Hadron and Nuclear Physics 09

The following sections are included:

• PREFACE

• CONTENTS

We reported the study of Y(2175) in J/ψ decays, the results from a partial wave analysis of and the observation of charged κ, based on 5.8×10⁷ J/ψ events collected at BESII. We also reported the precision R values at the energy points of 2.60, 3.05 and 3.65 GeV/c² and the measurement of the line shape for the cross sections of e⁺e^- → hadrons in the energy range of 3.650 - 3.872 GeV/c². The status of BESIII running, as well as the preliminary results from BESIII are also presented.

In order to understand the structure of the X(3872), we have studied the effects of the charmonium core state coupling to the and D⁺ D^-* molecule states. We determine the coupling strength so as to reproduce the observed mass of the the X(3872). The isospin symmetry breaking is introduced by the mass differences of the neutral and charged D mesons. The obtained structure of the X(3872) is about 15% of charmoniumu, 72% of the isoscalar molecule and 13% of the isovector molecule which explains observed properties of the X(3872) well.

The research of exotic nuclei containing charm and bottom flavors is an interesting subject as a possible extension of flavors in strangeness nuclei. We consider the possible existence of exotic charm and bottom nuclei with mesons. With respecting the heavy quark symmetry, we present that the one pion exchange potential with tensor coupling induces an attractive interaction between meson and nucleon. We consider the compound states of a meson and a nucleon with spin-parity J^P = 1/2^- and 3/2^- and isospin I = 0 and 1. We find only the J^P = 1/2^- and I = 0 channel induces a stable bound state, while the others do not. We further discuss the possible bound states of a meson and two nucleons, and discuss the application to nuclei with larger baryon number.

A brief overview of the study of D_s meson is presented. "New" D_s or D_s-like mesons are introduced. The spectrum of D_s mesons is studied and the mixing of D_s mesons is discussed. Interpretation of D_sJ(2632)⁺, D_s1(2700)^±, D_sJ(2860) and D_sJ(3040)⁺ is made.

Using heavy meson chiral perturbation theory, we have calculated systematically the pion (π, K, η) and heavy pseudoscalar meson S-wave scattering lengths up to in the heavy quark symmetry limit. From a lattice simulation, we estimate the unknown low-energy constants and predict all the other unmeasured scattering lengths. We found six channels are attractive, including the isoscalar DK channel. The DK interaction may help to lower the mass of the "bare" charm-strange scalar state in the quark model through the couple-channel effect.

Photoproduction of the Λ(1405) has been studied at SPring-8/LEPS in order to understand its production mechanisms and the internal structure. The ratios of Λ(1405) production to Σ⁰(1385) production were measured in two photon energy ranges: near the production threshold (1.5 < E_γ < 2.0 GeV) and far from it (2.0 < E_γ < 2.4 GeV). The observed ratio decreases in the higher photon energy region, which may suggest different production mechanisms and form factors for these hyperon resonances. In addition to production cross sections, the measurement of the KNΛ* and K*NΛ* coupling using the photon beam asymmetry of Λ(1405) production is underway. The status of the analysis will be described.

The strangeness photoproduction process has been intensively studied based on the high-quality data of the charged kaon channel, γ + p → K⁺ + Λ(Σ⁰). On the other hand, there was no reliable data for the neutral kaon channel γ+n → K⁰+Λ(Σ⁰). The theoretical investigations suffer seriously from the lack of the data. A Substantial effort has been made to measure the γ+n → K⁰ + Σ process in the decay channel, using a liquid deuterium target and a tagged photon beam (E_γ = 0.8-1.1 GeV ) in the threshold region at Laboratory of Nuclear Science (LNS), Tohoku University.

