Discussion on Low-energy nuclear structure and reactions

Report
Discussion on Low-energy nuclear structure and reactions
Workshop on Future directions in the physics of nuclei at low energies
May 21st-23rd 2014, ECT*, Trento, Italy
Discussion
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Topics to be discussed
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Organization/strategy of the field in Europe
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Physics (theory and experiment)
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Any other you feel strong about
Points to jumpstart the discussion
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Key points raised by the 3 theory + 2 experimental speakers (have them as back-up slides here)
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Points to be raised by conveners in this brief intro
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Any point you wish to raise
Objectives
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Come up with a list of important points for the future (to be further elaborated and discussed)
Rule of thumb: If we take 20mns per topic we can cover about 11 of them…
General perspectives from theoretical viewpoint
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Justification/interest/visibility/organization of the field
II. General goals of nuclear structure and reaction theory
III. Going towards very neutron-rich nuclei (and other extremes)
IV. Scale- and scheme-dependence of analysis and interpretations
V. Take true advantage of massively parallel computing
General perspectives
I.
Justification/interest/visibility/organization of the field
1)
Justification and visibility need healthy balance
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First and foremost for, and by, the field itself: always (re)phrase key questions
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Interdisciplinary features further strengthen the field: new ideas?
2)
Add “new” degree of freedom to our system, e.g. should it be the strangeness/hyper-nuclei era?
3)
New thinking come from extremes BUT true understanding come from systematics
4)
Never trust experiment/theory without uncertainty quantification
General perspectives
II. General goals of nuclear structure and reaction theory
1)
What do we want to achieve with QCD-based approaches?
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From few- to many-body physics with controlled approximations from consistent ANF
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Emergence of magic numbers, collective and individual excitations at the same energy scale?
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Limits of nuclear stability as a function of I, A, J, E, T, S?
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Phenomena: superfluidity, exotic collective excitations, one-nucleon dynamics, halos…
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Precise/systematic/controlled account of rich phenomenology at play in stable and unstable systems
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Uncertainty quantification and error propagation
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Unified view of structure and reactions
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…
General perspectives
III. Going towards very neutron-rich nuclei (and other extremes)
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Is there any innovative production mechanism on the table?
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Predictive theories with as large a reach as possible
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E.g. innovative ab-initio many-body methods + ab-initio-rooted EDF and CI
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Era of theoretical uncertainty evaluation (not easy)
General perspectives
IV. Scale- and scheme-dependence of analysis and interpretations
1)
2)
Always split true observables from scale-dependent interpretation-related ingredients
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E.g. wf, correlations, ANF component, spectroscopic factors, s.p. shell structure…
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Needs to be fully integrated in our “mental algorithm”
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Needs to be seriously communicated in theoretical modeling and “extraction”
Reaction theory needed to revisit various factorization schemes as a function of scale
General perspectives
V. Take true advantage of massively parallel computing
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Arena for collaboration between nuclear theorists, applied mathematicians, computer scientists
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How to promote? E.g. SciDAC-DOE in the US
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What is feasible within the next five years? Fifteen years?
Points from Elias
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Wishes from theory
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Converging mass predictions for exotic nuclei
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Deep understanding of clusterisation in nuclei
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Unification of structure and reaction: accurate reaction models based on TD-EDF
4)
Determination of EoS quantities: L, Ksym, Kinf
II.
Wishes from experiment
1)
Measurement of soft and exotic modes in exotic (deformed) nuclei
2)
Neutron skin (direct measurement)
3)
GMR in extended isotopic chains including exotic nuclei
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Clusterisation signals in the ground state of light nuclei ?
Points from Jacek
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Need for theoretical uncertainty estimate and propagation
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The family of Skyrme EDF parametrizations reflect large intrinsic error bars
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Fitting procedure strongly impact performance
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Need to quantify and propagate (statistical) uncertainties in fit
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Improve on performance of current EDF parametrizations
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One should be impressed by performance achieved by current EDF calculations
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However current, i.e. Skyrme, Gogny, relativisitic families of EDF parameterizations are insufficient
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Need to change paradigm to reach spectroscopic quality
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New analytical form(s) with enriched physics based on a systematic approach
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More professional fitting strategies including uncertainty evaluation and propagation
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Both points must benefit from emerging ab-initio many-body theories
Points from Javier
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Wishes from theory
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Precise and extensive enough ab-initio calculations of light- and medium-mass nuclei to test ANF
 NCSM, SCGF, CC, IMSRG
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Calculations based on c-EFT ANF that cover the nuclear chart
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CI, EDF
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Uncertainties associated with input ANF and many-body method must be systematically assessed
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Exploit high-performance computing
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Improved ANF based on c-EFT (and lattice-QCD?)
II.
Wishes from experiment
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Push towards the neutron drip-line and beyond, e.g. light unbound nuclei

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