No Arabic abstract
The kaonic clusters $K^{-}K^{-}p$ and $ppK^{-}$ are described based on the configuration space Faddeev equations for $AAB$ system. The $AB$ interaction is given by isospin-dependent potentials. For this isospin model, we show that the relation $leftvert E_{3}(V_{AA}=0)rightvert~<~2leftvert E_{2}rightvert$ is satisfied when $E_{2}$ is the binding energy of the $AB$ subsystem and $E_{3}(V_{AA}=0)$ is the three-body binding energy when interaction between identical particles is omitted, $V_{AA}=0$. For the $NN{bar K}$ system, taking into account weak attraction of $NN$ interaction the relation leads to the evaluation $|E_3|le 2|E_2|$. The isospinless model for the kaonic clusters based on the isospin averaged $N{bar K}$ potential demonstrates the opposite relation $leftvert E_{3}(V_{AA}=0)rightvert~>~2leftvert E_{2}rightvert$. The isospin given charge formalism is presented for $NN{bar K}$ cluster. This formalism is related to isospin model by unitary transformation of the isospin basis. An interpretation of the particle representation for $NN{bar K}$ system is proposed.
We evaluate the mass polarization term of the kinetic-energy operator for different three-body nuclear $AAB$ systems by employing the method of Faddeev equations in configuration space. For a three-boson system this term is determined by the difference of the doubled binding energy of the $AB$ subsystem $2E_{2}$ and the three-body binding energy $E_{3}(V_{AA}=0)$ when the interaction between the identical particles is omitted. In this case: $leftvert E_{3}(V_{AA}=0)rightvert >2leftvert E_{2}rightvert$. In the case of a system complicated by isospins(spins), such as the kaonic clusters $ K^{-}K^{-}p$ and $ppK^{-}$, the similar evaluation impossible. For these systems it is found that $leftvert E_{3}(V_{AA}=0)rightvert <2leftvert E_{2}rightvert$. A model with an $AB$ potential averaged over spin(isospin) variables transforms the later case to the first one. The mass polarization effect calculated within this model is essential for the kaonic clusters. Besides we have obtained the relation $|E_3|le |2E_2|$ for the binding energy of the kaonic clusters.
We report quantum Monte Carlo calculations of single-$Lambda$ hypernuclei for $A<50$ based on phenomenological two- and three-body hyperon-nucleon forces. We present results for the $Lambda$ separation energy in different hyperon orbits, showing that the accuracy of theoretical predictions exceeds that of currently available experimental data, especially for medium-mass hypernuclei. We show the results of a sensitivity study that indicates the possibility to investigate the nucleon-isospin dependence of the three-body hyperon-nucleon-nucleon force in the medium-mass region of the hypernuclear chart, where new spectroscopy studies are currently planned. The importance of such a dependence for the description of the physics of hypernuclei, and the consequences for the prediction of neutron star properties are discussed.
In the model of low-energy bar-K N interactions near threshold (EPJA 21, 11 (2004); 25, 79 (2005)) we calculate isospin-breaking corrections to the energy level displacement of the ground state of kaonic hydrogen, investigated by Meissner, Raha and Rusetsky (EPJC 35, 349 (2004)) within the non-relativistic effective Lagrangian approach based on ChPT by Gasser and Leutwyler. Our results agree well with those by Meiss ner et al.. In addition we calculate the dispersive corrections, caused by the transition K^-p -> bar-K^0n ->K^-p with the bar-K^0n pair on-mass shell. We show also how hypothesis on the dominant role of the bar-K^0n-cusp for the S-wave amplitude of low-energy K^-p scattering near threshold, used by Meissner et al., can be realized in our approach. The result agrees fully with that by Meissner et al..
We have studied in the mechanical and chemical instabilities as well as the liquid-gas phase transition in isospin asymmetric quark matter based on the NJL and the pNJL model. Areas of the mechanical instability region and the liquid-gas coexistence region are seen to be enlarged with a larger quark matter symmetry energy or in the presence of strange quarks. Our study shows that the light cluster yield ratio observed in relativistic heavy-ion collisions may not be affected much by the uncertainties of the isospin effect, while the hadron-quark phase transition in compact stars as well as their mergers is likely to be a smooth one.
We show that the contributions of three-quasiparticle interactions to normal Fermi systems at low energies and temperatures are suppressed by n_q/n compared to two-body interactions, where n_q is the density of excited or added quasiparticles and n is the ground-state density. For finite Fermi systems, three-quasiparticle contributions are suppressed by the corresponding ratio of particle numbers N_q/N. This is illustrated for polarons in strongly interacting spin-polarized Fermi gases and for valence neutrons in neutron-rich calcium isotopes.