Theoretical challenges in the physics of nuclei

1
Theoretical challenges in the physics of
nuclei Witold Nazarewicz (Tennessee) The DNP town
meeting on Nuclear Astrophysics/Study of
Nuclei Chicago, Jan. 19-21, 2007

• The TM organizers requested to address the
  following questions
• Identify the major accomplishments in your area
  since the last long range plan
• What has been the impact of this progress within
  and outside of the field?
• Identify the most compelling scientific questions
  and opportunities for the next decade (within US)
  and their scientific impact
• What facilities and other resources are needed
  for realizing these opportunities?
• A "lower cost" version of an advanced Rare
  Isotope facility is explicitly mentioned in the
  charge as the main major new facility for our
  area compatible with projected funding levels.
  What role does this facility play in realizing
  the major future opportunities in the area you
  are covering?
• What other needs does your field have until this
  new facility is operational?
• What will be the scientific impact on other
  fields, are there interdisciplinary aspects?

2

• Input solicited Dec. 18 (RIATG) and Jan. 9
  (speakers)
• A number of suggestions received
• Thanks!!!
• Other useful sources
• NSAC Theory Report
• RIATG Blue Book
• RIA Brochure
• RISAC report
• Various talks, presentations, papers

• Disclaimer
• Not every excellent work/piece of research from
  2002-2006 can be highlighted in a 25 min. talk
• No pictures, no names (for MANY pictures/names,
  see Nuclear Theory session)
• Only selected/representative references, for the
  benefit of the writing committee
• The focus of this talk is on the questions posed
  by the Town Meeting Organizers

3
Theory of Nuclei

• Overarching goal
• 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 finite and
  bulk nucleonic matter ranging from the deuteron
  to neutron stars and nuclear matter including
  strange matter
• We want to be able to extrapolate to unknown
  regions

To arrive at a comprehensive and unified
microscopic description of all nuclei and
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. We are making great progress in
this direction.
4
Weinbergs Laws of Progress in Theoretical
Physics From Asymptotic Realms of Physics (ed.
by Guth, Huang, Jaffe, MIT Press, 1983)
First Law The conservation of Information (You
will get nowhere by churning equations) Second
Law Do not trust arguments based on the lowest
order of perturbation theory Third Law You
may use any degrees of freedom you like to
describe a physical system, but if you use the
wrong ones, youll be sorry!
D. Furnstahl, INT Fall05
5
2002-2006 very successful period for theory of
nuclei

• many new ideas leading to new understanding
• new theoretical frameworks
• exciting developments
• high-quality calculations

• The nucleon-based description works to
• Effective Field Theory/Renormalization Group
  provides missing links
• Accurate ab-initio methods allow for interaction
  tests
• Quantitative microscopic nuclear structure
• Integrating nuclear structure and reactions
• High-performance computing continues to
  revolutionize microscopic nuclear many-body
  problem impossible becomes possible

6
Roadmap QCD?EFT ?ab-initio?effective many-body
methods ??modern theory of LACM and nuclear
reactions
Collective and Algebraic Models (top-down)
Theoretical approaches overlap and need to be
bridged
7
A. Richter, INPC 2004
A cooperative and coherent effort running from
QCD through the heaviest nuclei
8
Identify the major accomplishments in your area
since the last long range plan I. Science
Hard evidence of the progress!

• Development of chiral interactions NN PRC 68,
  041001(R)(2003) NNN PRC 66, 064001 (2002)
• First fully dynamical lattice QCD calculation of
  the S-wave NN scattering lengths conducted with
  pion masses of 350 MeV and larger PRL 97, 012001
  (2006)
• Renormalization Group (RG) method used to produce
  universal low-momentum interaction Vlow-k PRC
  70, 061002(R) (2004) Phys. Rep. 386, 1 (2003)
• GFMC calculations for 12C and excited states of
  light nuclei NPA 751, 516c (2005) and EM response
  in light systems PRC 65, 024002 (2002)
• Quantum Monte Carlo description of 1S0 pairing in
  nuclear matter with NN and NNN PRL 95,192501
  (2005)
• No-core Shell Model calculations for light nuclei
  with chiral NN and NNN forces PRC 73, 064002
  (2006)
• Coupled Cluster calculations for light and
  medium-mass nuclei PRL 92, 132501 (2004)
• Ab-initio description of nuclear reactions GFMC
  nucl-th/0612035, NCSM PRC 73, 065801 (2006) CC
  nucl-th/060072
• Explicit RG demonstration that high-energy
  details in wave functions and operators are
  irrelevant to low-energy observables
  nucl-th/0701013
• Demonstration that conventional nuclear physics
  explains polarization observables in
  4He(e,ep)3H no need to modify the proton in
  nuclear environment PRL94, 072303 (2005)
• Correlations in asymmetric nuclear matter,
  spectral functions PRC 71, 014313 (2005) PPNP
  52, 377 (2004)
• Global Shell Model description of pf nuclei PRC
  69, 034335 (2004)
• Unification of structure and reactions -
  development of modern continuum SM approaches
  GSM PRL 89, 042502 (2002) CSM PRL 94, 052501
  (2005) SMEC NPA 767, 13 (2006)