We have taken exploratory data quite successfully with use of Neutral Kaon Spectrometer (NKS) at LNS-Tohoku in 2003 and 2004. The data is compared theoretical models and it indicates a hint that the K⁰ differential cross section has a backward peak in the energy region. The second generation of the experiment, named NKS2, is designed to extend the NKS experiment by considerably upgrading the original neutral kaon spectrometer, fully replacing the spectrometer magnet, tracking detectors and all the trigger counters. The new spectrometer NKS2 has significantly larger acceptance for neutral kaons compared with NKS, particularly covering forward angles and much better invariant mass resolution. The estimated acceptance of NKS2 is three (ten) times larger for than that of NKS. The spectrometer is newly constructed and installed at LNS, Tohoku University in 2005. The deuterium target data was taken with the tagged photon beam in 2006-2007.

We will report recent results of NKS2 in this paper. Additionally, a status of the upgrade project that gives us larger acceptance and capability of K⁰+Λ coincidence measurement will be repsented.

We plan to have hadron photoproduction experiments by using polarized photon beams at the laser-electron photon facility (LEPS) at SPring-8. We develope a HD (Hydrogen-Deuteride) target as a polarized target for future experiments using both the polarized photon beams and the polarized target since 2005.¹ The HD polarized target will be prodeced at RCNP (Osaka University) and installed in the LEPS facility. Such a double polarization experiment is expected to give important information to investigate the nucleon hidden structure and hadron photoproduction dynamics. We report on the present status of the developement of the polarzed HD target at RCNP.

In the present talk, we review a series of recent investigations on the structure of the baryon antidecuplet, in particular, of the Θ⁺ baryon within the framework of the chiral quark-soliton model. Taking into account the 1/N_c rotational and linear m_s corrections, we calculate the mass splittings of the SU(3) baryons, and the vector and axial-vector transition form factors. We discuss the results in the context of recent experimental data. We also briefly show very recent results of the electromagnetic mass splittings of the baryon antidecuplet in a "model-independent" approach, which will provide a basic setting for the physical mass splittings of the SU(3) baryons.

We study the structure of the σ meson, the lowest-lying resonance of the ππ scattering in the scalar-isoscalar channel, through the softening phenomena associated with the partial restoration of chiral symmetry. We build dynamical chiral models to describe the ππ scattering amplitude, in which the σ meson is described either as the chiral partner of the pion or as the dynamically generated resonance through the ππ attraction. It is shown that the internal structure is reflected in the softening phenomena; the softening pattern of the dynamically generated σ meson is qualitatively different from the behavior of the chiral partner of the pion. On the other hand, in the symmetry restoration limit, the dynamically generated σ meson behaves similarly to the chiral partner.

We study the sigma meson in the QCD sum rule. We use the linear combination of five independent currents. We find that for some cases the Borel mass stability and threshold value stability are both weak, while for some cases not. To know the reason for this we ought to consider the π-π continuum contribution in the phenomenological side of the QCD sum rule. Then we study the stability of the extracted mass against the Borel mass and the threshold value and find the σ(600) mass at 530 MeV ± 40 MeV.

We report a numerical study of two-quark potentials depending on the color-irreducible representation of the SU(3) group by using a quenched-lattice QCD simulation with the Coulomb gauge in the confinement phase. In addition, we display preliminary numerical results for color-decomposed three-quark potentials.

In this talk, we report our present work on the chiral magnetic effect (CME) under a strong magnetic field at low temperature. To this end, we use the instanton vacuum with the finite instanton-number fluctuation Δ, which relates to the nontrivial topological charge Q_t. We compute the vacuum expectation values of the local chiral density 〈ρ_χ〉, chiral charge density 〈n_χ〉 and induced electromagnetic current 〈j_µ〉. We observed that the longitudinal EM current is much larger than the transverse one, |j_⊥/j_∥| ~ Q_t, and the 〈n_χ〉 equals to the |〈j_3,4〉|. It also turns out that the CME becomes insensitive to the magnetic field as T increases, since the instanton effect decreases.

In terms of the decomposition of gauge potential, the two-component dual superconductor theory was obtained based on the SU(2) Yang-Mills theory. We investigate the wall vortices and knots in the multi-component dual superconductor theory.

We study baryons and baryonic matter in holographic QCD with multi-D brane system in type IIA superstring theory. Baryons are described as "Skyrmions" of a four-dimensional meson effective action which is derived from the five-dimensional Yang-Mills theory formulated in holographic QCD. We compare our results with those in the hidden local symmetry approach on the flat space-time, and show that the curved extra-dimension largely changes the roles of (axial) vector mesons for the baryons.

