Narrow Results

K⁻pn and K⁻pp bound states are searched for at SPring-8/LEPS in the d(γ, K⁺) and d(γ, K⁺π⁻) reactions with photon energies from 1.5 to 2.4 GeV. The data was collected during the 2002-2003 run period utilizing liquid hydrogen and liquid deuterium targets. Using the K⁺ and K⁺π⁻ missing mass spectra from the deuteron, we hope to determine upper limits for K⁻pn and K⁻pp bound state production.

Observables in proton-deuteron scattering are sensitive probes of the nucleon-nucleon interaction and three-nucleon force effects. Several facilities, including the KVI, allow a detailed study of few-nucleon interactions below the pion-production threshold exploiting polarized proton and deuteron beams. In this contribution, some recent results are discussed and interpreted exploiting rigorous Faddeev calculations. Furthermore, experimental inconsistencies between two measurements of the cross section in elastic proton-deuteron scattering at 135 MeV/nucleon are reviewed.

Cross section and analyzing power A_y of reaction at were measured and large disagreements with 3N calculations were found especially at forward angles. Effects of 2π3NF are too small to explain the discrepancy. To microscopically investigate the discrepancy, a ²H(p, pp)n experiment is planned.

We made again an experiment of pd radiative capture at , and obtained A_xx, A_yy and A_zz (= -A_xx - A_yy) data using a newly-developed data-analysis method of high detection efficiency. Re-analysis of previous data on A_xx and A_yy was also made using a new method. All the new and previous data at 197 MeV agree to each other, and A_xx anomaly has been confirmed.

The D+D → ⁴He reaction can be one of the methods to count the magnetic monopole. In order to prove this, the mechanism of bound state of nucleons and monopole system is clarified. We calculated bound state of nucleon-monopole system by using the Jacobi-coordinate bases antisymmetrized molecular dynamics (or JAMD) method. This calculation is done to show the efficiency of JAMD as a first step of main subject. The binding energy of neutron and proton in the magnetic monopole field is calculated. Our results are compared with those of analytical solution.

The universal character of non-relativistic large three-body bosonic systems is addressed, with focus on highly interesting situations that occur in low-energy nuclear and atomic physics. Investigations on the trajectory of the first excited Efimov state, in a renormalized zero-range three-body model for a system with two bound and one virtual two-body subsystems, are reported. The approach is applied to n-n-¹⁸C, where the n - n virtual energy and the three-body ground state are kept fixed. It is shown that the real part of the elastic s-wave phase-shift () presents a zero, or a pole in , when the system has an Efimov excited or virtual state. A brief discussion is given on the relevance of the approach for ultracold atom physics with tunable scattering lengths.

We present a Faddeev-type coupled integrodifferential equations describing unequal mass A-particle systems. The equations are obtained by assuming an expansion of the A-particle wave function in Faddeev amplitudes which, in turn, are expanded in terms of Potential Harmonics. By projecting the resulting system on r_ij-space we obtained a system of coupled equations which can be used to study multi-strange hypernuclei.

We attempt at describing the particle-hole and cluster excitations for A ~ 16 nuclei in a single scheme of a ¹²C core plus few-nucleon model. A nucleon-¹²C potential is derived based on a collective model taking into account the core excitation and its parameters are determined to reproduce the low-lying spectrum of ¹³C. The model is tested in three- and four-body systems, ¹⁴C, ¹⁴N and ¹⁵C. Preliminary results of the five-body systems for ¹⁶C and ¹⁶O are reported.

We investigated the dependence of the K^-d scattering length on two models of interaction, providing one or two poles for the Λ(1405) resonance. The system is described by coupled-channels Faddeev equations in AGS form. The two-body interaction models reproduce all existing experimental data on K^-p scattering and K^-p atom level shift. The comparison with several approximations, commonly used for such calculations, was done.

The radiative capture process np→dγ is considered within the framework of a recently developed six-quark dressed-bag model for the nucleon-nucleon interaction. The calculations presented here include both the nucleon current and the meson-exchange current contributions. The latter uses short-range hadronic form factors for the pion exchange currents consistent with the soft cut-off parameter Λ_πNN from the NN-potential. Contributions of the pion exchange current and Δ-isobar current to the total cross-section still cannot explain the discrepancy between the theoretical and experimental cross-sections. Possibilities for new types of meson exchange currents associated with chiral fields inside multi-quark dressed-bag states in nuclei are discussed.

