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تسجيل مستخدم جديدHypercentral Constituent Quark Model with a Meson Cloud
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D. Y. Chen
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The results for the elastic nucleon form factors and the electromagnetic transition amplitudes to the Delta(1232) resonance, obtained with the Hypercentral Constituent Quark Model with the inclusion of a meson cloud correction are briefly presented. The pion cloud effects are explicitly discussed.
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We report on ongoing work to determine the pion-cloud contribution to the electromagnetic $NrightarrowDelta$ transition form factors. The starting point is an $SU(6)$ spin-flavor symmetric constituent-quark model with instantaneous confinement that i
s augmented by dynamical pions which couple directly to the quarks. This system is treated in a relativistically invariant way within the framework of point-form quantum mechanics using a multichannel formulation. The first step is to determine the electromagnetic form factors of the bare particles that consist only of three quarks. These form factors are basic ingredients for calculating the pion-cloud contributions. Already without the pion cloud, electromagnetic nucleon and $Nrightarrow Delta$ transition form factors compare reasonably well with the data. By inclusion of the pion-cloud contribution coming from the $pi$-$N$ intermediate state the reproduction of the data is further improved.
${bf Background}$ Knowledge of nucleon structure is today ever more of a precision science, with heightened theoretical and experimental activity expected in coming years. At the same time, a persistent gap lingers between theoretical approaches grou
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An improved quark mass density- dependent model with the non-linear scalar sigma field and the $omega$-meson field is presented. We show that the present model can describe saturation properties, the equation of state, the compressibility and the eff
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There exists experimental evidence that a dibaryon resonance d with quantum numbers J^P=0^-,T=0 and mass 2065 MeV could be the origin of the narrow peak in the (pi^+ ,pi^- ) double charge exchange cross--sections on nuclei. We investigate the six--qu
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