We present in this talk a recent investigation on a unified approach within the framework of a hard-wall model of AdS/QCD. We first study a theoretical inconsistency in existing models. In order to remove this inconsistency, we propose a unified approach in which the mesons and the nucleons are treated on the same footing, the same infrared (IR) cutoff being employed in both fermionic and bosonic sectors. We also suggest a possible way of improving the model by introducing a five-dimensional anomalous dimension.

We discuss the interests and difficulties of the studies of the meson-nucleus bound systems. As recent topics, we briefly explain the research activities of the deeply bound pionic atoms, the η′(958) mesic nuclei, and the ɸ mesic nuclei.

We study the formations of of the η-nucleus systems in the (π,N) reactions with nuclear targets, which can be performed at existing and/or forthcoming facilities, including the Japan Proton Accelerator Research Complex, to investigate the η-nucleus interaction. Based on the N*(1535) dominance in the ηN system, the η-mesic nuclei are suitable systems for the study of in-medium properties of the N*(1535) baryon resonance, such as reduction of the mass difference of N and N* in the nuclear medium, which affects the level structure of the η and N*-hole modes. We find that clear information on the in-medium N*- and η-nucleus interactions can be obtained through the formation spectra of the η-mesic nuclei.

A double-scattering reaction π⁺+d → p+p+η, where an η meson is rescattered, may provide new information on the ηN → ηN scattering. An idea to measure this reaction is proposed. Moreover, experimental search for η-mesic nuclei by the same (π, N) reaction is discussed.

In the study of K^-pp that is the most essential -nuclear system, the coupling dynamics of and πΣN is important. In case that the K^-pp is considered as a coupled channel system, we need to treat it as a resonant state, because the πΣN channel is an open channel. We propose the application of the Complex Scaling Method (CSM), which is a powerful tool for the treatment of resonant states, to the study of K^-pp. In this article, we report the result of our test calculation for the two-body case, system corresponding to Λ(1405) studied with a phenomenological potential.

We consider baryon chiral multiplet mixing as an explanation of the nucleon's isovector and flavor-singlet axial coupling constants. Three-quark nucleon interpolating fields in QCD have well-defined U_A(1) and SU_L(3)×SU_R(3) chiral transformation properties, which means that the axial currents made from these fields have well defined flavor singlet and flavor octet , couplings. There are two independent local baryon fields, the (the "Ioffe current") and the [(8, 1) ⊕ (1, 8)]. These two fields together with their (non-local) chiral "mirrors", and [(1, 8) ⊕ (8, 1)] allow four possible scenarios of mixing with the non-local [(6, 3)⊕(3, 6)] interpolating field. Chiral multiplet mixing then predicts the nucleon flavor-singlet axial coupling , with a value that depends on the chiral multiplet that is admixed to the [(6, 3)⊕(3, 6)] one. In this talk we explore all two- and three-state mixing scenarios and show that one can fit the observed data reasonably well, though not perfectly.

We present preliminary results on the measurement of ɸp scattering length from the ɸ photoproduction near its threshold energy at LEPS/SPring-8.

We present in this talk a recent investigation on the γp → ɸp reaction within the effective Lagrangian approach. We introduce the exchange of a particle with exotic quantum number J^PC = 1^-+ and loop corrections with K^±. We compare the results with the experimental data and discuss them.

We investigate γp → K*⁺Λ reaction within a Regge approach. For the gauge invariance of the scattering amplitude, we reggeize the s-channel and contact term amplitudes as well as the t-channel amplitude. We obtain the decreasing behavior of the total cross section as the CLAS's preliminary data show. We also calculate spin density matrices, and find clear differences between our Regge model and the previous Feynman (isobar) model.

