Nuclear structure and dynamics The theory activities within

Nuclear structure and dynamics (The theory activities within INFN – in brief !) Seminar at Nu. PECC Meeting LNS, March 12 th, 2010 G. Colò

What, where and who ? Milano Few-body and nuclear matter: Pisa, Trento, Padova, Catania Shell model: Napoli Mean field and beyond: Milano, Napoli, Lecce, Firenze Algebraic models: Padova Trento Padov a Torino Pisa Firenz e Lecce Napoli Reactions: Catania, Padova, Milano, Pisa Electroweak interactions: Torino, Lecce Neutron stars, astrophysics: Catania, Milano, Pisa Catani a FTE = 55 (individuals ~ 70)

• 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 Link Programme # CN/Asia-Link 008 (94791)

Key question : the NN effective force The effective force is related to a method ! QCD (χPT) Fit to observables free or bare NN interaction ab-initio approaches (variational, Montecarlo …) Shell model effective NN interaction relativistic models non-relativistic models Skyrme, Gogny

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”. 3 -body: Variational methods, Hyperspherical harmonics expansion, Fadeev equations The Trento group has proposed a method to treat the manybody problem exactly also in the continuum, namely the Lorentz Integral Transform (LIT) method. Electron RL(E, q) vs E in 4 He

Pisa : accurate calculations of scattering observables, of M 1 transitions including exchange currents, and PV components in the NN potential H. Witała et al. , PRC 73, 044004 Nd spin-transfer coefficients extracted from elastic data at 22. 7 Me. V Chiral potentials: blue=NLO, red=NNLO including 3 -body Going to next order: sometimes better and sometimes worse ? ?

Napoli : shell-model studies of exotic nuclei Use of modern Vlow-k Intensive exploration of the region around 132 Sn. L. Coraggio et al. , PRC 80, 044320. 3 -body force ?

Energy density functional (EDF) methods 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 • Linear response theory can be applied → self-consistent description of nuclear collective motion Milano: accurate calibration of the functional using exp. data for the collective response Coll. with LNS: functionals derived from Brückner-HF

The largest uncertainities concern the ISOVECTOR, or SYMMETRY part of the energy functional which is very POORLY constrained. usual (stable) nuclei neutron-rich (unstable) nuclei Dipole response PDR GDR 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

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 Vlasov Boltzmann Langevin Courtes y: B. Tsang Analysis of the isospin content of the fragments, or of other observables (cf. double rations) ↔ Symmetry energy Vlasov Boltzmann Langevin

Nuclear and Coulomb inelastic excitations Microscopic double folding Role of nuclear and Coulomb potentials in the excitation of PDR and GDR Matching of structure and reaction theories Courtesy: E. Lanza 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

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

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. nucleon } incl. hyperons 　　 P. Finelli et al. H. -J. Schulze et al, PRC 73 (2006) 058801 • 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.

A bottom line… • The interest of 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).

New requests for computing 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 CSN 4 -INFN for new local units: • 6 - or 8 -core • 32 GB RAM • 2 TB HD (6 units).