Les jeunots en physique nucl

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Les jeunots en physique nucléaire de basse
énergie Some remarks on current theoretical
activities France vs the rest of the
world Thomas Duguet (SPhN)
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Theory of Nuclei

• Goals
• Comprehensive and unified description of all
  nuclei
• Low-energy reaction and structure properties
• From basic interactions between protons and
  neutrons
• Understand different states of nuclear matter in
  astrophysics environments
• Difficulties
• Self-bound, two-component quantum many-fermions
  system
• Complicated interaction from low-energy regime of
  QCD
• Tensor and spin-orbit components
• Unnaturally large scattering lengths (2-body
  virtual and bound states)
• NNN unavoidable
• Repulsive core and strong tensor at short
  distances?
• Properties of finite and bulk nucleonic matter
• Deuteron to SHE nuclei to neutron stars and
  nuclear (strange) matter
• Need to extrapolate to unknown regions
• Some trivial facts
• No one size fits all theory for nuclei

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Selection of advances in the recent years

• Ab-initio (NCSMGFMC) methods allowed for
  interaction tests
• Consistent proof of the role of NNN interaction
  in light nuclei
• Nuclear interactions c-EFT provides missing
  links
• Explains hierarchy NN gt NNN gt NNNN 2N-3N, ?N,
  ??, consistency
• Chiral symmetry breaking of QCD encoded gt
  constrains ?N interaction
• Renormalization Group provides gentle NN
  (Vlowk) NNN
• Use relevant degrees of freedom/energy scales for
  low energy nuclear physics
• Many-body problem becomes (mostly) perturbative
  (HUGE practical implications)
• Quantitative microscopic nuclear structure
• CI calculations into the fp shell sSD608 140
  keV!
• LACM shape coexistence and fission
• Transfermiums as a window on SHE nuclei
• First EDF mass tables (SR) and systematics of
  correlations (MR) in heavy nuclei
• Multipole strength S(El)/b-decay from fully
  self-consistent (deformed!) QRPA
• Shell evolution towards drip-lines role of
  tensor force raised
• Integration of structure and reaction for light
  nuclei
• Multistep reactions calculations using coupled
  discretized continuum channels
• GSM, CSM and SMEC to incorporate (many-body)
  continuum in CI
• Use of nuclear inputs into reaction models e.g.
  JLM optical model

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Selection of challenges for the coming years

• Bridge between hadrons and nuclei
• e.g., lattice QCD with smaller pion masses match
  ?PT with lattice results
• NNN interaction
• Test NNN (NNNN) from c-EFT at N3LO through NCSM
  calculations of light nuclei
• Role in medium mass nuclei through CC and
  spectroscopy through CI and EDF
• Interplay of phenomenological and non-empirical
  EDF
• Constructed from low-momentum interactions/c-EFT
  and benchmarked against CC
• Predictability (theoretical error bars) and
  accuracy (new (re)fitting protocols)
• Strong focus on spectroscopy
• Coherent formulation of SR and MR EDF methods
  from first principle
• Superfluidity
• Nature of pairing correlations in finite nuclei
• Pairing in asymmetric systems e.g.
  neutron-proton pairing, polarized cold atoms
• Shell position/evolution in stable/neutron rich
  nuclei
• Role of tensor, NNN, spin-orbit (matter
  diffusivity), other?
• LACM coexistence, fusion and fission
• Quantitative methods including both diabatic and
  adiabatic effects
• Integration of structure and reaction
• Advance GSM/CCSD (interaction) and apply to
  complex open light nuclei

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Some useful experimental data (not exhaustive!!)

• Fission
• Barriers and life-time
• Mass and kinetic energy distributions of
  fragments
• Evaporated neutrons and gs
• Systematic data into the next major shell (few
  mass units)
• Mass differences e.g. shell evolution and
  pairing
• First 2, B(E2) and Qs e.g. deformation and
  shell evolution
• Single-particle energies and spectroscopic
  factors i.e. shell evolution
• Pair transfer e.g. quantitative information on
  pairing?
• Data at large deformations (low and high J)
• Beta-decay and charge-exchange reactions e.g.
  pin down theories for weak rates
• Transfermiums
• Rotational bands i.e. pairing and shell
  positioning
• K-isomers i.e. pairing and shell positioning
• Neutron radii
• Parity violation from e- scattering (208Pb) at
  JLAB i.e. Rn-Rp ltgt asym(rsat)/P(rsat/2)
• Same in more (neutron-rich) nuclei might be of
  interest
• Neutron star observations
• Thermal X-ray emission for cooling

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Young  french  theorists activities by
methods/subjects
STRUCTURE Heavy / Light REACTION Heavy / Light ASTRO NS / n Symmetry Model stand. TOTAL
(TD)EDF 11,75 / - 2 / - 1,5 / - 0,25 15,5
CI 0,5 / 2 - / - - / 1 - 3,5
GSM - / 0,5 - / 0,5 - / - - 1
Opt. Pot. - / - 1 / - - / - - 1
CChannel - / - - / 1 - / - - 1
GFMC - / - - / - - / - - -
NCSM - / - - / - - / - - -
CCluster - / - - / - - / - - -
SCGF - / - - / - - / - - -
NN/NNN - / - - / - - / - - -
TOTAL 12,25 / 3 3 / 1,5 1,5 / 0,5 0,25 22
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Are we well positioned for the next 10/15 years?

• Community extremely biased towards EDF methods
• Chance to propose a coherent effort
• Promising future as experimental facilities move
  to medium-mass exotic nuclei
• Cultural advantage but US and Japan now put
  strong emphasis on EDF e.g. UNEDF
• Our expertise suggest to
• Push MREDF methods e.g. QRPA,
  GCM/Projection-like methods
• Develop further and systematize the use of
  Time-Dependent EDF methods
• Push cross-fertilization between EDF and CI
  e.g. ESNT workshop on April 7-10
• Such a bias carries the danger to miss the big
  picture
• E.g., somewhat true about ab-initio methods and
  nuclear interactions in the 80/90s
• Could be detrimental as overlap/benchmarks are
  envisioned e.g. with CC
• Might need to recruit a few theorists with
  different expertise
• Interplay between structure and reaction e.g.
  GSM
• Hard core reaction theory e.g. issue with
  extracting spectroscopic factors
• Promising ab-initio method for medium mass
  nuclei Coupled Cluster

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Geography

• Strong on-going theoretical collaborations
• GANIL-IPNO
• CENBG-GANIL-IPNL-SPhN
• GANIL-SPhN
• Future
• Projects will naturally follow historical
  collaborations
• But new ones will hopefully arise