Nuclear structure and dynamics(The theory activities within INFN – in brief !)

G. Colò

Seminar at NuPECC Meeting

LNS, March 12th, 2010

What, where and who ?

Few-body and nuclear matter: Pisa, Trento, Padova, Catania

Shell model: Napoli

Mean field and beyond: Milano, Napoli, Lecce, Firenze

Algebraic models: Padova

Reactions: Catania, Padova, Milano, Pisa

Electroweak interactions: Torino, Lecce

Neutron stars, astrophysics: Catania, Milano, Pisa

FTE = 55 (individuals ~ 70)

Catania

LecceNapoli

FirenzePisa

Padova

TrentoMilano

Torino

• Collaborations with many Universities and research institutes spread around the world

• Strong link with experimental activities (proposals, joint papers, PAC participation) in Italy, Europe, USA, Japan …

• Activity oriented towards training of young scientists

One example: Asia LinkProgramme # CN/Asia-Link 008 (94791)

QCD (χPT)

relativistic models non-relativistic models

Skyrme, Gogny

free or bare NN interaction

effective NN interaction

Fit to observables

ab-initio approaches (variational, Montecarlo …)

Shell model

Key question : the NN effective force

The effective force is related to a method !

free or bare NN interaction

Tests of the bare NN interaction in bound or scattering states of few nucleon systems are performed in Pisa, Trento and Padova.

The modern few-body techniques are either “exact” or “close to”.

The Trento group has proposed a method to treat the many-body problem exactly also in the continuum, namely the Lorentz Integral Transform (LIT) method.

3-body: Variational methods, Hyperspherical harmonics expansion, Fadeev equations

Electron RL(E,q) vs E in 4He

Nd spin-transfer coefficients extracted from elastic data at 22.7 MeV

Chiral potentials: blue=NLO, red=NNLO including 3-body

H. Witała et al., PRC 73, 044004

Going to next order: sometimes better and sometimes worse ??

Pisa : accurate calculations of scattering observables, of M1 transitions including exchange currents, and PV components in the NN potential

Napoli : shell-model studies of exotic nuclei

Intensive exploration of the region around 132Sn. L. Coraggio et al., PRC 80, 044320.

Use of modern Vlow-k

3-body force ?

EE effHH

Slater determinant 1-body density matrix• The unknown exact energy is set equal (ansatz !) to a much simpler expectation value on a Slater determinant. If Heff is well designed, the resulting energy can fit experiment at best

Energy density functional (EDF) methods

Milano: accurate calibration of the functional using exp. data for the collective response

• Linear response theory can be applied → self-consistent description of nuclear collective motion

Coll. with LNS: functionals derived from Brückner-HF

usual (stable) nuclei

neutron-rich (unstable) nuclei

The largest uncertainities concern the ISOVECTOR, or SYMMETRY part of the energy functional which is very POORLY constrained.

It has been shown that the GDR can constrain the symmetry energy at density around 0.1 fm-3 while the PDR can constrain the derivative of the symmetry energy.

L. Trippa et al., PRC 77, 061304(R), A. Carbone et al., PRC in press

Dipole response

PDR GDR

LNS : focus on REACTION mechanisms and constraints extracted from observables. Big expertise in transport models, applied from intermediate (≈εF) up to relativistic energies.

Time evolution of the one-body distribution function ( , , )f r p t

Boltzmann

),,()(),(),(),( tprKfKprffhprft

LangevinVlasov

Vlasov Boltzmann Langevin

Analysis of the isospin content of the fragments, or of other observables (cf. double rations) ↔ Symmetry energy

Courtesy: B. Tsang

Nuclear and Coulomb inelastic excitations

Role of nuclear and Coulomb potentials in the excitation of PDR and GDR

Matching of structure and reaction theories

Courtesy: E. Lanza

Microscopic double folding

Reactions with (very) exotic nuclei like breakup

Advanced quantum models by Pisa and Padova groups

Fusion reactions

Two-particle transfer reactions as a probe of nuclear pairing

Catania : many-body correlations, extended linear response calculations. How reliable is it the HF-RPA level ?

Padova : algebraic approach to nuclei displaying critical symmetries. Can we pick up the interesting cases without resorting to heavy numerics ?

Milano : nuclear field theory approach to properties of single-particle, collective states and pairing beyond mean-field. Relevance of coupling of particles and vibrations at highest orders.

Lecce : FHNC calculations extended to medium-heavy systems. Is the effective tensor force quenched ?

Other approaches : more emphasis on the MB technique rather than on VNN

The physics of compact stellar objects is of course interesting in itself. In the present context, we stress the opportunity to test the nuclear models in a wide range of densities and extreme isospin asymmetry.

Properties of the crust, role of the EOS to determine mass vs. radius, role of e-capture in supernova collapse, transition to deconfined phase…

Pairing properties of neutron matter are still an open question !

Other national funding

MIUR-PRIN 2008

Many-body theory of nuclear systems and implications on the physics of neutron stars

Universities involved:

Milano

Trieste

Roma

Catania

• In summary, the different groups involved in theoretical nuclear structure and nuclear reaction physics cover, with their study, a large variety of approaches and methods.

• In some cases, there is a clear contiguity/continuity with hadron physics. Just one example: role of hyperons in nuclei and neutron stars.

• In other cases, some of the sophisticated many-body techniques introduced by the nuclear theorists are applied to other systems as well: typically, molecules and clusters or trapped atomic gases.

P. Finelli et al.

nucleon

} incl. hyperons

　　

H.-J. Schulze et al, PRC73 (2006) 058801

A bottom line…

• The interest of the theory community in nuclear structure and nuclear dynamics has a longstanding tradition, and several schools have developed – with high expertise in specific techniques, as well as strong interactions with experimentalists.

• The level of the various groups is quite high, as testified by the number of publications in high-quality journals and invited talks at conferences.

• There is still significant fragmentation in the activities; however, synergies are increasing (directly or indirectly).

So far, calculations have been based on local, existing computer resources.

A few of the mentioned groups have recently made a single request to the CSN4-INFN for new local units:

• 6- or 8-core

• 32 GB RAM

• 2 TB HD

(6 units).

New requests for computing