Present Status of the Nuclear Interaction Theory

Date :From 2014-08-25 To 2014-09-19
Advisory committee :M. Baldo (INFN,Catania, Italy), T. T. S. Kuo (Stony Brook Uni.,USA), Z.Y. Ma (CIAE, Beijing, China), J. Meng (Beijing Uni.,China ), R. Machleidt (Idaho Uni., Moscow, USA), Z.Z. Ren (Nanjing Uni.,China), P. Ring (Technical Uni., Munich, Germany), A. Schwenk (Technische Uni.,Darmstadt,Germany), Z.Y. Zhang (IHEP -CAS, Beijing, China), E.G. Zhao (ITP-CAS, Beijing, China)
Local coordinators :B.S. Zou (ITP-CAS, Beijing), S. G. Zhou (ITP-CAS, Beijing,co-chair), W. Zuo (IMP-CAS, Lanzhou, co-chair), Li-Sheng Geng (Beihang Uni., Beijing)
International coordinators :D. Blaschke (Wroclaw Uni., Poland), V. Greco (Catania Uni&LNS-INFN, Italy), U. Lombardo (Catania Uni&LNS-INFN, Italy, co-chair), U. Meissner (Bonn Uni., Germany, co-chair), H. Sagawa (Aizu Uni., Japan), H.J. Schulze (INFN,Catania, Italy)


One of the most important frontiers in nuclear Science is to understand the nature and microscopic origin of nuclear (NN) force which binds nucleons into nuclear many-body systems.  In the last decades the laboratory of the nuclear force has been enriched  with exotic nuclei, high energy heavy-ion (HI) collisions and astrophysical compact objects. Furthermore, these investigations have been extended to the forces between baryons, in particular hyperon-nucleon (YN) and hyperon-hyperon (YY) interactions. New theoretical approaches and methodologies have been developed  in order  to go beyond the traditional models of the baryon-baryon interaction and to work out its connection to the underlying theory of the strong force, Quantum Chromodynamics (QCD).  Therefore, it is timely to bring together scholars of different expertise and give them enough time for wide and detailed debates, emphasizing  research collaborations and training-through-research of the postdocs and advanced graduate students joining the workshop . The latter  is in fact one main tasks of the programs of the KITPC/ITP-CAS Institute.
 In our approach  such a meeting will proceed starting with the discussion of the one-boson exchange (OBE) models of the nuclear force along with the more recent effective field theories (EFTs), emphasizing their progress in formulating predictions in the present nuclear phenomenology and astrophysical observations.  Modern versions of the OBE model are able to reproduce with great accuracy the two-body phase shifts up to the inelastic threshold, but, in addition to two-body forces (2BF), three-body forces (3BF) are demanded by nuclear spectra, few nucleon systems and definitely  by heavy-ion collisions and astrophysical observations. In such a context TBF have been introduced following either phenomenological  or  microscopic approaches using the same meson parameters as in the realistic OBE  forces.
On the other hand, EFTs for the nuclear force have been initialized by Steven Weinberg and have led to a new understanding of the underlying two-, three- and four-nucleon interactions and their coupling to pions and external probes. This allows in particular to address fundamental symmetry tests in nuclei, such as isospin, parity and CP violation. Going to a more microscopic level, some room should be given  to ab initio QCD calculations of NN, NY and YY interactions, to hadron-to-quark phase transitions and to the constraints coming from the neutron-star structure. The inclusion of the strange quark open new lines of research in nuclear physics and is actively pursued at running and upcoming facilities.
Reliable non-perturbative many-body methods have been devised to convert any model of hadron interaction into  models of effective interaction, with 2BF and the  3BF (or more) components.  A particular new class of effective forces are based on renormalization group methods, like Vlow-k , or the similarity renormalization group. This is one of the most important developments to get a handle on the nuclear many-body problem. Considerable space should be devoted to the effective interactions: how are they linked to the fundamental few-nucleon forces, how do they embody the strong correlations in nuclei and nuclear matter and how do the hadron excitations affect the NN interaction in dense matter. Phenomenological forces, based on empirical nuclear data, and energy density functionals, built up from ab initio calculations, should be matched up or against in the description of the  experimental data in the terrestrial labs and astronomical observations in space labs. Furthermore,  specific properties of the nuclear force, such as tensor contribution and pairing coupling, should be elucidated. Another important topic is the development of novel methods to tackle the nuclear many-body problem based on high-performance computers, allowing for ab initio  calculations and embedding   the new nuclear force models into more conventional many-body approaches.

