2,215 research outputs found

    Status of Nucleon Resonances with Masses M<MN+MÏ€M<M_N+M_{\pi}

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    We discuss different interpretations of peaks observed a few years ago by Tatischeff et al. in missing mass spectra of the reaction pp−>pi+pXpp->pi^+pX, which were declared as new exited nucleon states with small masses. A study of the possible production of such states in the process γp−>pi+N∗−>pi++γγn\gamma p->pi^+N^*->pi^+ +\gamma\gamma n by analyzing the invariant mass spectrum of γγn\gamma\gamma n is proposed. It is shown that the data, obtained recently at MAMI-B, can allow to analyze this process and to get information about an existence of exited nucleon states with small masses.Comment: 4 pages, 2 figures, LaTeX with ws-p8-50x6-00.cls. Talk presented at the NSTAR2001 Workshop, Mainz, Germany, March 7-10, 200

    Inelastic semiclassical Coulomb scattering

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    We present a semiclassical S-matrix study of inelastic collinear electron-hydrogen scattering. A simple way to extract all necessary information from the deflection function alone without having to compute the stability matrix is described. This includes the determination of the relevant Maslov indices. Results of singlet and triplet cross sections for excitation and ionization are reported. The different levels of approximation -- classical, semiclassical, and uniform semiclassical -- are compared among each other and to the full quantum result.Comment: 9 figure

    Proton Decay from Excited States in Spherical Nuclei

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    Based on a single particle model which describes the time evolution of the wave function during tunneling across a one dimensional potential barrier we study the proton decay of 208^{208}Pb from excited states with non-vanishing angular momentum ℓ\ell. Several quantities of interest in this process like the decay rate λ\lambda, the period of oscillation ToscT_{osc}, the transient time ttrt_{tr}, the tunneling time ttunt_{tun} and the average value of the proton packet position rav r_{av} are computed and compared with the WKB results.Comment: 12 pages, 4 figure

    Intermanifold similarities in partial photoionization cross sections of helium

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    Using the eigenchannel R-matrix method we calculate partial photoionization cross sections from the ground state of the helium atom for incident photon energies up to the N=9 manifold. The wide energy range covered by our calculations permits a thorough investigation of general patterns in the cross sections which were first discussed by Menzel and co-workers [Phys. Rev. A {\bf 54}, 2080 (1996)]. The existence of these patterns can easily be understood in terms of propensity rules for autoionization. As the photon energy is increased the regular patterns are locally interrupted by perturber states until they fade out indicating the progressive break-down of the propensity rules and the underlying approximate quantum numbers. We demonstrate that the destructive influence of isolated perturbers can be compensated with an energy-dependent quantum defect.Comment: 10 pages, 10 figures, replacement with some typos correcte

    Adiabatic entanglement transport in Rydberg aggregates

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    We consider the interplay between excitonic and atomic motion in a regular, flexible chain of Rydberg atoms, extending our recent results on entanglement transport in Rydberg chains [W\"uster et al., Phys.Rev.Lett 105 053004 (2010)]. In such a Rydberg chain, similar to molecular aggregates, an electronic excitation is delocalised due to long range dipole-dipole interactions among the atoms. The transport of an exciton that is initially trapped by a chain dislocation is strongly coupled to nuclear dynamics, forming a localised pulse of combined excitation and displacement. This pulse transfers entanglement between dislocated atoms adiabatically along the chain. Details about the interaction and the preparation of the initial state are discussed. We also present evidence that the quantum dynamics of this complex many-body problem can be accurately described by selected quantum-classical methods, which greatly simplify investigations of excitation transport in flexible chains
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