International Journal of Modern Physics E

A brief survey of results of studies of nuclear chirality in the mass 80 and 190 region at iThemba LABS is given, before looking at the case of ¹⁰⁶Ag in detail. Here, the crossing of a pair of candidate chiral bands is re-interpreted as the crossing of a prolate band by an aligned four-quasiparticle band.

We discuss how to use Morgan's pole counting rule to distinguish a molecular state from an 'elementary' particle. As two examples we focus on X(3872) and f₀(980) particles. A molecule may be generated from a meson loop bubble chain, and an 'elementary' particle is related to an explicit interaction field in the effective lagrangian and propagates with a Breit–Wigner propagator. For X(3872) it is found that the data favor the 'elementary' particle explanation. For f₀(980) the study becomes much more difficult, since highly nonperturbative dynamics is involved. A unitarization model analysis suggests that f₀(980)'s property is quite exotic. Unlike other light scalars, it does not behave like a state, and could be interpreted as a molecule.

Recent experimental observations of many unconventional hadronic states stimulate an interest in the structure of hadrons. While various internal configurations have been proposed, it is a subtle problem to identify the structure of hadron resonances in a model independent manner. Here we discuss the composite/elementary nature of hadrons using the field renormalization constant Z. In particular, we show that the magnitude of the effective range parameter r_e is related to the structure of s-wave near-threshold resonances.

Comprehensive understanding of the structure and reactions of light nuclei poses theoretical and computational challenges. Still, a number of ab initio approaches have been developed to calculate the properties of atomic nuclei using fundamental interactions among nucleons. Among them, we work with the ab initio no core full configuration (NCFC) method and ab initio no core Gamow Shell Model (GSM). We first review these approaches and present some recent results.

I discuss the fine-tuning of the nuclear forces and in the formation of nuclei in the production of the elements in the Big Bang and in stars.

Recent studies of (hyperonic) nuclear forces based on lattice QCD are presented. An energy independent nonlocal potential can be obtained from Nambu–Bethe–Salpeter wave function which is measured from the lattice QCD calculation with a set of interpolating fields of baryons, where a time-dependent Schrödinger equation in imaginary time is employed so as to avoid the exact ground state saturation in the numerical computation. The central and the tensor potentials of ΛN and ΣN with isospin I = 2/3 channels are presented as specific numerical examples. We also present an attempt to study the four-nucleon bound state problem using the lattice nuclear potential with stochastic variational method.

Heavy quarks play special roles in the hadron spectroscopy. Some distinct features of heavy quark dynamics and their significance in the P-wave baryons with a single heavy quark are discussed. We also explore a new color configuration in exotic tetra-quark mesons with two heavy quarks. Finally, possibility of bound states of a charmed baryon with a nucleon and nuclei are examined.

In this talk I report on the recent developments in the subject of dynamically generated resonances. In particular I discuss the γp → K⁰Σ⁺ and γn → K⁰Σ⁰ reactions, with a peculiar behavior around the K^*0Λ threshold, due to a 1/2^- resonance around 2035 MeV. Similarly, I discuss a BES experiment, decay, which provides evidence for a new h₁ resonance around 1830 MeV that was predicted from the vector–vector interaction. A short discussion is then made about recent advances in the charm and beauty sectors.

I will briefly review in this talk the most significant developments in light scalars spectroscopy that have occurred since the last edition of this Conference, although I will comment on the updates of the mass and width of different light scalar mesons in the latest edition of the Particle Data Tables, I will be mostly focusing on the major revision of the f₀(500) meson, also known as σ meson. I will explain how this major update has been driven both by new data and rigorous dispersive analysis.

Recent work unambiguously resolves the level of charge symmetry violation in moments of parton distributions using (2 + 1)-flavor lattice QCD. We introduce the methods used for that analysis by applying them to determine the strong contribution to the proton–neutron mass difference. We also summarize related work which reveals that the fraction of baryon spin which is carried by the quarks is in fact structure-dependent rather than universal across the baryon octet.