The light double $\mathrm{\Lambda }$ hypernuclei, ${}_{\mathrm{\Lambda }\mathrm{\Lambda }}^4\mathrm{\text{H}}$ and ${}_{\mathrm{\Lambda }\mathrm{\Lambda }}^6\mathrm{\text{He}}$, are studied as three-body $\mathrm{\Lambda }\mathrm{\Lambda }d$ and $\mathrm{\Lambda }\mathrm{\Lambda }\alpha$ cluster systems in halo/cluster effective field theory at leading order. We find that the $\mathrm{\Lambda }\mathrm{\Lambda }d$ system in spin-0 channel does not exhibit a limit cycle whereas the $\mathrm{\Lambda }\mathrm{\Lambda }d$ system in spin-1 channel and the $\mathrm{\Lambda }\mathrm{\Lambda }\alpha$ system in spin-0 channel do. The limit cycle is associated with the formation of bound states, known as Efimov states, in the unitary limit. For the $\mathrm{\Lambda }\mathrm{\Lambda }d$ system in the spin-0 channel we estimate the scattering length $a_0$ for $S$-wave $\mathrm{\Lambda }$ hyperon–hypertriton scattering as $a_0=16.0\pm 3.0$fm. We also discuss that studying the cutoff dependences in the $\mathrm{\Lambda }\mathrm{\Lambda }d$ and $\mathrm{\Lambda }\mathrm{\Lambda }\alpha$ systems, the bound state of ${}_{\mathrm{\Lambda }\mathrm{\Lambda }}^4\mathrm{\text{H}}$ is not an Efimov state but formed due to a high energy mechanism whereas that of ${}_{\mathrm{\Lambda }\mathrm{\Lambda }}^6\mathrm{\text{He}}$ may be regarded as an Efimov state.

We review the status as regards to the existence of three- and four-body bound states made of neutrons and $\mathrm{\Lambda }$ hyperons. For interesting cases, the coupling to neutral baryonic systems made of charged particles of different strangeness has been addressed. There are strong arguments showing that the $\mathrm{\Lambda }nn$ system has no bound states. $\mathrm{\Lambda }\mathrm{\Lambda }nn$ strong stable states are not favored by our current knowledge of the strangeness $-1$ and $-2$ baryon–baryon interactions. However, a possible ${\mathrm{\Xi }}^{-}t$ quasibound state decaying to $\mathrm{\Lambda }\mathrm{\Lambda }nn$ might exist in nature. Similarly, there is a broad agreement about the nonexistence of $\mathrm{\Lambda }\mathrm{\Lambda }n$ bound states. However, the coupling to $\mathrm{\Xi }NN$ states opens the door to a resonance above the $\mathrm{\Lambda }\mathrm{\Lambda }n$ threshold.

In this contribution we present symmetry arguments that can be applied to study the stability of four-quark systems with two different masses. The role played by different symmetry breaking effects and the non-Abelian algebra of color forces is discussed in detail. In the particular case of hidden-flavor all-heavy four-quark states, $QQ\bar{Q}\bar{Q}$, the system becomes unstable for standard color-additive models. Differences and similarities between $Qq\bar{Q}\bar{q}$ and $QQ\bar{q}\bar{q}$ configurations are presented. In the latter case, its stability when the mass ratio $M/m$ increases was established almost forty years ago. In the former case, we find a kind of metastability between the lowest threshold, $(Q\bar{Q})-(q\bar{q})$ and the highest one, $(Q\bar{q})-(\bar{Q}q)$.

The status of realistic calculations of nuclear generalized parton distributions, entering the theoretical description of coherent deeply virtual Compton scattering off nuclei, is reviewed for trinucleons and for ⁴He, also in view of forthcoming measurements at the Jefferson Laboratory and at the future Electron Ion Collider.

An overview over the field of few-nucleon systems is presented. Special emphasis is laid on the construction of a unified approach to hadronic and electromagnetic reactions on few-nucleon systems, necessary for studying the borderline between quark-gluon and effective descriptions. We briefly outline the Lorentz integral transform (LIT) method which offers a unique possibility to tackle this ambitious task.

The photodisintegration cross section of ⁴He is calculated using the realistic nucleon-nucleon potential Argonne V18 (AV18) and the three-body force Urbana IX (UIX). Final State interaction is taken into account via the Lorentz Integral Transform method. A comparison with other potential models and with the available experimental data is discussed.

The energies and the wave functions of the ground states of ³H, ^3,4,6He, ⁶Li, ⁹Be nuclei have been calculated by Feynman’s continual integrals method. Results demonstrate overall satisfactory agreement with the experimental data.

Experimental investigation of the nuclei far from the region of nuclear stability deal with continuous spectra of many overlapping states. Traditional methods for extraction of nuclear structure becomes insufficient and alternative approaches are needed. Treatment of cluster correlations in nuclei represent powerful tool for studies of exotic nuclear systems. The employment of the method is illustrated on two examples: ⁶Be and ¹⁰He.

This manuscript sheds light on the puzzle created by the finding of two resonances with same quantum numbers and very similar mass but which possess very different decay properties. One of them, f₀(1790), has been found in the J/Ψ → φπ⁺π⁻ process while the other, f₀(1800), in J/Ψ → γωφ. As we shall discuss in this manuscript, our studies show that these two states are distinct to each other but only one of them is a new state, while the other one is the manifestation of the known f₀(1710). We also provide an explanation for the different decay properties of these states.