9
Science accomplishments (cont.)

• Towards universal nuclear density functional
• Microscopic DFT mass table PRC 66, 024326
  (2002), PRC 68, 054312 (2003)
• Constraints on time-odd fields PRC 65, 054322
  (2002)
• Microscopic (GCMproj) zero-point correlation
  energies and 2 states PRC 73, 034322 (2006)
  nucl-th/0611089 GognyCSE nucl-th/0701037
• Isovector effective mass PRC 74 044315 (2006)
• Demonstration that the tensor force explicitly
  impacts shell structure at large isospins PRL
  95, 232502 (2005)
• Low-energy strength in exotic nuclei within
  DFTQRPA (pygmy and exotic modes) PRC 74, 044301
  (2006) PRC 73, 024312 (2006)
• Towards microscopic theory of LACM
• Projected HFBGCM description of coexistence
  phenomena PRC 69, 064303 (2004)
• Fission theory 5D micro-macro barriers PRL 92,
  072501 (2004) HFBTDSE PRC 71, 024316 (2005)
• Time-dependent approaches to nuclear fusion 3D
  TDHF PRC 73, 054607 (2006) TDSE PLB 637, 53
  (2006)
• Algebraic description of phase transitions
  critical point symmetries PRL 91, 132502 (2003)
• Multistep reactions theory using coupled
  discretized continuum channels PRC 65, 024606
  (2002)
• Determination of spectroscopic factors using ANC
  PRC 72, 017602 (2005)
• Isospin dependence of real and imaginary
  potentials PRL 97, 162503 (2006)

10
Impact within and outside of the field A. Within
Hard evidence of the impact!

• Physics of nuclei (guiding experimental programs,
  see talks by Casten, Macchiavelli, Glasmacher, de
  Jager)
• Can a bound tetraneutron exist? PRL 90, 252501
  (2003)
• Analysis of parity-violating electron scattering
  and proton neutral weak axial form factor PRL
  92, 102003 (2004)
• NCSM demonstration of importance of NNN forces in
  spectroscopy PRC 68, 034305 (2003)
• Nuclear level densities (high-T AFMC shell
  model) PRC 68, 044322 (2003)
• Shell structure of neutron-rich nuclei PRC 71,
  041302 (2005) Phys.Rev. C 66, 054313 (2002)
• Predictions of nuclear chiral rotations Phys.
  Scr. T125, 1 (2006) PRC 73, 054308 (2006)
• Structure of the heaviest and superheavy nuclei
  Nature, 433, 705 (2005) PRC 67, 024309 (2003)
• Astrophysics (see talks by Truran, Lattimer,
  Wiescher, Blackmon)
• Radiative and weak capture reactions at very low
  energies (GFMC) NPA 777, 111 (2006)
• Superscaling and high-energy ?-nucleus
  scattering PRC73, 035503 (2006) PRL 95, 252502
  (2005)
• Implementing nuclear physics in supernova models
  (SM, RPA) PRL 91, 201102 (2003)
• Studies of nuclear fusion in dense matter
  astrophysics PRC 72, 025806 (2005)
• Neutron stars
• Neutron star crust structure (DFT) NPA 719, 217c
  (2003)
• Neutron stars, EOS and neutron skin Ap. J. 593,
  463 (2003)
• Pairing, phase transitions and cooling PRL 92,
  082501 (2004) RMP 75, 607 (2003)
• Nucleosynthesis (SM, DFT) NPA 752, 560 (2005)

