Publications (7)2.19 Total impact
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Article: Cross section of the $pp\to K^+\Sigma^+n$ reaction close to threshold
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ABSTRACT: We have measured inclusive data on $K^+$-meson production in $pp$ collisions at COSY J\"ulich close to the hyperon production threshold and determined the hyperon-nucleon invariant mass spectra. The spectra were decomposed into three parts: $\Lambda p$, $\Sigma^0p$ and $\Sigma^+n$. The cross section for the $\Sigma^+n$ channel was found to be much smaller than a previous measurement in that excess energy region. The data together with previous results at higher energies are compatible with a phase space dependence. Comment: accepted by Phys. lett. B some typos corrected07/2010; -
Article: Influence of N*-resonances on hyperon production in the channel pp->K+ Lambda p at 2.95, 3.20 and 3.30 GeV/c beam momentum
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ABSTRACT: Hyperon production in the threshold region was studied in the reaction pp -> K+Lp using the time-of-flight spectrometer COSY-TOF. Exclusive data, covering the full phase-space, were taken at the three different beam momenta of p_beam=2.95, 3.20 and 3.30 GeV/c, corresponding to excess energies of epsilon=204, 285 and 316 MeV, respectively. Total cross-sections were deduced for the three beam momenta to be 23.9+/-0.8 +/-2.0 ub, 28.4+/-1.3 +/-2.2 ub and 35.0+/-1.3 +/-3.0 ub. Differential observables including Dalitz plots were obtained. The analysis of the Dalitz plots reveals a strong influence of the N(1650)-resonance at p_beam=2.95 GeV/c, whereas for the higher momenta an increasing relative contribution of the N(1710)- and/or of the N(1720)-resonance was observed. In addition, the pL-final-state interaction turned out to have a significant influence on the Dalitz plot distribution. Comment: accepted for publication at Physics Letters B; some minor text changes were done; also the scale of the ordinates of figure 9 has been changed;03/2010; -
Article: High resolution study of the Lambda p final state interaction in the reaction p + p -> K+ + (Lambda p)
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ABSTRACT: The reaction pp -> K+ + (Lambda p) was measured at Tp=1.953 GeV and Theta = 0 deg with a high missing mass resolution in order to study the Lambda p final state interaction. The large final state enhancement near the Lambda p threshold can be described using the standard Jost-function approach. The singlet and triplet scattering lengths and effective ranges are deduced by fitting simultaneously the Lambda p invariant mass spectrum and the total cross section data of the free Lambda p scattering. Comment: submitted to Physics Letters B, 10 pages, 3 figures03/2010; -
Article: Cross sections of the $pp\to K^+\Sigma^+n$ reaction close to threshold
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ABSTRACT: The paper is obsolete11/2009; -
Article: Improved study of a possible Theta+ production in the pp -> p K0 sigma+ reaction with the COSY-TOF spectrometer
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ABSTRACT: The pp -> p K0 Sigma+ reaction was investigated with the TOF spectrometer at COSY at 3.059 GeV/c incident beam momentum. The main objective was to clarify whether or not a narrow exotic S = +1 resnance, the Theta+ pentaquark, is populated at 1.53 GeV/c2 in the K0 p subsystem with a data sample of much higher statistical significance compared to the previously reported data in this channel. An analysis of these data does not confirm the existence of the Theta+ pentaquark. This is expressed as an upper limit for the cross section sigma (pp -> p K0 Sigma+) < 0.15 microbarn at the 95 percent confidence level.01/2007; -
Article: Measurement of the η production in proton-proton collisions with the COSY time-of-flight spectrometer
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ABSTRACT: The reaction pp → ppη was measured at excess energies of 15 and 41 MeV at an external target of the Jülich Cooler Synchrotron COSY with the time-of-flight spectrometer. About 25000 events were measured for the excess energy of 15 MeV and about 8000 for 41 MeV. Both protons of the process ppη were detected with an acceptance of nearly 100% and the η was reconstructed by the missing-mass technique. For both excess energies the angular distributions are found to be nearly isotropic. In the invariant-mass distributions strong deviations from the pure phase space distributions are seen.European Physical Journal A 12/2002; 16(1):127-137. · 2.19 Impact Factor -
Article: High resolution study of the Λp final state interaction in the reaction p+p→K++(Λp)
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ABSTRACT: The reaction pp→K++(Λp) was measured at Tp=1.953 GeV and Θ=0° with a high missing mass resolution in order to study the Λp final state interaction. The large final state enhancement near the Λp threshold can be described using the standard Jost-function approach. The singlet and triplet scattering lengths and effective ranges are deduced by fitting simultaneously the Λp invariant mass spectrum and the total cross section data of the free Λp scattering.Physics Letters B.
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Institutions
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2002–2010
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Eberhard-Karls-Universität Tübingen
- Institute of Physical and Theoretical Chemistry
Tübingen, Baden-Wuerttemberg, Germany
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