Antisymmetry in Strangeness -1 and -2 Three-Baryon Systems

Using the generalized Pauli principle by adding particle labels to the usual space and spin labels a symmetric Hamiltonian and a corresponding antisymmetric wavefunction is constructed for systems of three baryons in the strangeness sectors $S=-1$ and -2. Applications are the $\Xi NN-\Lambda\Lambda N$ and $NN\Lambda -NN\Sigma$ systems. Minimal sets of generalized coupled Faddeev equations for breakup and rearrangement operators as well as (possible) bound states are derived which have the ordinary Pauli principle among identical particles built in. The equations found confirm our previous sets of coupled Faddeev equations for those systems whose derivation was carried through for distinguishable particles and not using the generalized Pauli principle.Comment: 28 pages and 2 figure

Magnetic-Field-Induced Mott Transition in a Quasi-Two-Dimensional Organic Conductor

We investigated the effect of magnetic field on the highly correlated metal near the Mott transition in the quasi-two-dimensional layered organic conductor, $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Cl, by the resistance measurements under control of temperature, pressure, and magnetic field. It was demonstrated that the marginal metallic phase near the Mott transition is susceptible to the field-induced localization transition of the first order, as was predicted theoretically. The thermodynamic consideration of the present results gives a conceptual pressure-field phase diagram of the Mott transition at low temperatures.Comment: 4 pages, 4 figure

Neutral kaon photoproduction on the deuteron

Neutral kaon photoproduction on the deuteron has been investigated by including the final state effects and compared with the experimental data. Comparison shows that the models used in this calculation can reproduce the data in the $\Sigma$ channel regions fairly well but still give over predictions in the $\Lambda$ channel. It seems that the tensor target asymmetries are more suitable for studying the final state effects. The extractions of the elementary photoproduction amplitude are also demonstrated.Comment: 6 pages, 6 figures, talk given by A. Salam at Fourth Asia-Pacific Conference on Few-Body Problems in Physics 2008 (APFB08), Depok, Indonesia, August 19-23, 200

Field-induced staggered magnetic moment in the quasi-two-dimensional organic Mott insulator κ\kappa-(BEDT-TTF)2_{2}Cu[N(CN)2_{2}]Cl

We investigated the magnetism under a magnetic field in the quasi-two-dimensional organic Mott insulator $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Cl through magnetization and $^{13}$C-NMR measurements. We found that in the nominally paramagnetic phase (i.e., above N\'eel temperature) the field-induced local moments have a staggered component perpendicular to the applied field. As a result, the antiferromagnetic transition well defined at a zero field becomes crossover under a finite field. This unconventional behavior is qualitatively reproduced by the molecular-field calculation for Hamiltonian including the exchange, Dzyaloshinsky-Moriya (DM), and Zeeman interactions. This calculation also explains other unconventional magnetic features in $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Cl reported in the literature. The present results highlight the importance of the DM interaction in field-induced magnetism in a nominally paramagnetic phase, especially in low-dimensional spin systems.Comment: 11 pages, 12 figures, selected for Editors' Suggestion

Nuclear Reactions: A Challenge for Few- and Many-Body Theory

A current interest in nuclear reactions, specifically with rare isotopes concentrates on their reaction with neutrons, in particular neutron capture. In order to facilitate reactions with neutrons one must use indirect methods using deuterons as beam or target of choice. For adding neutrons, the most common reaction is the (d,p) reaction, in which the deuteron breaks up and the neutron is captured by the nucleus. Those (d,p) reactions may be viewed as a three-body problem in a many-body context. This contribution reports on a feasibility study for describing phenomenological nucleon-nucleus optical potentials in momentum space in a separable form, so that they may be used for Faddeev calculations of (d,p) reactions.Comment: to appear in the Proceedings of HITES 2012: Conference on `Horizons of Innovative Theories, Experiments, and Supercomputing in Nuclear Physics', June 4-7, 2012, New Orleans, Louisian

The Juelich hyperon-nucleon model revisited

A one-boson-exchange model for the hyperon-nucleon (\Lambda N, \Sigma N) interaction is presented. The model incorporates the standard one boson exchanges of the lowest pseudoscalar and vector meson multiplets with coupling constants fixed by SU(6) flavor symmetry relations. As the main new feature of the model, the contributions in the scalar--isoscalar (\sigma) and vector--isovector (\rho) exchange channels are now constrained by a microscopic model of correlated \pi\pi and K \bar K exchange. Additional short-ranged ingredients of the model in the scalar--isovector (a_0) and scalar--isospin-1/2 (\kappa) channels are likewise viewed as arising from meson-meson correlations but are treated phenomenologically. With this model a satisfactory reproduction of the available hyperon-nucleon data can be achieved.Comment: 24 pages, 13 figures, some modifications to text, several references added, some figures corrected, to appear in Phys. Rev.

Quark-Model Baryon-Baryon Interaction and its Applications to Hypernuclei

The quark-model baryon-baryon interaction fss2, proposed by the Kyoto-Niigata group, is a unified model for the complete baryon octet (B_8=N, Lambda, Sigma and Xi), which is formulated in a framework of the (3q)-(3q) resonating-group method (RGM) using the spin-flavor SU_6 quark-model wave functions and effective meson-exchange potentials at the quark level. Model parameters are determined to reproduce properties of the nucleon-nucleon system and the low-energy cross section data for the hyperon-nucleon scattering. Due to the several improvements including the introduction of vector-meson exchange potentials, fss2 has achieved very accurate description of the NN and YN interactions, comparable to various one-boson exchange potentials. We review the essential features of fss2 and our previous model FSS, and their predictions to few-body systems in confrontation with the available experimental data. Some characteristic features of the B_8 B_8 interactions with the higher strangeness, S=-2, -3, -4, predicted by fss2 are discussed. These quark-model interactions are now applied to realistic calculations of few-body systems in a new three-cluster Faddeev formalism which uses two-cluster RGM kernels. As for the few-body systems, we discuss the three-nucleon bound states, the Lambda NN-Sigma NN system for the hypertriton, the alpha alpha Lambda system for 9Be Lambda, and the Lambda Lambda alpha system for 6He Lambda Lambda.Comment: 20 pages, 12 figures, 18th Nishinomiya Yukawa Memorial Symposium on Strangeness in Nuclear Matter, 4 - 5 December 2003, Nishinomiya, Japan. (to be published in Prog. Theor. Phys. Suppl.

Addendum: Triton and hypertriton binding energies calculated from SU_6 quark-model baryon-baryon interactions

Previously we calculated the binding energies of the triton and hypertriton, using an SU_6 quark-model interaction derived from a resonating-group method of two baryon clusters. In contrast to the previous calculations employing the energy-dependent interaction kernel, we present new results using a renormalized interaction, which is now energy independent and reserves all the two-baryon data. The new binding energies are slightly smaller than the previous values. In particular the triton binding energy turns out to be 8.14 MeV with a charge-dependence correction of the two-nucleon force, 190 keV, being included. This indicates that about 350 keV is left for the energy which is to be accounted for by three-body forces.Comment: 4 pages, 1 figur