11
Impact within and outside of the field B.
intersections

• Dilute Fermions with large/infinite scattering
  length impact in nuclear, cold-atom physics,
  condensed matter and astrophysics (neutron star
  crust, cooling) PRL 91, 050401 (2003) 172
  citations
• EOS, pairing gap near unitarity predicted at T0
  and T0 PRL 96, 090404 (2006) 43 citations
• DFT description PRA 74, 041602(R) (2006)
• EFT/RG treatment of cold atoms cond-mat/0606069
• Pairing in asymmetric Fermi gasses PRL 97,
  020402 (2006)
• Coupled cluster theory, method of moments impact
  in nuclear physics and quantum chemistry PRL 92,
  132501 (2004)
• DMRG approach to nuclei and open quantum systems
  Rep. Prog. Phys. 67, 513 (2004)
• Description of weakly-bound and unbound states of
  many-Fermion systems PRL 97, 110603 (2006)
• Shell model with random interactions quantum
  chaos,quantum dots PRL 93, 132503 (2004) PRB
  72, 045318 (2005) PRB 74, 165333 (2006)
• Quantum phase transitions in mesoscopic systems
  impact in nuclear, cold-atom, molecular physics
  PRL 92, 212501 (2004) NPA 757, 360 (2005)
• Applications of SM and DFT to atomic physics
  PRA66, 062505 (2002)
• Pairing correlations in ultra-small metallic
  grains (studies of the static-to-dynamic
  crossover) RMP 76, 643 (2004)

12
Identify the major accomplishments in your area
since the last long range plan II. Community
The RIA Theory Group (RIATG)
Thank you RIA!!!!!
13
Early 2003 Idea behind RIATG conceived November
2003 First RIATG meeting, Tucson November 2003
NSAC Theory Report March 2004 RIATG Charter
approved October 2004 Second RIATG meeting,
Chicago September 2005 Blue Book
finalized September 2005 Third RIATG meeting,
Detroit July 2006 JUSTIPEN launched Nov 2006
UNDEF SciDAC-2 funded (DOE and NNSA) Dec 2006
INCITE award (DOE/SC 5M processor hours)
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Accomplishments summary

• Progress in all areas
• Splendid prospects
• Great Expectations

see below
15
Identify the most compelling scientific questions
and opportunities for the next decade (within US)
and their scientific impact

• Working on a bridge between hadrons and nuclei
  (e.g., lattice QCD with smaller pion masses
  match ?PT with lattice results)
• Developing a stringent framework for in-medium
  modifications
• Realistic Hamiltonian (3-nucleon interaction)
  describing matter and nuclei
• GFMC for (i) stable excited states in 12C, A11
  nuclei, unnatural-parity states in A9,10 and
  states outside p-shell such as second 0 in 12C
  (ii) scattering states in He and Li nuclei
• Studies electroweak observables, including low
  energy radiative captures, form factors, weak
  transitions, etc., with the aim of constructing a
  "realistic" nuclear electroweak current
• Studies of correlations via (e,e'p) and (e,e'pN)
  reactions
• Removing model from shell model Applications
  of NCSM with NNNNN(NNNN) chiral EFT forces to
  light nuclei (structure, reactions/RGM/GSM) help
  in determining NNN LECs NCSM in a symplectic
  basis
• Bridging light and heavy applications of CC
  theory with NN and NNN forces to halos, unbound
  states, and A40-100
• Bridging structure and reactions advanced GSM,
  CSM calculations for complex open nuclei,
  including halo systems development of realistic
  interactions.

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Opportunities (cont.)

• Development of realistic nuclear energy density
  functional (rms error on masses
• Microscopic foundations of NDFT (EFTRG, SM,
  ab-initio)
• Understanding of density dependence, time-odd
  fields, effective mass, correlations
• Firm analysis of uncertainties
• Applications of modern adiabatic and
  time-dependent theories of LACM to coexistence,
  fusion, fission tests of non-adiabatic
  approaches
• Bridging micro and macro microscopic foundation
  of symmetry-dictated approaches (predictability
  added!)
• EOS fully characterized at low to moderate
  densities
• Superfluid gaps in nuclear matter pinned down
  with calculations tied to experimental results in
  cold atoms and elsewhere Pairing in asymmetric
  systems (neutron-proton pairing, polarized cold
  atoms, and exotic states in nuclei)
• Isospin dependence of low- and high-frequency
  multipole/spin-isospin strength (E1 and GT in
  particular)
• Convergent treatment of many-body continuum
• Theoretical justification of surrogate reactions,
  such as (d,p)
• Quantum multi-step excitations in nucleon-nucleus
  collisions
• Microscopic optical potentials and level
  densities
• Time-dependent investigations of the role of
  neutron skins for heavy ion fusion

