• Introduction
• Theory Roadmap
• Highlights
• Summary
Perspectives on Nuclear Structure Theory
Witold Nazarewicz (Tennessee)
ACS National Meeting Atlanta March 2006
The ultimate g oal of the physics of
nuclei is to
develop a unif ied, predictive the ory
of nucleonic m atter
Questions that Drive the Field (see RIA Brochure)
• How do protons and neutrons make stable nuclei and rare isotopes?
• What is the origin of simple patterns in complex nuclei?
• What is the equation of state of matter made of nucleons?
• What are the heaviest nuclei that can exist?
• When and how did the elements from iron to uranium originate?
• How do stars explode?
• What is the nature of neutron star matter?
• Why is there more matter than antimatter?
• What are the weak interactions among hadrons, and how are they affected by the nucleus?
• What are the masses of neutrinos and how have they shaped the evolution of the universe?
• How can our knowledge of nuclei and our ability to produce them benefit the humankind?
– Life Sciences – Material Sciences – Nuclear Energy – Security
Physics of nuclei
Nuclear
astrophysics
Fundamental interactions
& neutrinos
Applications of nuclei
Theory plays crucial role
•complements experiment
•provides vision
•provides deeper understanding
•provides intellectual motivation
Theory plays crucial role
•complements experiment
•provides vision
•provides deeper understanding
•provides intellectual
motivation
Overarching goal:
• This is a lofty and ambitious goal that has been a
“Holy Grail” in physics for over fifty years
• “Unified” does not mean that there is a single theoretical method that will work in all cases
– Self-bound, two-component quantum many-fermion system – Complicated interaction based on QCD with at least
two- and three-nucleon components
– We seek to describe the properties of “nuclei”
ranging from the deuteron to neutron stars
Nuclear Structure Theory Nuclear Structure Theory
To arrive at a comprehensive and unified microscopic
description of all nuclei and there low-energy reactions from the the basic interactions between the constituent protons and neutrons
There is no “one size fits all” theory for nuclei, but all our theoretical approaches need to be linked by an underlying use of the constituents and the interactions between them
E. Ormand, RISAC, Irvine 2006
• Effective-field theory potentials
• Effective-field theory potentials
Nuclear Structure: the interaction Nuclear Structure: the interaction
•Quality two- and three- nucleon interactions exist
•The challenge is to
understanding how to use them in nuclei
•Quality two- and three- nucleon interactions exist
•The challenge is to
understanding how to use them in nuclei
N3LO: Entem et al., PRC68, 041001 (2003)
Parameters for EFT three-nucleon interaction
Best EFT three- nucleon potential
Bottom-up approaches to nuclear structure Bottom-up approaches to nuclear structure
Ab initio
Configuration interaction Density Functional Theory
Theoretical approaches overlap and need to be bridged
Theoretical approaches overlap and need to be bridged
Roadmap
Collective and
Algebraic Models
(top-down)
Ab initio: GFMC, NCSM, CCM
(nuclei, neutron droplets, nuclear matter)
S. Pieper, ENAM’04
1-2% calculations of A = 6 – 12 nuclear energies are possible
excited states with the same quantum numbers computed
Ab Initio Nuclear Structure Theory
(with bare NN+NNN interactions)
Quantum Monte Carlo (GFMC)
12C
No-Core Shell Model
13C
Coupled-Cluster Techniques
16O
Unitary Model Operator Approach
Faddeev-Yakubovsky
Bloch-Horowitz
… Input:
Excellent forces based on the phase shift analysis (can be unified through V
low k) Realistic NNN interactions
EFT based nonlocal chiral NN and NNN potentials
Challenges:
Interaction: NNN (How important is NNNN?)
How to extend calculations to heavier systems?
Treatment of weakly-bound and unbound states, and cluster correlations
Diagonalization Shell Model
(medium-mass nuclei reached;dimensions 10
9!)
Martinez-Pinedo ENAM’04
10
24is not an option!!!!
Smarter solutions are needed
Challenges:
Configuration space
Effective Interactions
Open channels
Coupling of nuclear
structure and reaction theor y
(microscopic treatment of
open channels)
Nuclear DFT
From Qualitative to Quantitative!
Deformed Mass Table in one day!
Old paradigms, universal ideas, are not correct
Near the drip lines nuclear structure may be dramatically different.
No shell closure for N=8 and 20 for drip-line nuclei; new shells at 14, 16, 32…
First experimental indications demonstrate significant changes
€
S n = −ε F − Δ
S 2n = −2ε F
Ab Initio
What are the missing pieces?
Shell Model
Density Functional Theory
What are the limits of atoms and nuclei?
Do very long-lived superheavy nuclei exist?
What are their physical and chemical properties?
Three frontiers, relating to the determination of the proton and neutron drip lines far beyond present knowledge, and to the synthesis of the heaviest elements
lifetimes > 1y
What are the limits of atoms and nuclei?
What are the limits of nuclear
mean field?
Skins and Skin Modes
p p
n n n n
p p n n n n p p
n n
n n
Collective or single-particle?
Skin effect? Threshold effect?
Energy differential electromagnetic
dissociation cross section Deduced photo-neutron
cross section.
LAND-FRS
Q 1 Q
E
shapecoexistence shape
coexistence
Q 2
Q 0 Q E
fission/fusionexotic decay heavy ion coll.
fission/fusion exotic decay heavy ion coll.
M. Bender et al., PRC 69, 064303 (2004)
GCM
Shape coexistence
Beyond Mean Field
nuclear collective dynamics
Challenges:
•selection of appropriate degrees of freedom
•simultaneous treatment of symmetry
•coupling to continuum in weakly bound systems
•dynamical corrections; fundamental theoretical problems.
•rotational, vibrational, translational
•particle number
•isospin
Variety of phenomena:
•symmetry breaking and quantum corrections
•LACM: fission, fusion, coexistence
•phase transitional behavior
•new kinds of deformations
Significant computational resources required:
•Generator Coordinate Method
•Projection techniques
•Imaginary time method (instanton techniques)
•QRPA and related methods
•TDHFB, ATDHF, and related methods
( 3 He,p)
N=Z line
Measure the np transfer cross section to T=1 and T=0 states Both absolute (T=0) and (T=1) and relative (T=0) / (T=1) tell us about the character and strength of the correlations Measure the np transfer cross section to T=1 and T=0 states Both absolute (T=0) and (T=1) and relative (T=0) / (T=1) tell us about the character and strength of the correlations