Recently, the CLAS collaboration at Thomas Jefferson Nation Acceleration Facility reported the total cross section data for K* photoproduction, and found that the t-channel K exchange dominates the production amplitudes at small scattering angles. The measurement of forward-angle beam spin asymmetries for this reaction, where the theoretical calculations show an unambiguous signal, would establish the role of the κ(800). We have measured the photon beam asymmetry for the γp → K*⁰Σ⁺ reaction on a Liquid Hydrogen target in the energy from threshold to 3.0 GeV by using a linearly polarized photon beam at SPring-8.

We study baryons in dense matter using a holographic QCD (hQCD) model. Baryons are introduced as the bulk Dirac field in five dimensional anti de Sitter (AdS) space. We turn on the baryon number density ρ_B by a standard AdS/CFT dictionary and the scalar density ρ_s as a bi-fermion condensate of the nucleon field in hQCD. We calculate the in-medium mass of the nucleon and observe that the mass decreases with increasing baryon number density.

The contribution of the R-parity violating (RPV) minimal supersymmetric standard model (MSSM) to the neutron beta decay is discussed. The RPV effects contribute to the scalar interaction at the tree level. From it, we construct the effective interaction by using the nucleon mass difference and give its contribution to the angular correlations of the neutron beta decay within the recent phenomenological limits, i.e. the experimental result of the R correlation of the neutron beta decay given by PSI and the analyses of the Superallowed Fermi transitions.

We study the structure of pionic atoms in ¹²¹Sn, for which a new experiment will be performed at RIKEN RI Beam Factory. We evaluate numerically the effective nuclear densities probed by pion and potential parameter dependence of the binding energies and widths.

We propose a new theoretical approach to calculate nuclear structure using bare nuclear interaction, in which the tensor and short-range correlations are described by using the tensor optimized shell model (TOSM) and the unitary correlation operator method (UCOM), respectively. We compare the obtained results using TOSM+UCOM for ⁴He with the rigorous calculation.

The α+⁸He low-energy reactions and the exotic structures of ¹²Be are studied by the application of the generalized two-center cluster (α+α+4N) model. In the two-neutron transfer reactions, α+⁸He_g.s. → ⁶He_g.s.+⁶He_g.s., a resonant peak with J^π=0⁺ appears around E ~ 1.3 MeV above the ⁶He_g.s.+⁶He_g.s. threshold as the result of the formation of the covalent superdeformation, which has a hybrid structure of covalent and ionic configurations for the valence neutrons. The covalent superdeformed state becomes an isomeric state with a sharp width of Γ ~ 400 keV. Experimental conditions to identify the isomeric state are also discussed.

The density functional theory (DFT) with a minimal number of parameters allows a very successful phenomenological description of ground state properties of nuclei all over the periodic table. Recent progresses on the application of the covariant density functional theory as well as its extensions by the group in Beijing for a series of interests and hot topics in nuclear astrophysics and nuclear structure are reviewed, including the rapid neutron-capture process, Th/U chronometer, halo and giant halo in density dependent relativistic Hartree-Fock-Bogoliubov, and neutron halo in deformed nuclei.

The α-decay half-lives of superheavy nuclei around the N = 152 shell gap have been systematically investigated using theoretical Q values. These theoretical Q values are extracted from the local formula of binding energies for heavy and superheavy nuclei. Exact calculations are performed in two ways: the unified formula of half-lives for α decay and cluster radioactivity, and the generalized density-dependent cluster model. It is found that the available experimental α-decay half-lives are well reproduced in this two ways. Based on this fact, some useful predictions of α-decay half-lives are made for still unknown superheavy nuclei, which may guide future experiments.

Low density states near the 3α and 4α breakup threshold in ¹²C and ¹⁶O, respectively, are discussed in terms of the α-particle condensation. Calculations are performed in OCM (Orthogonality Condition Model) and THSR (Tohsaki-Horiuchi-Schuck-Röpke) approaches. The state in ¹²C and the state in ¹⁶O are shown to have dilute density structures and give strong enhancement of the occupation of the S-state c.o.m. orbital of the α-particles. The state in ¹⁶O has a large component of configuration, which is another reliable evidence of the state to be of 4α condensate nature. The possibility of the existence of α-particle condensed states in heavier nα nuclei is also discussed.

