Article

# Invariant-mass distributions for the pp → ppη reaction at Q = 10 MeV

[more]
(Impact Factor: 2.74). 01/2010; 43(2). DOI: 10.1140/epja/i2009-10900-9
Source: arXiv

ABSTRACT

Proton-proton and proton- $\eta$ invariant-mass distributions and the total cross-section for the pp $\rightarrow$ pp $\eta$ reaction have been determined near the threshold at an excess energy of Q = 10 MeV. The experiment has been conducted using the COSY-11 detector setup and the cooler synchrotron COSY. The determined invariant-mass spectra reveal significant enhancements in the region of low proton-proton relative momenta, similarly as observed previously at higher excess energies of Q = 15.5 MeV and Q = 40 MeV.

### Full-text

Available from: Michal Silarski,
• Source
##### Article: Baryon resonance production in the $\pi+d$ reaction and search for $\eta$-mesic nuclei at J-PARC
[Hide abstract]
ABSTRACT: A double-scattering reaction $\pi^+ + d\to p + p + \eta$, where an $\eta$ meson is rescattered, may provide new information on the $\eta N\to \eta N$ scattering. An idea to measure this reaction is proposed. Moreover, experimental search for $\eta$-mesic nuclei by the same $(\pi, N)$ reaction is discussed.
• Source
##### Article: Production in nucleon-nucleon collisions
[Hide abstract]
ABSTRACT: New experimental data are presented on the energy dependence of the total cross sections for the np -> d eta and quasi-two-body pp -> pp eta reactions, where the final diproton is detected at very low excitation energy. Differential cross sections of pp -> pp eta away from threshold show the influence of higher partial waves and a partial wave decomposition is attempted. Comment: Invited talk at the International Symposium on Mesic Nuclei, Krakow, 16 June 16 2010
• Source
##### Article: η-meson production in proton-proton collisions at excess energies of 40 and 72 MeV
[Hide abstract]
ABSTRACT: The production of η mesons in proton-proton collisions has been studied using the WASA detector at the CELSIUS storage ring at excess energies of Q=40 MeV and Q=72 MeV. The η was detected through its 2γ decay in a near-4π electromagnetic calorimeter, whereas the protons were measured by a combination of straw chambers and plastic scintillator planes in the forward hemisphere. About 6.9×104 and 9.3×104 events were found at Q=40 MeV and Q=72 MeV, respectively, with background contributions of less than 5%. A simple parametrization of the production cross section in terms of low partial waves was used to evaluate the acceptance corrections. Strong evidence was found for the influence of higher partial waves. The Dalitz plots show the presence of p waves in both the pp and the η{pp} systems and the angular distributions of the η in the center-of-mass frame suggest the influence of d-wave η mesons.
Physical Review C 11/2010; 82(5). DOI:10.1103/PhysRevC.82.055206 · 3.73 Impact Factor