The aim of this program is: (i) to strengthen the collaboration of researchers working on different aspects of the NN interaction. (ii) to promote new research projects between Chinese scientists and their overseas colleagues  (iii) to attract and provide an initial training in nuclear physics and astrophysics for the most talented young Chinese scientists, fostering future scientific exchange between Chinese and foreign Institutes. For achieving these goals, a number of afternoon sessions will be devoted to lecture series and  discussion/collaboration meetings, some of which focused on technical aspects, including available computer codes and their use.

Preliminary Program

Realistic Interactions (August 25 – September 3)
Conveners: U. Meißner, W. Zuo
Key topics:
Realistic NN interaction:  from meson-exchange model  to chiral expansion
Few-nucleon interaction from chiral perturbation theory
Hadron excitations and nuclear interaction
Isospin violation, quark masses and symmetry tests
NY and YY force from lattice QCD
Hyper-nuclei and strange nuclear matter
Specific contributions
NN interaction  and light nuclei from lattice QCD
2BF and 3BF from meson-exchange model: EoS of  nuclear matter
Few body systems and need of 3BF
Strange matter and quark condensation in neutron stars

In-medium  Nuclear Interaction  (September 4 – September  11)

Conveners:  U. Lombardo, K. Hebeler

Key topics:
Renormalization of the NN interaction and low momentum potential 
Brueckner  and Dirac-Brueckner  theory of nuclear matter
Self-consistent Green’s function method for nuclei and nuclear matter
Variational-based many body approaches 
Many-body forces from chiral expansion
In-medium renormalization of the NN Interaction and in-medium many-body forces
Monte Carlo approaches to nuclear physics
Nuclear lattice simulations with chiral EFT

Specific  contributions

Effective lagrangian approaches
Renormalization group methods: application to nuclear matter
Constraints on the EoS from neutron-star structure
Pairing from MC calculations and many-body approaches

Effective Nuclear Interaction (September 12– September  19)

 Conveners: H. Sagawa, S.G. Zhou

Key topics:

Overview of the energy density functionals 
Skyrme-like forces for the nuclear and nuclear matter structure
Relativistic mean field models
Nuclear physics in compact astrophysical objects
EoS of nuclear matter and heavy-ion collisions
Origin and probes of the tensor force 

Specific contributions.

Nuclear structure with Skyrme forces beyond the mean field  approximation
BCS theory and beyond:  new pairing states
Evidence of pairing states in  neutron stars
Joining nuclear physics and perturbative QCD

Afternoon Sessions

Lecturing sessions (two per week, three hours each )
Non relativistic many-body theory of nuclear systems
Renormalization group method
Introduction to chiral EFT for nuclear forces
Chiral dynamics in nuclei and nuclear matter
Introduction to nuclear lattice simulations
Limits of the nuclear landscape
Superfluidity in nuclei and neutron stars
The nuclear EoS:  from HIC to neutron stars
Round tables and Discussion/Collaboration Meetings (to be scheduled) 

Confirmed  international participants
S. Aoki  (Tsukuba Uni.,Japan),
M. Baldo (INFN,Catania,Italy),  Int. Adv. Board and key participant
D. Blaschke  (Uni. Wroclawski, Poland), ICC and key participant
N. Chamel (Uni. Libre de Bruxelles, Belgium), key participant
G.L. Colò (Milano Uni.,Italy),
E. Epelbaum (Julich Uni.,Germany), key participant
C. Fisher (Giessen Uni.Germany) , 
V. Greco( Catania Uni&LNS-INFN, Italy), ICC and key participant
T. Hatsuda (Riken Lab., Japan),
 K. Hebeler (Ohio State Uni.,USA),
E. Hiyama (KEK, Tsukuba,Japan), key participant
N. Kaiser (TU Munich, Germany), key participant
A. Kievsky (INFN, Pisa, Italy),
T.T.S. Kuo (Stony Brook Uni., USA),
Dean Lee (North Carolina Uni.,USA) ,
U . Lombardo ( Catania Uni.&LNS-INFN, Italy), co-chair
R. Machleidt (Idaho Uni., Moscow, USA), Int. Adv. Board and key participant
U. Meißner (Bonn Uni., Germany), co-chair
W. Nazarewicz (Uni. Tennessee, USA), key participant
Dany Page (UNAM, Mexico), key participant
A. Polls (Barcelona Uni.,Spain)
H . Sagawa (Aizu Uni.,Japan),  ICC and key participant
B.J. Schaefer (Graz Uni., Austria),
H.J. Schulze (INFN,Catania, Italy), ICC and key participant
A. Schwenk (Technische Uni.,Darmstadt, Germany)