共查询到20条相似文献,搜索用时 15 毫秒
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M. J. Zieliński P. Moskal A. Kupść 《The European Physical Journal A - Hadrons and Nuclei》2011,47(8):1-6
Isospin violating hadronic decays of the $ \eta$ and $ \eta{^\prime}$ mesons into 3 $ \pi$ mesons are driven by a term in the QCD Lagrangian proportional to the mass difference of the d and u quarks. The source giving large yield of the mesons for such decay studies are pp interactions close to the respective kinematical thresholds. The most important physics background for $ \eta$ , $ \eta{^\prime}$ $ \rightarrow$ $ \pi$ $ \pi$ $ \pi$ is coming from direct three-pion production reactions. In case of the $ \eta$ meson the background for the decays is relatively low ( $ \approx$ 10% . The purpose of this article is to provide an estimate of the direct pion production background for the $ \eta{^\prime}$ $ \rightarrow$ 3 $ \pi$ decays. Using the inclusive data from the COSY-11 experiment we have extracted the differential cross-section for the pp $ \rightarrow$ pp -multipion production reactions with the invariant mass of the pions equal to the $ \eta{^\prime}$ meson mass and estimated an upper limit for the signal to background ratio for studies of the $ \eta{^\prime}$ $ \rightarrow$ $ \pi^{+}_{}$ $ \pi^{-}_{}$ $ \pi^{0}_{}$ decay. 相似文献
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M. Abdel-Bary S. Abdel-Samad K. -Th. Brinkmann H. Clement J. Dietrich E. Doroshkevich S. Dshemuchadse K. Ehrhardt A. Erhardt W. Eyrich A. Filippi H. Freiesleben M. Fritsch W. Gast A. Gillitzer J. Gottwald H. J?ger B. Jakob R. J?kel L. Karsch K. Kilian H. Koch M. Krapp J. Kre? E. Kuhlmann A. Lehmann S. Marcello S. Mauro P. Michel K. Móller H. P. Morsch L. Naumann N. Paul C. Pizzolotto Ch. Plettner S. Reimann M. Richter J. Ritman E. Roderburg A. Schamlott P. Sch?nmeier W. Schroeder M. Schulte-Wissermann T. Sefzick M. Steinke G. Y. Sun A. Teufel W. Ullrich G. J. Wagner M. Wagner R. Wenzel A. Wilms P. Wintz P. Wüstner P. Zupranski 《The European Physical Journal A - Hadrons and Nuclei》2010,44(1):7-22
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P. Moskal R. Czy?ykiewicz E. Czerwiński D. Gil D. Grzonka L. Jarczyk B. Kamys A. Khoukaz J. Klaja P. Klaja W. Krzemień W. Oelert J. Ritman T. Sefzick M. Siemaszko M. Silarski J. Smyrski A. T?schner M. Wolke P. Wüstner J. Zdebik M. J. Zieliński W. Zipper 《The European Physical Journal A - Hadrons and Nuclei》2010,43(2):131-136
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. 相似文献
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E. Doroshkevich M. Bashkanov W. Brodowski R. Bilger H. Calén H. Clement C. Ekström K. Fransson J. Greiff S. Häggström B. Höistad J. Johanson A. Johansson T. Johansson K. Kilian S. Kullander A. Kupsc P. Marciniewski R. Meier B. Morosov W. Oelert J. Pätzold R. J. M. Y. Ruber W. Scobel J. Stepaniak A. Sukhanov A. Turowiecki G. J. Wagner Z. Wilhelmi J. Zabierowski J. Zlomanczuk 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):171-176
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P. Winter H.-H. Adam A. Budzanowski R. Czyzykiewicz D. Grzonka M. Janusz L. Jarczyk B. Kamys A. Khoukaz K. Kilian P. Kowina T. Lister P. Moskal W. Oelert C. Piskor-Ignatowicz T. Rozek R. Santo G. Schepers T. Sefzick M. Siemaszko J. Smyrski S. Steltenkamp A. Strzalkowski A. Täschner M. Wolke P. Wüstner W. Zipper 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):355-357
At the internal facility COSY-11 a first measurement of the reaction
near the production threshold has been performed. Results for the analysing power will be presented and a comparison with one-meson exchange models will be discussed.Received: 30 September 2002, Published online: 22 October 2003PACS:
12.40.Vv Vector-meson dominance - 13.60.Le Meson production - 13.88. + e Polarization in interactions and scattering - 24.70. + s Polarization phenomena in reactions 相似文献
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B. L. Druzhinin A. E. Kudryavtsev V. E. Tarasov 《Zeitschrift für Physik A Hadrons and Nuclei》1997,359(2):205-209
