DISCUSSION

Ground state

Excited statesUSDA/USDB

Excited statesGXPF1A

M.B. Tsang and J. Lee et al., PRL 95, 222501 (2005)

No short term NN correlations and other correlations included in SM. Why the agreement?Predictions of cross-sections Test of SM interactionsExtraction of structure information

SFEXP=SFSM

But, in the presence of all these interesting issues, remember…

Things to consider in measurements of the single-particle strength for a state

• can use single-nucleon transfer and “standard” spectroscopic factor method• can use alternative ANC method that avoids some ambiguities in parameters• can combine the two, to avoid model dependence (TexasA&M, MSU, Surrey)• use high energy removal reactions (e.g. J.A. Tostevin approach) for hole statesAlso need to consider• quenching of pure shell model spectroscopic factors for strongly bound nucleons• effect of using realistic wavefunctions for transferred nucleon, or “standard well”• breakup of deuteron (treat with R.C. Johnson approach, “Johnson-Soper” ADWA)And what do we really compare with? Clearly, the Large Basis Shell Model, but how exactly?• Using a standard parameter set and ADWA, compare (unquenched) SM values• Using realistic wavefunctions and ADWA, compare quenched values (cf knockout)

A PLAN for how to STUDY STRUCTURE• Use transfer reactions to identify strong single-particle states, measuring their spins and strengths

• Use the energies of these states to compare with theory

• Refine the theory

• Improve the extrapolation to very exotic nuclei

• Hence learn the structure of very exotic nuclei

N.B. The shell model is arguably the best theoretical approach for us to confront with our results, but it’s not the only one. The experiments are needed, no matter which theory we use.

N.B. Transfer (as opposed to knockout) allows us to study orbitals that are empty, so we don’t need quite such exotic beams.

Partial conclusion (1)

Conclusion : • Agreement between standard prescription (WS+SM) and ab-initio• Weak asymmetry dependence within the error bars

Analysis / Interpretation Conclusion Intro: Spectroscopic Factors

12/23ECT* Trento2013

SF andvalidatedradius

Ab initiooverlap(cf W-S)

a = -0.0042(28)(36) MeV-1

Partial conclusion (2)

a = +0.0004(24)(12) MeV-1

…the reduction in the SFs is due to the many-bodycorrelations arising from the coupling to the scatteringcontinuum…. [O. Jensen et al., Phys. Rev. Lett. 107 032501 (2011)]

Spec

. Fac

tor

a = -0.0039 MeV-1

between 14O points

Analysis / Interpretation Conclusion Intro: Spectroscopic Factors

13/23ECT* Trento2013

Coupled-cluster method

Knockout results

Analysis / Interpretation Conclusion Intro: Spectroscopic Factors

14/23ECT* Trento2013

3 HOURS and FIFTY MINUTESfor discussion

Please think about any issues arising from any these talks,that you would like to raise in discussion…(perhaps here in this session, perhaps over dinner/beer so we can leave!)

We will have two short presentations, so far as I am aware, then discussion…

Partial conclusion (1)

Conclusion : • Agreement between standard prescription (WS+SM) and ab-initio• Weak asymmetry dependence within the error bars

Analysis / Interpretation Conclusion Intro: Spectroscopic Factors

17/23ECT* Trento2013

SF andvalidatedradius

Ab initiooverlap(cf W-S)