete treatment of sdg-shell + h_11/2 intruder state), including binding energy systematics along isotopic and isotonic chains, information about pairing gaps/binding energy differences, transition rates and densities for transition operators of interest (via the evolution of observables), etc.. The uncertainties associated with the method are under controlled, an on the order of a few %, hence the overall uncertainties will be dominated by the input Hamiltonians and transition operators form, e.g., chiral EFT. By the latter part of the decade, we expect the capability to carry out detailed analyses for deformed nuclei as well. Given the positive experiences with the flow equation approach in condensed matter physics, we do not anticipate major obstacles to completing initial developments of a finite-temperature IM-SRG by the end of the decade. [Heiko Hergert]

Heiko Hergert: "In-Medium SRG for Finite Nuclei"

Fermionic Molecular Dynamics (FMD)
Self-Consistent Green's Function
wiki/structure_reaction_methods.txt · Last modified: 2013/01/10 17:47 (external edit)