17
What will be the scientific impact on other
fields, are there interdisciplinary aspects?

• Studies of superfluidity in strongly-correlated
  systems at various density regimes (nuclei, cold
  atoms, grains, quarks)
• AFMC determinations of the level density
  (tackling the fermionic sign problem)
• Applications of nuclear structure models
  (ab-initio, SM, DFT) to astrophysics (EOS,
  masses, reaction and decay rates, electroweak
  capture rates, neutrino propagation in nuclear
  matter)
• Applications of nuclear structure models
  (ab-initio, SM, DFT) to fundamental
  interaction/hadronic physics. It is crucial to
  have reliable estimates of electroweak matrix
  elements or contaminations from nuclear many-body
  effects (correlations, two-body currents, etc.).
• Applications of nuclear structure models to
  nanostructures
• Study random interaction effects in quantum dots
  in the presence of spin
• Develop a suitable random matrix theory to
  describe the mesoscopic fluctuations in graphene
  quantum dots and identify the relevant symmetry
  classes
• Studies of open many-body systems using GSM/CSM
  (nuclei, atoms and molecules, nanostructures,
  hadrons)
• Studies of quantum phase transitions and
  phase-transitional behavior

18
Relevance of Nuclear Theory Addressing national
needs

• Advanced Fuel Cycles
• Workshop in August 2006 identifying needs.
• neutron-reaction cross sections from eV to 10
  MeV
• the full range of (n,f), (n,n), (n,xn), (n,g)
  reactions
• heavy transuranics, rare actinides, and some
  light elements (iron, sulfur)
• Quantified nuclear theory error bars
• Cross sections input to core reactor simulations
  (via data evaluation)
• BETTER CROSS SECTIONS AFFECT both SAFETY and
  COST of AFC reactors.
• Science Based Stockpile Stewardship
• Radiochemical analysis from days of testing
  inference on device performance shows final
  products but not how they came to be.
• Typical example Yttrium charged particle out
  reaction. LES THAN 10 of cross sections in
  region measured.
• Theory with quantifiable error bars is needed.

These two examples point to the relevance of
Nuclear Theory to OTHER programs of national
interest. Quantifiable theory error bars is a key
desire. Room for large-scale computing (SciDAC)
AFC workshop proceedings www.sc.doe.gov/np/progra
m/docs/AFC_Workshop_Report_FINAL.pdf The
Stewardship Science Academic Alliance program
workshop http//www.orau.gov/2007SSAAS/index.htm
19
A "lower cost" version of an advanced Rare
Isotope facility is explicitly mentioned in the
charge as the main major new facility for our
area compatible with projected funding levels.
What role does this facility play in realizing
the major future opportunities in the area you
are covering?

• RIA-lite is crucial for theory
• The unique data
• A unifier

• From the RIATG Manifesto
• A unified and consistent approach to nuclear
  structure phenomena (general)
• Nuclei at the extremes of the nuclear chart can
  magnify important features of the nuclear
  many-body problem and principal uncertainties of
  the theoretical description (RIA specific)
• Spectroscopy of exotic systems will be an
  invaluable source of information to learn more
  about up to now poorly known channels of the
  shell-model interactions and energy density
  functionals (RIA specific)

also RIA Brochure, RISAC Report
20
What facilities and other resources are needed
for realizing these opportunities? What other
needs does your field have until the new RNB
facility is operational?
Progress since the 2002 LRP and A Vision for
Nuclear Theory (B. Mueller)

• Postdoctoral prize fellowships
• Graduate fellowship program
• Enhanced OJI awards
• Topical centers
• Centers of excellence
• Large scale computing initiatives
• Elimination of NSF/DOE disparity
• Increased use of bridge funding
• Leveraged support for sabbaticals

Under active consideration for FY07
Considered in broader context (Education Report)
Positive response
Unrequested proposals submitted to DOE under
consideration
Currently dormant
Happened
Aim in 50 growth in funding
Agency positive to bridging opportunities
Currently dormant

• Need data for calibration and testing!
• (to keep theory - and experiment - honest)
• LENP facilities and future RIA - for isospin,
  spin, and mass directions
• JLab - for connection to QCD/hadrons, high-k
  sector, in-medium,

21
DOE FY 2006 NP Workforce Survey
Results www.sc.doe.gov/production/henp/np/mnpwr/re
port2006/index.htm
DOE Nuclear Theory Support by Subfield (FY05 in
k)
5 INT
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Graduate Students, Junior Faculty

• Each milestone requires a substantial community
  of collaborating theorists, with continuing
  influx of bright young talent (? 20).
• 41 milestones (without JLab 12 GeV and RHIC
  upgrades and without RIA !) require comparable
  number of theory communities.
• 41 x 20 / 2 400 (?)

Nuclear theory effort must be substantially
strengthened and continuously revitalized
23
Instead of conclusions a proposal
Possible TM Recommendation Strongly increase
support for theoretical efforts in the areas of
nuclear structure, nuclear reactions, and nuclear
astrophysics, in concert with an overall increase
in nuclear theory as recommended in the 2003 NSAC
Theory report.