This is the final talk of NSTAR2011 conference. It is not a summary talk, but rather a looking forward to what still needs to be done in excited baryon physics. In particular, we need to hone our tools connecting experimental inputs with QCD. At present we rely on models that often have doubtful connections with the underlying theory, and this needs to be dramatically improved, if we are to reach definitive conclusions about the relevant degrees of freedom of excited baryons. Conclusions that we want to have by NSTAR2021.
The conference NSTAR 2000 was part of a series of conferences and workshops that began in New York in 1988. Since then, the field of excited nucleons and hadron structure has developed enormously, and the scope has broadened. Most significantly, new experimental facilities have come into operation, allowing precise measurements of resonance couplings and transition form factors. The search for ?missing? quark model states and gluonic excitations in complex hadronic channels is now possible.On the theory side, new and promising developments have emerged: quark models with meson degrees of freedom, hybrid baryon models, and studies of baryons in the limit of many colors. For the first time, lattice QCD has been employed to calculate masses of excited nucleons. Nucleon resonances are now recognized as providing significant contributions to the nucleon spin sum rules, as well as the Gerasimov-Drell-Hearn and Bjorken integrals, at finite momentum transfer.
This book is devoted to the investigation of the strongly interacting hadrons — to a quark model operating with effective color particles, constituent quarks, massive effective gluons and diquarks. The study of strong interactions based on effective constituent particles requires a solid ground of experimental data, which we now have at our disposal with the serious progress made in the investigation of hadrons, especially meson states.The present understanding of QCD applied to strong interactions can be distorted by prejudices. Therefore, the way followed by the quark model is to rely on the experiment and to restore the effective Hamiltonian on the basis of QCD on the one hand, and, on the other, of the spectral integral method.Baryon-baryon and antibaryon-baryon interactions are studied with the purpose of unambiguous applications of the written formulae to the interpretation of experimental data — to the observation of new meson and baryon resonances. The technique used is the spin-orbital momentum expansion of the amplitude. This method is our basic approach to the proper treatment of experimental data. The photon-induced reactions are also considered and the problem of form factors is discussed.
This volume discusses the exciting physics with new accelerator facilities, which are being constructed or proposed in various places. The facilities are RHIC (Brookhaven), CEBAF (TJINP), SPring-8 (Nishi-Harima), RIBF (RIKEN), JHP (KEK-INS), RIB (MSU), LISS (IUCF) and COSY (Juelich). RHIC aims at the creation of a QCD deconfinement phase and the study of the properties of such matter. CEBAF and SPring-8 use leptons to probe the quark-gluon structures of hadrons and nuclei. LISS and COSY use high resolution hadron beams to study hadron structures. JHP produces strong secondary hadron beams for hyper-nuclear physics and rare decay studies of basic symmetries. RIBF and RIB produce radioactive nuclear beams for the study of the nuclear structure of unstable nuclei far from beta stability, and astrophysics issues.
This volume brings together experts on the quark-gluon structure of matter as it applies to nucleon resonance physics. The contributions discuss the latest findings in areas such as meson production via electromagnetic and hadronic reactions, baryon resonance structure in chiral and lattice QCD approaches, and the extraction of resonance parameters from coupled-channels analysis of data.
c Societ` a Italiana di Fisica / Springer-Verlag 2008 The 11th Workshop on The Physics of Excited Nucleons, NSTAR 2007, was held at the University of Bonn, Germany,fromSeptember5–8,2007.ItwasthelatestofaseriesofsuccessfulconferencesattheRensselaerPolytechnic Institute (1988), Florida State University (1994 and 2005), Je?erson Lab (1995 and 2000), INT Seattle (1996), GWU ? Washington (1997), ECT Trento (1998), Mainz (2001), Pittsburgh (2002) and the LPSC Grenoble (2004). A Baryon Resonance Analysis Group (BRAG) meeting immediately before the workshop focused especially on the physical meaning of bare and dressed scattering matrix singularities. A focus workshop on? photoproduction rounded o? the NSTAR 2007. The goal of NSTAR 2007 was to bring together experts on all areas of physics relevant to baryon spectroscopy, both in experiment and theory. Latest results were presented in 30 plenary talks and 34 parallel contributions, the proceedings of which are collected in this volume. The workshop was attended by 123 scientists of 41 universities and laboratories from 16 countries. Exciting new high-precision data were shown from facilities in Asia, the US and Europe, e.g. BES, BNL, COSY, ELSA, GRAAL, JLab, MAMI and LEPS. Large-acceptance detectors provide complete angular distributions in many reaction channels. Particular emphasis is put on the measurement of single and double polarisation observables such that many new polarization measurements can be expected in forthcoming meetings.
The generalization of QCD from three to NC colors, developed in 1974 by Nobel laureate Gerard 't Hooft, has proved to be an extraordinarily useful and robust theoretical extension for studying the behavior of strong interaction physics. This book is the proceedings of the first-ever meeting exclusively devoted to large NC QCD. The workshop brought together representatives of many subdisciplines for a “meeting of minds” on topics ranging from finite temperature and density to the lattice, perturbative QCD, instantons, mesons, baryons, and nuclear physics. Beginning with 't Hooft's keynote presentation, the contributions are designed to introduce uses of large NC methods in each specialty to a broader particle physics audience.
