Study of the eta meson production with the polarised proton beam

The azimuthally symmetric WASA detector and the polarised proton beam of COSY, enable investigations of energy and angular dependence of the beam analysing power in the pp --> ppeta reaction. The aim of the studies is the determination of the partial wave contributions via interference terms which are inaccessible from spin averaged observables. The partial wave decomposition is mandatory for the understanding of the reaction dynamics and for the determination of the eta-proton interaction, independently of the theoretical paradigm used.Comment: To be published in J. Phys. Conf. Ser. in the second quarter of 201

Etaprime and Eta Mesons with Connection to Anomalous Glue

We review the present understanding of etaprime and eta meson physics and these mesons as a probe of gluon dynamics in low-energy QCD. Recent highlights include the production mechanism of eta and etaprime mesons in proton-nucleon collisions from threshold to high-energy, the etaprime effective mass shift in the nuclear medium, searches for possible eta and etaprime bound states in nuclei as well as precision measurements of eta decays as a probe of light-quark masses. We discuss recent experimental data, theoretical interpretation of the different measurements and the open questions and challenges for future investigation.Comment: Review, 25 pages, 11 figures, to appear in Reviews of Modern Physic

Status and Perspectives of the Search for Eta-Mesic Nuclei

In this report the search for eta-mesic nuclei is reviewed. The brief description of the experimental studies is presented with a focus on the possible production of the eta-nucleus bound states for light nuclei like 4He and 3He.Comment: Conference Proceedings: The 11th Latin American Symposium on Nuclear Physics and Applications (XI LASNPA), 30.11-04.12.2015, Medellin, Columbi

Study of the Decoherence of Entangled Kaons by the Interaction with Thermal Photons

The KLOE-2 detector is a powerful tool to study the temporal evolution of quantum entangled pairs of kaons. The accuracy of such studies may in principle be limited by the interaction of neutral kaons with thermal photons present inside the detector. Therefore, it is crucial to estimate the probability of this effect and its influence on the interference patterns. In this paper we introduce the phenomenology of the interaction of photons with neutral kaons and present and discuss the obtained quantitative results.Comment: Proceeding from 2nd Young Researchers Workshop: Physics Challenges in the LHC Era, Frascati, May 10 and 13, 2010; 6 pages, 4 figure

Studies of systematic uncertainties of polarization estimation for experiments with WASA detector at COSY

In November 2010, the azimuthally symmetric WASA detector and the polarized proton beam of COSY, have been used to collect a high statistics sample of $\vec{p}p \rightarrow pp\eta$ reactions in order to determine the analyzing power as a function of the invariant mass spectra of the two particle subsystems. Here, we show studies of the influence of the beam and target characteristics such as location and direction on the determination of the polarization.Comment: Presented at Symposium on applied nuclear physics and innovative technologies, Krakow, 3-6.06.2013; Accepted to Acta Physica Polonica B Proceedings Supplement, Vol. 6 (2013); 12 page

Search for the manifestation of the mesic-nuclei on the dd-->3HeNpi excitation function measured with WASA-at-COSY

We search for an evidence of eta-mesic 4He with the WASA-at-COSY detector. Two dedicated experiments were performed at the Cooler Synchrotron COSY-Juelich. The experimental method is based on the measurement of the excitation functions for the two reaction channels: dd-->3Heppi- and dd-->3Henpi0, where the outgoing N-pi pairs originate from the conversion of the eta meson on a nucleon inside the He nucleus. In this contribution, the experimental method is shortly described and preliminary excitation functions from the 2010 data are presented.Comment: 8 pages, 12 figures, Presented at International Symposium on Mesic Nuclei, Krakow, Sept. 20, 201

Search for eta-mesic nuclei with WASA-at-COSY

We search for an evidence of eta-mesic He with the WASA detector. Two dedicated experiments were performed at the Cooler Synchrotron COSY-Juelich. The experimental method is based on the measurement of the excitation functions for the two reaction channels: dd->3Heppi- and dd->3Henpi0, where the outgoing N-pi pairs originate from the conversion of the eta meson on a nucleon inside the He nucleus.In this contribution, the experimental method is shortly described and the current status of the analysis is presented.Comment: 5 pages, 2 figure

Search for eta-mesic Helium with the WASA-at-COSY detector

A search for the 4He-eta bound state via exclusive measurement of the excitation function for the dd->3Heppi- reaction, was performed at the Cooler Synchrotron COSY-Juelich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 GeV/c to 2.400 GeV/c crossing the kinematic threshold for the eta production in the dd -> 4He-eta reaction at 2.336 GeV/c. The corresponding excess energy in the 4He-eta system varied from -51.4 MeV to 22 MeV. The shape of the excitation function for the dd -> 3Heppi- was examined. No signal of the 4He-eta bound state was observed in the excitation function.Comment: 4 pages, 5 figures, to appear in proceedings of MESON201

Updating spin-dependent Regge intercepts

We use new high statistics data from CLAS and COMPASS on the nucleon's spin structure function at low Bjorken x and low virtuality, Q^2 < 0.5 GeV^2, together with earlier measurements from the SLAC E-143, HERMES and GDH experiments to estimate the effective intercept(s) for spin dependent Regge theory. We find alpha_{a_1} = 0.31 \pm 0.04 for the intercept describing the high-energy behaviour of spin dependent photoabsorption together with a new estimate for the high-energy part of the Gerasimov-Drell-Hearn sum-rule, -15 \pm 2 mu b from photon-proton centre-of-mass energy greater than 2.5 GeV. Our value of alpha_[a_1} suggests QCD physics beyond a simple straight-line a_1 trajectory.Comment: 4 pages, 1 figure, to appear in Physical Review