In constructing the dense matter equation of state (EOS), it is desired to respect both chiral symmetry and hypernuclear physics. In dense matter, strangeness is expected to play a decisive role and the partial restoration of chiral symmetry would modify the hadron properties. For chiral symmetry side, We have recently developed the chiral SU(2) symmetric RMF model with logarithmic sigma potential derived in the strong coupling limit (SCL) of the lattice QCD. In this SCL model, we can describe not only symmetric nuclear matter but also bulk properties of finite nuclei. We find that the EOS of symmetric matter is softened by the scalar meson with hidden strangeness, which couples with sigma meson through the determinant interaction. In this paper, we present this RMF model including chiral SU(3) potential and its results. We discuss the importance of hyperon in neutron star in this chiral SU(3) RMF model and show an effect to nuclear star maximum mass by introducing this potential. We also inquire the effect of meson-meson-baryon coupling which is corresponding to density dependent couplings.

Cluster structures in the excited states of ¹³C have been investigated by using a microscopic 3α+n model. We have found two excited rotational bands that have developed α cluster structures. Unlike the dilute cluster-gas structure of state in ¹²C, three α clusters in the lower rotational band has bended linear-chain like configuration.

Algebraic nuclear models have successfully applied for various mass regions. In ¹²C, we couple this model space with treatment of the so-called complex scaling method for resonance states. We use the Sp(2,R)_z algebra to create ladder states on SU(3) bases which have large harmonic oscillation quanta. One advantage of this method is that it is possible naturally to extend to Nα systems. The wave function is semi-microscopic and satisfies the Pauli principle (orthogonal to the Pauli forbidden states). We study basic properties of this wave function.

We develop the new antisymmetrized molecular dynamics (AMD) method which makes us perform the AMD calculations starting from the bare nuclear interactions. In this framework, the G-matrix and the single-particle energies of AMD are determined from the bare interactions self-consistently without any corrections. In this paper, we present the applicability of this method to describe not only the ground states but also the excited states for some light nuclei, especially the excited state in ¹²C which is not solved sufficiently by the present shell model approaches.

We describe a model for pion production off nucleons and coherent pions from nuclei induced by neutrinos in the 1 GeV energy regime. Besides the dominant Δ pole contribution, it takes into account the effect of background terms required by chiral symmetry. Moreover, the model uses a reduced nucleon-to-Δ resonance axial coupling, which leads to coherent pion production cross sections around a factor two smaller than most of the previous theoretical estimates. Nuclear effects like medium corrections on the Δ propagator and final pion distortion are included.

We report on recent results obtained with the extended-soft-core (ESC) interactions. The ESC-model gives a unified description of nucleon-nucleon (NN), hyperon-nucleon (YN), and hyperon-hyperon (YY), using (broken) flavor SU_f(3)-symmetry. This is achieved by fitting simultaneously NN-, YN-, and YY-data with single sets of meson parameters. The dynamics is derived from (i) one-boson-exchange (OBE), (ii) two-meson-exchanges (TME), and (iii) meson-pair-exchange (MPE). The changes with respect to the previous versions are explained, and the properties of the meson parameters are commented on. Emphasized are the relations with the quark-model (QM), QCD, chiral-symmetry, and the quark-structure of the baryons. The NN, YN, and YY results for this model are excellent. This is marked particularly by the NN-results, namely and 1.135 for respectively ESC08a and ESC08b. It is to be noted that the solutions suggest the existence of an S=-2 deuteron state in the ΞN(³S₁,T = 1)-channel. The predictions for the S=-3,-4-channels include the existence of a bound ¹S₀(ΞΞ,T = 1)- state.

As one of the typical sd-shell hypernuclei, the positive- and negative-parity energy levels of have been calculated to investigate structures of low-lying states within the standard shell model. In addition to the conventional NN interactions, the ΛN G-matrix interactions derived from the Nijmegen Model-D and NSC97f potentials are employed.

