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1.
We calculate s-wave and p-wave absorptive pion-nucleus optical potentials assuming that a pion is absorbed by a pair of nucleons. Employing a model which takes into account both a single nucleon absorption with nucleon-nucleon correlations and rescattering, we obtain simple analytic expressions for Im B0 sid Im C0 of the pion-nucleus optical potential. The off-shell effect on the s-wave pion absorption is examined and shown to be strongly modified by short range correlations. The result for the p-wave absorptive part Im C0 clearly shows the importance of the tensor correlations. The enhanced nn emission after π? absorption is shown to be related with a large p-wave πN scattering length a33 via the tensor correlations. 相似文献
2.
Two different 6-quark resonating group models of the deuteron are investigated to study the off-shell property of theN-N interaction. In the first model the quarks interact by a central one-gluon-exchange potential plus confinement potential. The meson-exchange contribution to then-p potential is simulated by a central GaussianN-N potential. In the second model the quarks interact by one-gluon-and one-pion-exchange potentials (central and noncentral) plus confinement potential. A small additional -exchange potential between neutron and proton binds the deuteron at the correct energy.Several off-shell variants of the two resonating group models are compared with each other by analyzing their elastic electron scattering cross sections. It is found that the standard renormalized version of the resonating group model yields potentials and wave functions that may be considered physical within the limitations of the model. Unitary off-shell transformations, which modify potentials and wave functions in any sizeable way, lead to a disagreement between the charge distribution predicted by the model via analysis of electron scattering and the charge distribution following from the microscopic quark distribution.Both of the 6-quark models support a soft repulsive core of the tripletn-p potential with a core height of around 900 MeV. 相似文献
3.
A. Breakstone G. Claesson H. B. Crawley G. M. Dallavalle K. Doroba D. Drijard F. Fabbri A. Firestone M. A. Faessler H. G. Fischer S. Y. Fung S. Garpman W. Geist G. Giacomelli R. Gokieli M. Gorbics C. R. Gruhn P. Hanke M. Heiden W. Herr T. J. Ketel E. E. Kluge J. W. Lamsa T. Lohse I. Lund R. Mankel W. T. Meyer G. Mornacchi T. Nakada I. Otterlund M. Panter H. Pugh A. Putzer K. Rauschnabel B. Rensch F. Rimondi M. Schmelling G. P. Siroli R. Sosnowski E. Stenlund M. Szczekowski R. Szwed O. Ullaland R. Walczak D. Wegener M. Wunsch 《Zeitschrift fur Physik C Particles and Fields》1986,30(4):507-512
The relative yields of kaons and protons compared with the yield of pions at highp T and polar angles θ away from 90° (in the range from 10° to 45°) are presented forpp, dd, and αα interactions at a centre-of-mass energy \(\sqrt {s_{NN} } = 31\) GeV per nucleon-nucleon collision. The measured particle ratios depend on the atomic mass numberA of the beam particles and on θ. TheA dependence of the ratios becomes stronger for largerp T and is more pronounced at smaller polar angles. 相似文献
4.
W. Bell K. Braune G. Claesson D. Drijard M. A. Faessler H. G. Fischer H. Frehse R. W. Frey S. Garpman W. Geist C. Gruhn P. Hanke M. Heiden W. Herr P. G. Innocenti T. J. Ketel E. E. Kluge I. Lund G. Mornacchi T. Nakada I. Otterlund M. Panter B. Povh A. Putzer E. Stenlund T. J. M. Symons R. Szwed O. Ullaland 《Zeitschrift fur Physik C Particles and Fields》1986,30(4):513-520
Properties of secondaries associated with a high-p T charged trigger particle (3<p T <5 GeV/c) were studied for αp and αα interactions at c.m. energies \(\sqrt s = 88\) GeV and 125 GeV, respectively. Thep T distributions of secondaries in the away-jet and trigger-jet regions were compared with those for high-p T pp interactions. No statistically significant differences were seen, except at lowp T . Momentum and angular distributions of spectator and leading protons were studied as a function of charge and rapidity of the trigger hadron. The observed correlations between trigger charge and number of spectator protons provide evidence of valence quark contributions to the trigger jet. 相似文献
5.
A. Faessler M. Rashdan M. Ismail N. Ohtsuka W. Wadia 《Zeitschrift für Physik A Hadrons and Nuclei》1989,333(2):153-162
The effect of nuclear and Coulomb interactions on the shapes of two colliding208Pb nuclei at finite temperature is investigated. The complex potential energy density derived by Faessler and collaborators and the kinetic energy density and entropy density for two Fermi spheres at finite temperature are used to calculate the free energy of the208Pb +208Pb system in the energy density formalism. Shell corrections are added to the free energy in the framework of the Strutinsky method. The total free energy is minimized with respect to the quadrupole deformation and the diffuseness to determine the density distribution of208Pb nucleus at certain distanceR and temperatureT assuming the deformed Woods-Saxon shape for each nucleus. It is found that the nucleus acquires larger deformation and diffuseness as the temperature increases. The interaction potential between two208Pb nuclei is calculated from the minimized free energy. The total (nuclear + Coulomb) potential is found to decrease with increasing temperature, whereas the real part of the nuclear potential becomes more repulsive as the temperature increases. 相似文献
6.
Amand Faessler S. Krewald A. Plastino J. Speth 《Zeitschrift für Physik A Hadrons and Nuclei》1976,276(2):91-97
The effect of random phase ground state correlations on charge densities and elastic electron scattering cross sections is studied for208Pb and40Ca. Modifications of the charge densities relative to densities obtained by Hartree-Fock calculations with a density dependent force are studied using different RPA wave functions. The differences with respect to the HF charge distributions are discussed. 相似文献
7.
Using the statistical model, an estimate is obtained for the critical angular momentum when the rotational band ofγ-rays ends up in reactions with heavy ions. A model of classical non-quantized rotation is proposed for angular momenta exceeding the critical value. Estimates for the intensity ofγ-radiation and the descend time along the yrast-line proceeding the quantal rotation are given. 相似文献
8.
R. Bertini O. Bing P. Birien K. Braune W. Brückner H. Catz A. Chaumeaux M. A. Faessler R. -W. Frey D. Garreta T. J. Ketel K. Kilian B. Mayer J. Niewisch B. Pietrzyk B. Povh H. G. Ritter M. Uhrmacher Heidelberg -Saclay-Strasbourg Collaboration 《Nuclear Physics A》1981,360(2):315-330
Cross sections for the production of hypernuclei were measured in the reaction A(K−, π−) ΛA. on light and heavy nuclear targets, using a separated K− beam at the CERN Proton Synchrotron. The pions were detected in the forward direction. The results are compared with cross sections calculated under the assumption that the reaction took place on a single neutron. The good agreement between the measured and the calculated cross sections justifies the use of the (K−, π−) reaction in order to obtain spectroscopic information on hypernuclei. 相似文献
9.
Yubing Dong Amand Faessler Thomas Gutsche Valery E. Lyubovitskij 《Few-Body Systems》2013,54(7-10):1011-1014
The new resonances X(3872) and Λ c (2940) are considered as weakly bound states of other hadrons in a molecule scenario using phenomenological Lagrangians. 相似文献
10.
RHIC能量多粒子产生的双源统计模型分析 总被引:3,自引:0,他引:3
用双源统计模型分析研究了SNN=130 GeV Au+Au反应中的多粒子产生并与单源统计模型的结果进行了比较.研究表明,该反应有一个高温且大体积的内源.这个源的温度比SPS能量的内源至少高15MeV,体积至少大2倍,文中给出了分析 相似文献