The reaction pp → ppη near the kinematical threshold is considered in the framework of the model, which includes the pp final states interaction (FSI). The Coulomb and strong effects of the pp FSI are calculated correctly in the model “Coulomb + Yamaguchi potential”. The pp FSI is shown to provide the main contribution to the energy dependence of the total cross section of the pp → ppη reaction close to threshold. The energy behavior of the total cross section is predicted in agreement with the data in the excess energy region < 15MeV. The predictions for different spectra are also performed. 相似文献
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The resonance Raman (RR) spectra of nickel octaethyl porphyrin, Ni(OEP), in CH2Cl2 (solvent) at different excitations such as 514.5, 488.0, 441.6 and 406.7 nm are recorded and analysed. The results of the
theory of distortion-induced RR intensity is applied to the observed spectra to determine the excited electronic state symmetry
of porphyrin in Ni(OEP). It is concluded that the porphyrin molecule (D4h structure) attains a non-polar distorted structure of D2 symmetry rather than S4 symmetry in CH2Cl2 solution. 相似文献
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D. A. Sharov V. L. Korotkikh D. E. Lanskoy 《The European Physical Journal A - Hadrons and Nuclei》2011,47(9):1-12
A phenomenological model for the $ \overline{{K}}$ N $ \rightarrow$ K $ \Xi$ reaction is suggested. The model includes s and u channel exchanges by $ \Lambda$ , $ \Sigma$ , $ \Sigma$ (1385) , and $ \Lambda$ (1520) and s channel exchanges by above-threshold hyperonic resonances. The explicit expression for the propagator for a particle with spin 7/2 is presented. High-mass and high-spin resonances play a significant role in the process. We deal with the whole set of existing experimental data on the cross-sections and polarizations in the energy range from the threshold to 2.8GeV in the center-of-mass system and reach a good agreement with experiments. Applications of the model to other elementary reactions of $ \Xi$ production and to $ \Xi$ hypernuclear spectroscopy are briefly discussed. 相似文献
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Kinematically complete measurements of the
reaction were performed for beam energies in the range 292-298 MeV. We detected both protons in coincidence by using the large-acceptance COSY-TOF spectrometer and an external proton beam at COSY-JÃ&frac;lich; thus, we measured total and differential cross-sections and energy distributions. A strong enhancement was observed in the Dalitz plots due to the final-state interaction between the two outgoing protons; the data are well reproduced by Monte Carlo simulations using a standard scattering length of a0=-7.83 fm and effective range of r0=2.8 fm. Our measured total cross-sections are roughly
larger than those of recent internal-target experiments at IUCF and CELSIUS. This discrepancy may be due to the final-state interaction pushing some events into the very small-angle region which is almost inaccessible to an internal-target experiment. In the angular distributions we found only very slight deviations from isotropy. The analysis of our momentum distributions yielded a small fraction of
for Ps or Pp wave contributions.PACS:
13.75.Cs Nucleon-nucleon interactions (including antinucleons, deuterons, etc.) - 25.10.+s Nuclear reactions involving few-nucleon systems - 25.40.Ep Inelastic proton scattering - 29.20.Dh Storage rings 相似文献
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S. Barsov I. Lehmann R. Schleichert C. Wilkin M. Büscher S. Dymov Ye Golubeva M. Hartmann V. Hejny A. Kacharava I. Keshelashvili A. Khoukaz V. Komarov L. Kondratyuk N. Lang G. Macharashvili T. Mersmann S. Merzliakov A. Mussgiller M. Nioradze A. Petrus H. Ströher Y. Uzikov B. Zalikhanov 《The European Physical Journal A - Hadrons and Nuclei》2004,21(3):521-527
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Stefano Piano 《Hyperfine Interactions》2012,210(1-3):97-101
A study of the $K^-_{\rm stop}A\rightarrow \Sigma^\pm\pi^\mp A^{\prime}$ reaction in some p-shell nuclei, i.e., 6,7Li, 9Be, 13C and 16O, performed by the FINUDA experiment, is reported. 相似文献