Detailed structure calculations in , and are performed within the framework of the microscopic of four-body cluster models. We adopted effective ΞN interactions derived from the Nijmegen interaction models, which give rise to substantially attractive Ξ-nucleus potentials in accordance with the experimental indications. and are predicted to have bound states. we propose to observe the bound states in future (K^-,K⁺) experiments using ⁷Li and ¹⁰B targets in addition to the standard ¹²C target. The experimental confirmation of these states will provide information on the spin- and isospin-averaged ΞN interaction.

Large-amplitude oblate-prolate shape coexistence dynamics in proton-rich Se and Kr isotopes is analyzed using the five-dimensional quadrupole collective Hamiltonian. The potential and inertial functions in the collective Hamiltonian are calculated using the constrained Hartree-Fock-Bogoliubov (CHFB) equation and the local quasiparticle random-phase approximation (LQRPA). The excitation spectra and the electric quadrupole transitions between the low-lying states in ⁶⁸Se are calculated by solving the collective Schrödinger equation, and the shape mixing dynamics in the low-lying collective states are discussed.

We study the role of pion on finite nuclei using the relativistic chiral mean field (RCMF) model. We present how to treat the strong tensor correlation in a consistent way to the nuclear many-body problems and show calculated results in the RCMF model.

The present status of the microscopic theory for complex optical potentials of nucleus-nucleus systems is reviewed in the present talk, including the brief history and the latest achievement in the theoretical analysis of elastic scattering of light heavy-ion systems on the basis of double-folding model with the use of the CEG07 G-matrix interaction recently proposed by the present authors, with a special emphasis upon the role of the three-body force.

In this talk, we propose applying the complex-scaling method to CDCC, where the internal coordinate and momentum of projectile nucleus are complex-scaled. We show that the continuous S matrix element of breakup reaction is obtained without smoothing function.

We investigated ¹⁴C with β-γ constraint antisymmetrized molecular dynamics coupled with the generator coordinate method (β-γ constraint AMD+GCM). Above the ground band, three excited bands with the developed three-α-cluster structures were suggested. Characteristic structures such as a triaxial structure and a linear-chain structure appear in the excited bands. By estimating ¹⁰Be+β components in the obtained ¹⁴C states, it is suggested that the experimental state at 18.6 MeV is a candidate of the theoretical 4⁺ linear-chainlike state.

Nuclear matter is studied by using beyond relativistic Hartree-Fock (RHF) model with the realistic nucleon-nucleon (NN) interaction. We use the unitary correlation operator method (UCOM) to treat the strong repulsive interaction in the short-range region between two nucleons. We find that the equation of state (EOS) of pure neutron matter is completely comparable with the results of Dirac-Brueckner-Hartree-Fock (DBHF) theory. However, for the symmetric nuclear matter, the EOS is largely different from the DBHF result particularly in the low density region.

We study theoretically the elastic scattering of ⁸B from ¹²C at E_lab = 95MeV, where the projectile has a three cluster structure α+³He+p. We treat the halo proton in ⁸B in the adiabatic recoil approximation¹ and take into account the excited states of ⁷Be including resonance states by a coupled channel method with consideration of the cluster structure. We reproduce the differential cross section of elastic scattering of ⁸B from ¹²C. It turns out that the excitaion to the resonance state of ⁷Be is important.

We study the mechanism of electromagnetic noise generation in standard two-conductor transmission-line circuit due to its coupling to the circumstance by using the newly developed multiconductor transmission-line theory. We discuss then how to reduce the electromagnetic noise by introducing the third line and arrange all the electric loads symmetrically around the third line.

With the maturity of high-power laser technology, we can realize an extremely high intensity of photons in a tiny space. About 10 kJ of 1eV photons (10²²photons) can be squeezed in a space of several micro-meter during 10 fs (10^-14s). This means the density of photons of n_photon=10³⁴/cm³. Photon is boson and can be squeezed to a tiny space. We expect that we can design unique experiments of the collective effects of elementary particles and such lasers can also be used for a new type of experiments. The physics will be more wider with the combination of the conventional accelerators. In the present paper, I briefly describe what we have carried out as academic research related to so-called laser nuclear physics.

LIST OF PARTICIPANTS