In-medium Eta-Nucleon interactions and Eta nuclear bound states

The in-medium Eta-N interaction near and below threshold is constructed from a free-space chirally-inspired meson-baryon coupled-channel model that captures the physics of the N(1535) baryon resonance. Nucleon Pauli blocking and hadron self-energies are accounted for. The resulting energy dependent in-medium interaction is used in self-consistent dynamical calculations of Eta nuclear bound states. Narrow states of width about or less than 2 MeV are found across the periodic table, beginning with A=10, for this in-medium coupled-channel interaction model. The binding energy of the 1s-Eta state increases with A, reaching a value of B(1s-Eta) about 15 MeV. The implications of our self-consistency procedure are discussed with respect to procedures used in other works.Comment: 21 pages, 1 table, 8 figures, matches published NPA version plus a new review [34] cite

Onset of η\eta-nuclear binding in a pionless EFT approach

$\eta NNN$ and $\eta NNNN$ bound states are explored in stochastic variational method (SVM) calculations within a pionless effective field theory (EFT) approach at leading order. The theoretical input consists of regulated $NN$ and $NNN$ contact terms, and a regulated energy dependent $\eta N$ contact term derived from coupled-channel models of the $N^{\ast}(1535)$ nucleon resonance plus a regulated $\eta NN$ contact term. A self consistency procedure is applied to deal with the energy dependence of the $\eta N$ subthreshold input, resulting in a weak dependence of the calculated $\eta$-nuclear binding energies on the EFT regulator. It is found, in terms of the $\eta N$ scattering length $a_{\eta N}$, that the onset of binding $\eta\,^3$He requires a minimal value of Re$\,a_{\eta N}$ close to 1 fm, yielding then a few MeV $\eta$ binding in $\eta\,^4$He. The onset of binding $\eta\,^4$He requires a lower value of Re$\,a_{\eta N}$, but exceeding 0.7 fm.Comment: v4 consists of the published Physics Letters B version [31] plus Erratum ([30], Appendix A here); main results and conclusions remain intac

In-medium nuclear interactions of low-energy hadrons

Experimental and theoretical developments of the last decade in the study of exotic atoms and some related low-energy reactions are reviewed, in order to provide information on the in-medium hadron-nucleon t matrix over a wide range of densities up to central nuclear densities. In particular, we review pionic deeply bound atomic states and related evidence for partial restoration of chiral symmetry in dense nuclear matter. The case for relatively narrow deeply bound atomic states for antikaons and antiprotons is made, based on the physics of strong nuclear absorption. Recent experimental suggestions for signals of antikaon-nuclear deeply bound states are reviewed, and dynamical models for calculating binding energies, widths and densities of antikaon nuclear states are discussed. Specific features of low-energy in-medium interactions of kaons, antiprotons and of Sigma hyperons are discussed, and suggestions to study experimentally Cascade atoms are reviewed.Comment: 86 pages, 44 figures, slight revisions, references added, Physics Reports (in press

Photometric validation of a model independent procedure to extract galaxy clusters

By means of CCD photometry in three bands (Gunn g, r, i) we investigate the existence of 12 candidate clusters extracted via a model independent peak finding algorithm (\cite{memsait}) from DPOSS data. The derived color-magnitude diagrams allow us to confirm the physical nature of 9 of the cluster candidates, and to estimate their photometric redshifts. Of the other candidates, one is a fortuitous detection of a true cluster at z~0.4, one is a false detection and the last is undecidable on the basis of the available data. The accuracy of the photometric redshifts is tested on an additional sample of 8 clusters with known spectroscopic redshifts. Photometric redshifts turn out to be accurate within z~0.01 (interquartile range).Comment: A&A in pres

Multi-Kˉ\bar{K} nuclei and kaon condensation

We extend previous relativistic mean-field (RMF) calculations of multi-$\bar K$ nuclei, using vector boson fields with SU(3) PPV coupling constants and scalar boson fields constrained phenomenologically. For a given core nucleus, the resulting $\bar K$ separation energy $B_{\bar K}$, as well as the associated nuclear and $\bar K$-meson densities, saturate with the number $\kappa$ of $\bar K$ mesons for $\kappa > \kappa_{\rm sat} \sim 10$. 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 $B_{\bar K}$ generally does not exceed 200 MeV, it is argued that multi-$\bar K$ 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 ${\bar K}^0$ mesons, or protons and $K^-$ mesons, and study their properties.Comment: 21 pages, 8 figures, revised text and reference