We study the interesting problem of whether it is possible to distinguish composite from elementary particles. In particular we generalize a model-independent approach S. Weinberg case unstable This allows us apply our formalism a0(980) and f0(980) resonances address question these particles are predominantly genuine, confined quark states (of $\bar q q$ or $qq\bar q\bar structure) governed by mesonic components.

A separable representation of the Paris potential is constructed by means Ernst-Shakin-Thaler method. The resulting interactions represent a good approximation on-shell as well off-shell properties potential. Their form factors are composed rational functions not too complicated for today's computer codes few-body systems. various features nucleon-nucleon force discussed together with first results obtained these potentials elastic electron-deuteron and nucleon-deuteron scattering.

A one-boson-exchange model for the hyperon-nucleon (\Lambda N, \Sigma N) interaction is presented. The incorporates standard one boson exchanges of lowest pseudoscalar and vector meson multiplets with coupling constants fixed by SU(6) flavor symmetry relations. As main new feature model, contributions in scalar--isoscalar (\sigma) vector--isovector (\rho) exchange channels are now constrained a microscopic correlated \pi\pi K \bar exchange. Additional short-ranged ingredients...

Abstract The $$\varLambda N$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Λ</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:math> and $$\varSigma xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Σ</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:math> interactions are considered at next-to-leading order in SU(3) chiral effective field theory. Different options for the low-energy constants that determine strength of contact explored. Two variants analysed...

A hyperon-nucleon potential for the strangeness $S=-1$ sector ($\Lambda N$, $\Sigma N$) up to third order in chiral expansion is presented. SU(3) flavor symmetry imposed constructing interaction, however, explicit breaking by physical masses of pseudoscalar mesons and leading-order contact terms taken into account. novel regularization scheme employed which has already been successfully used studies nucleon-nucleon interaction within effective field theory high orders. An excellent...

Abstract Separation energies of light $$\varLambda $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Λ</mml:mi> </mml:math> hypernuclei ( $$A\le 5$$ <mml:mrow> <mml:mi>A</mml:mi> <mml:mo>≤</mml:mo> <mml:mn>5</mml:mn> </mml:mrow> ) and their theoretical uncertainties are investigated. Few-body calculations performed within the Faddeev-Yakubovsky scheme no-core shell model. Thereby, modern up-to-date nucleon-nucleon, three-nucleon hyperon-nucleon potentials derived chiral...

We investigate the nature of near-threshold enhancement in $p\overline{p}$ invariant-mass spectrum reaction $J/\ensuremath{\Psi}\ensuremath{\rightarrow}\ensuremath{\gamma}p\overline{p}$ reported recently by BES Collaboration. Using J\"ulich $N\overline{N}$ model we show that mass dependence close to threshold can be reproduced $S$-wave final state interaction isospin $I=1$ within Watson-Migdal approach. However, because our poor knowledge and mechanism view controversal situation decay...

This work provides the first combined analysis of low-energy pΛ scattering, considering both cross section and correlation data. The obtained results establish most stringent constraints to date on two-body interaction, pointing a weaker attraction than so far accepted. best set scattering lengths for spin singlet triplet are found range from f0,f1=(2.1,1.56) (3.34,1.18)fm. With chiral NY potential fine-tuned those parameters, in-medium properties Λ explored depth...

The $\ensuremath{\pi}N$ interaction is studied within a meson-exchange model and in coupled-channels approach which includes the channels $\ensuremath{\pi}N$, $\ensuremath{\eta}N$, as well three effective $\ensuremath{\pi}\ensuremath{\pi}N$ channels, namely, $\ensuremath{\rho}N$, $\ensuremath{\pi}\ensuremath{\Delta}$, $\ensuremath{\sigma}N$. Starting out from an earlier of J\"ulich group systematic improvements dynamics some technical aspects are introduced. With new excellent quantitative...

We give a modified separable representation of the Paris potential, which is to remedy shortcomings an earlier parametrization in $^{1}\mathrm{S}_{0}$ and $^{3}\mathrm{P}_{0}$ partial waves. In particular, present does not lead unphysical bound states at very large negative energies as encountered previously. Still, it provides for good approximation on-shell well off-shell properties potential.

A separable representation of a boson-exchange nucleon-nucleon potential is constructed via the Ernst-Shakin-Thaler method. The resulting interactions provide for satisfactory approximation on-shell as well off-shell properties Bonn potential. Their form factors are composed rational functions suitable today's computer codes few-body systems. First results obtained with these potentials elastic nucleon-deuteron scattering presented.

The reaction $e^+e^- \to \bar \Lambda \Lambda$ is investigated for energies close to the threshold. Specific emphasis put on role played by interaction in final $\bar system which taken into account rigorously. For that a variety of potential models employed have been constructed analysis p past. enhancement effective form factor threshold, seen pertinent experiments, reproduced. Predictions $\Lambda$ electromagnetic factors $G_M$ and $G_E$ timelike region spin-dependent observables such as...

Results for the antinucleon-nucleon $$ \left(\overline{N}\;N\right) interaction obtained at next-to-next-to-next-to-leading order in chiral effective field theory (EFT) are reported. A new local regularization scheme is used pion-exchange contributions that has been recently suggested and applied a pertinent study of N force within EFT. Furthermore, an alternative strategy estimating uncertainty utilized no longer depends on variation cutoffs. The low-energy constants associated with arising...