Daniel Gazda

Chirally motivated K− nuclear potentials

Abstract In-medium subthreshold K ¯ N scattering amplitudes calculated within a chirally motivated meson–baryon coupled-channel model are used self consistently to confront K − atom data across the periodic table. Substantially deeper K − nuclear potentials are obtained compared to the shallow potentials derived in some approaches from threshold K ¯ N amplitudes, with Re V K − chiral = − ( 85 ± 5 ) MeV at nuclear matter density. When K ¯ N N contributions are incorporated phenomenologically, a very deep K − nuclear potential results, Re V K − chiral + phen . = − ( 180 ± 5 ) MeV , in agreement with density dependent potentials obtained in purely phenomenological fits to the data. Self consistent dynamical calculations of K − –nuclear quasibound states generated by V K − chiral are reported and discussed.

K^- nuclear potentials from in-medium chirally motivated models

A self consistent scheme for constructing K^- nuclear optical potentials from subthreshold in-medium Kbar-N s-wave scattering amplitudes is presented and applied to analysis of kaonic atoms data and to calculations of K^- quasibound nuclear states. The amplitudes are taken from a chirally motivated meson-baryon coupled-channel model, both at the Tomozawa-Weinberg leading order and at the next to leading order. Typical kaonic atoms potentials are characterized by a real part -Re V(K^-;chiral)=(85+/-5) MeV at nuclear matter density, in contrast to half this depth obtained in some derivations based on in-medium Kbar-N threshold amplitudes. The moderate agreement with data is much improved by adding complex rho- and rho^2-dependent phenomenological terms, found to be dominated by rho^2 contributions that could represent Kbar-NN -> YN absorption and dispersion, outside the scope of meson-baryon chiral models. Depths of the real potentials are then near 180 MeV. The effects of p-wave interactions are studied and found secondary to those of the dominant s-wave contributions. The in-medium dynamics of the coupled-channel model is discussed and systematic studies of K^- quasibound nuclear states are presented.

Calculations of K− nuclear quasi-bound states based on chiral meson–baryon amplitudes

In-medium K¯N scattering amplitudes developed within a new chirally motivated coupled-channel model due to Cieplý and Smejkal that fits the recent SIDDHARTA kaonic hydrogen 1s level shift and width are used to construct K− nuclear potentials for calculations of K− nuclear quasi-bound states. The strong energy and density dependence of scattering amplitudes at and near threshold leads to K− potential depths −ReVK≈80–120 MeV. Self-consistent calculations of all K− nuclear quasi-bound states, including excited states, are reported. Model dependence, polarization effects, the role of p-wave interactions, and two-nucleon K−NN→YN absorption modes are discussed. The K− absorption widths ΓK are comparable or even larger than the corresponding binding energies BK for all K− nuclear quasi-bound states, exceeding considerably the level spacing. This discourages search for K− nuclear quasi-bound states in any but the lightest nuclear systems.

Multi-K nuclei and kaon condensation

We extend previous relativistic mean-field (RMF) calculations of multi-K nuclei, using vector boson fields with SU(3) PPV coupling constants and scalar boson fields constrained phenomenologically. For a given core nucleus, the resulting K separation energy B{sub K}, as well as the associated nuclear and K-meson densities, saturate with the number {kappa} of K mesons for {kappa}>{kappa}{sub sat}{approx}10. Saturation appears robust against a wide range of variations, including the RMF nuclear model used and the type of boson fields mediating the strong interactions. Because B{sub K} generally does not exceed 200 MeV, it is argued that multi-K nuclei do not compete with multihyperonic nuclei in providing the ground state of strange hadronic configurations and that kaon condensation is unlikely to occur in strong-interaction self-bound strange hadronic matter. Last, we explore possibly self-bound strange systems made of neutrons and K{sup 0} mesons, or protons and K{sup -} mesons, and study their properties.

Ab Initio Description of p-Shell Hypernuclei

We present the first ab initio calculations for p-shell single-Λ hypernuclei. For the solution of the many-baryon problem, we develop two variants of the no-core shell model with explicit Λ and Σ(+),Σ(0),Σ(-) hyperons including Λ-Σ conversion, optionally supplemented by a similarity renormalization group transformation to accelerate model-space convergence. In addition to state-of-the-art chiral two- and three-nucleon interactions, we use leading-order chiral hyperon-nucleon interactions and a recent meson-exchange hyperon-nucleon interaction. We validate the approach for s-shell hypernuclei and apply it to p-shell hypernuclei, in particular to (Λ)(7)Li, (Λ)(9)Be, and (Λ)(13)C. We show that the chiral hyperon-nucleon interactions provide ground-state and excitation energies that generally agree with experiment within the cutoff dependence. At the same time we demonstrate that hypernuclear spectroscopy provides tight constraints on the hyperon-nucleon interactions.

Multi-

Relativistic mean field calculations of multi-

\bar{K}

\bar{K}

hypernuclei

hypernuclei are performed by adding

Charge symmetry breaking in the A = 4 hypernuclei

K^-

Ab initio nuclear response functions for dark matter searches

mesons to particle-stable configurations of nucleons,