Search for the eta-mesic helium at COSY

We review status and perspectives of the search of the eta-mesic helium at the cooler synchrotron COSY.Comment: Invited talk at the Excited QCD 09 Workshop, 8-14 February 2009, Zakopane, Poland, 6 page

Combined analysis of the K+K−K^{+}K^{-} interaction using near threshold pp→ppK+K−pp \to ppK^+K^- data

The $K^{+}K^{-}$ final state interaction was investigated based on both the $K^{+}K^{-}$ invariant mass distributions measured at excess energies of Q = 10 and 28 MeV and the near threshold excitation function for the $pp \to ppK^{+}K^{-}$ reaction. The $K^+K^-$ final state enhancement factor was parametrized using the effective range expansion. The effective range of the $K^+K^-$ interaction was estimated to be: $\mathrm{Re}(b_{K^{+}K^{-}}) = -0.1 \pm 0.4_{stat} \pm 0.3_{sys} \mathrm{fm}$ and $\mathrm{Im}(b_{K^{+}K^{-}}) = 1.2^{+0.1_{stat}+0.2_{sys}}_{-0.2_{stat}-0.0_{sys}} \mathrm{fm}$, and the determined real and imaginary parts of the $K^+K^-$ scattering length amount to: $|\mathrm{Re}(a_{K^{+}K^{-}})| = 8.0^{+6.0_{stat}}_{-4.0_{stat}} \mathrm{fm}$ and $\mathrm{Im}(a_{K^{+}K^{-}}) = 0.0^{+20.0_{stat}}_{-5.0_{stat}} \mathrm{fm}$.Comment: 5 pages, 3 figures, article accepted for publication in Phys. Rev.

Search for the eta-mesic nuclei by means of COSY-11, WASA-at-COSY and COSY-TOF detector systems

We review status and perspectives of the search for the light eta-mesic nuclei using COSY-11, WASA-at-COSY and COSY-TOF detector systems.Comment: Invited talk at the International Symposium on Mesic Nuclei, Krakow, 16 June 201

Test of charge conjugation invariance in the decay of the eta meson into pi(+)pi(-)pi(0)

In this work we present the preliminary results of the analysis of the pp->pp eta(->pp pi(+)pi(-)pi(0) reaction aiming to test the charge conjugation symmetry C in strong interactions. Based on approximately $10^5$ identified eta->pi(+)pi(-)pi(0) decay events we have extracted asymmetry parameters sensitive to C symmetry violation for different isospin values of the final state and we have established that all are consistent with zero within the obtained accuracy.Comment: MESON2012 - 12th International Workshop on Meson Production, Properties and Interactio

Experimental proton-proton correlation function derived for the pp -> ppeta reaction

Based on the high statistics data from the pp -> ppX reaction measured by the COSY-11 collaboration [1] we have derived a two-proton correlation function for the production of the ppeta and pp+pions systems. The measured correlation function normalized to the value simulated for a point-like source was compared with a theoretical prediction in order to estimate the size of the reaction volume.Comment: Talk given at the Symposium on Meson Physics at COSY-11 and WASA-at-COSY Krakow, Poland, 17-22 June 200

Luminosity determination for the quasi-free nuclear reactions

A method for the calculation of the luminosity for the proton-nucleus collisions based on the quasi-free proton-proton scattering is presented. As an example of application the integrated luminosity for the scattering of protons off the deuteron target is determined for the experiment of the quasi-free pn --> pneta reaction performed by means of the COSY-11 facility.Comment: 7 pages, 5 figures, Presented at Symposium on Meson Physics at COSY-11 and WASA-at-COSY, Cracow, Poland, 17-22 Jun 200

Genuine Multipartite Entanglement in the 33-Photon Decay of Positronium

The electron-positron annihilation into two photons is a standard technology in medicine to observe e.g. metabolic processes in human bodies. A new tomograph will provide the possibility to observe not only direct $e^+ e^-$ annihilations but also the $3$ photons from the decay of ortho-positronium atoms formed in the body. We show in this contribution that the three-photon state with respect to polarisation degrees of freedom depends on the angles between the photons and exhibits various specific entanglement features. In particular genuine multipartite entanglement, a type of entanglement involving all degrees of freedoms, is subsistent if the positronium was in a definite spin eigenstate. Remarkably, when all spin eigenstates are mixed equally, entanglement --and even stronger genuine multipartite entanglement-- survives. Due to a "\textit{symmetrization}" process, however, $Dicke$-type of entanglement remains whereas $GHZ$-type of entanglement vanishes. The survival of particular entanglement properties in the mixing scenario may make it possible to extract quantum information in form of distinct entanglement features, e.g., from metabolic processes in human bodies.Comment: 9 pages, 5 figure

Search for the 4He-eta bound state in dd->(4He-eta)_{bound}->3He n pi0 and dd->(4He-eta)_{bound}->3He p pi- reactions with the WASA-at-COSY facility

In November 2010, the search for the 4He-{\eta} bound state was per formed with high statistics and high acceptance with the WASA-at-COSY facility using a ramped beam technique. The signature of eta - mesic nuclei is searched for in the measured excitation functions for the two reaction channels: dd ->3He n pi0 and dd ->3He p pi- near the eta production threshold. This report includes the description of the experimental method and the status of the data analysis.Comment: 4 page

Close to threshold eta' meson production in proton-proton collisions at COSY-11

Intensive quest for the eta and eta' bound states is currently ongoing at both theoretical and experimental levels e.g. at COSY, ELSA, GSI, JINR, JPARC, LPI, and MAMI. These studies were already supported by data provided by the COSY-11 collaboration including determination of the total width of the eta' meson. In addition, the first rough estimation of the eta'-N interaction from the excitation function of the cross section for the pp-->pp eta' reaction was also performed. Recent precise measurement in this field from the COSY-11 experiment allows to summarize results on the eta' meson production cross section in proton-proton collisions at COSY-11.Comment: 4 pages, 1 figure, presented at 13th International Workshop on Meson Production, Properties and Interaction, Cracow, Poland, 29th May - 3rd June 201